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for MAJOR PROJECT
Under the guidance of Mrs.Pooja Kaushik
CHAPTER 1 1. Introduction
A robotic arm is a type of mechanical arm, usually programmable, with similar functions to a human arm; the arm may be the sum total of the mechanism or may be part of a more complex robot. The links of such a manipulator are connected by joints allowing either rotational motion (such as in an articulated robot) or translational (linear) displacement.[1][2] The links of the manipulator can be considered to form a kinematic chain. The terminus of the kinematic chain of the manipulator is called the end effectors and it is analogous to the human hand. Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. At a very basic level hydraulics is the liquid version of pneumatics. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through some part of science and most of engineering modules, and cover concepts such as pipe flow,dam design, fluidics and fluid controlcircuitry, pumps, turbines, hydropower, computational fluid dynamics, flow measurement, river channel behavior and erosion. Free surface hydraulics is the branch of hydraulics dealing with free surface flow, such as occurring in rivers, canals, lakes, estuariesand seas. Its sub-field open channel flow studies the flow in open channels. The word "hydraulics" originates from the Greek word ὑδραυλικός (hydraulikos) which in turn originates from ὕδωρ (hydor, Greek for water) and αὐλός (aulos, meaning pipe). Hydraulics is used in many applications we see or use every day. The brakes in an automobile or the lift on the bucket of a tractor are two very common applications. We can experiment with simple hydraulics using plastic syringes for cylinders and small plastic tubing for the hydraulic hose. One definition I read for hydraulics was, "the movement of pressurized liquids through confined spaces" Like working with gears, pulleys, or levers; a mechanical advantage can be realized by using different size cylinders on the end of the hydraulic connections. with the amount of force the advantage is realized. By trading distance moved
1.1 Objectives:
• The main objective of this project is to build a unique kind of robotic algorithm to achieve a New kind of approachability in the field of robotics. • The robotic arm is one of those types of different view for automation in machines. • These robots are designed to clean or pull up and down any obstructions.
1.2 Scope:
basic robotics we design machines to do the specified tasks and in the advanced version of it
robots are designed to be adaptive, that is, respond according to the changing environment and even autonomous, that is, capable to make decisions on their own. While designing a robot the most important thing to be taken in consideration is, obviously, the function to be performed. Here comes into play the discussion about the scope of the robot and robotics. Robots have basic levels of complexity and each level has its scope for performing the requisite function. The levels of complexity of robots is defined by the members used in its limbs, number of limbs, number of actuators and sensors used and for advanced robots the type and number of microprocessors and microcontrollers used. Each increasing component adds to the scope of functionality of a robot. With every joint added, the degrees of freedom in which a robot can work increases and with the quality of the microprocessors and microcontrollers the accuracy and effectiveness with which a robot can work is enhanced.
Inputs: 1. Hydraulic cylinders (Syringe with clips and mounts) 2. Hydraulic Lines (Vinyl Tubing) 3. Perpendicular wooden blocks and Dowels 4. Chip board
5. Screws 6. 10 square nuts 7. 10 washers 8. Connector strips 9. Galvanised coloured wire 10. Rubber band
The small piston. is displaced when either piston is pushed inward. such as oil. in the form of work in this case. One part of the system is a piston acting as a pump. It uses the hydraulic equivalent of a mechanical lever. and was also known as a Bramah press after the inventor. He invented and was issued a patent on this press in 1795. the other part is a piston with a larger area which generates a correspondingly large mechanical force. the small piston must be moved a large distance to get the large piston to move significantly. Work is force times distance. Only small-diameter tubing (which more easily resists pressure) is needed if the pump is separated from the press cylinder. This is how energy. which is proportional to the ratio of areas of the heads of the pistons. Therefore. A fluid. of England. is conserved and the Law of Conservation of Energy is satisfied. and since the force is increased on the larger piston. Pascal's law: Pressure on a confined fluid is transmitted undiminished and acts with equal force on equal areas and at 90 degrees to the container wall. displaces a smaller amount of volume than the large piston. The distance the large piston will move is the distance that the small piston is moved divided by the ratio of the areas of the heads of the pistons.CHAPTER 2 HYDURALIC A hydraulic press is a machine (see machine press) using a hydraulic cylinder to generate a compressive force. with a modest mechanical force acting on a small cross-sectional area. he studied the existing literature on the motion of fluids and put this knowledge into the development of the press PRINCIPLE The hydraulic press depends on Pascal's principle: the pressure throughout a closed system is constant. the distance the force is applied over must be decreased. Joseph Bramah. for a given distance of movement. PASCALS LAW Pascal's law or the principle of transmission of fluid-pressure is a principle in fluid mechanics that states that . As Bramah (who is also known for his development of the flush toilet) installed toilets.
g is acceleration due to gravity (normally using the sea level acceleration due to Earth's gravity in metres per second squared). or the difference in elevation between the two points within the fluid column (in metres in SI). is the height of fluid above the point of measurement.pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure ratio (initial difference) remains the same. DEFINITION Pascal's principle is defined A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid This principle is stated mathematically as: where is the hydrostatic pressure (given in pascals in the SI system). Note that the variation with height does not depend on any additional pressures. EXPLAINATION If a U-tube is filled with water and pistons are placed at each end. ρ is the fluid density (in kilograms per cubic meter in the SI system). or the difference in pressure at two points within a fluid column. Therefore Pascal's law can be interpreted as saying that any change in pressure applied at any given point of the fluid is transmitted undiminished throughout the fluid. The intuitive explanation of this formula is that the change in pressure between two elevations is due to the weight of the fluid between the elevations. [1] The law was established by French mathematician Blaise Pascal. pressure exerted against the left . due to the weight of the fluid.
piston will be transmitted throughout the liquid and against the bottom of the right piston. (The pistons are simply "plugs" that can slide freely but snugly inside the tube. The input force multiplied by the distance moved by the smaller piston is equal to the output force multiplied by the distance moved by the larger piston. Pascal's principle underlies the operation of the hydraulic press. in turn. or 0. the larger piston will support a 500 kg load .) The pressure that the left piston exerts against the water will be exactly equal to the pressure the water exerts against the right piston. Forces can be multiplied using such a device. The oil. which lifts the automobile. transmits the pressure to a piston. by any amount. Suppose the tube on the right side is made wider and a piston of a larger area is used. because a decrease in distance moved compensates for the increase in force. A typical application of Pascal's principle for gases and liquids is the automobile lift seen in many service stations (the hydraulic jack). Pascal's principle applies to all fluids. Increased air pressure produced by an air compressor is transmitted through the air to the surface of oil in an underground reservoir. The difference between force and pressure is important: the additional pressure is exerted against every square centimeter of the larger piston. The hydraulic press does not violate energy conservation. The relatively low pressure that exerts the lifting force against the piston is about the same as the air pressure in automobile tires. By further increasing the area of the larger piston (or reducing the area of the smaller piston). 50 times as much force is exerted on the larger piston. an additional pressure (nearly 1 N/cm 2) due to the weight of the load is transmitted throughout the liquid and up against the larger piston. Hydraulics is employed by modern devices ranging from very small to enormous. the large piston will be raised only one-fiftieth of this. forces can be multiplied. this is one more example of a simple machine operating on the same principle as a mechanical lever. for example. there are hydraulic pistons in almost all construction machines where heavy loads are involved. One newton input produces 50 newtons output. APPLICATION . in principle.2 centimeters. whether gases or liquids. the piston on the right has 50 times the area of the piston on the left.fifty times the load on the smaller piston. Since there is 50 times the area. Thus. When the small piston is moved downward 10 centimeters. If a 10 kg load is placed on the left piston. For example.
325 kPa or 1013. inventor. Scuba divers must understand this principle.[1] named after the French mathematician. stress. writer. or alternatively solely SI base units.000 Pa). [2] The kilopascal is used in other applications such as inflation guidance markings on bicycle tires. One hectopascal is equivalent to one millibar. one kilopascal is about 1% of atmospheric pressure. standard atmospheric pressure is 101. internal pressure. defined as one newtonper square meter. kg is the kilogram and s is the second.[3] One hectopascal corresponds to about 0. one standard atmosphere is exactly equal to 101. and increases by about 100 kPa for each increase of 10 m depth PASCAL The pascal (symbol: Pa) is the SI derived unit of pressure. water towers. kilopascal (1 kPa ≡ 1000 Pa). Used in artesian wells. and philosopher Blaise Pascal. DEFINITION The pascal can be expressed using SI derived units.25 hPa or 101325 Pa. physicist.000 Pa).325 Pa.1% of atmospheric pressure slightly above sea level. and gigapascal (1 GPa ≡ 1. Common multiple units of the pascal are the hectopascal (1 hPa ≡ 100 Pa).000. and dams.000. The corresponding Imperial unit is pounds per square inch (psi).• • • • • The siphon The underlying principle of the hydraulic jack and hydraulic press Force amplification in the braking system of most motor vehicles. m is the meter.000. Meteorological barometric pressure reports typically report atmospheric pressure in hectopascals. pressure is twice the atmospheric pressure at sea level. megapascal (1 MPa ≡ 1. Young's modulus and tensile strength. It is a measure of force per unit area. On Earth. . as: [4] Where N is the Newton. At a depth of 10 meters under water.
This SI unit is named after Blasé Pascal.69595 1.450377×10−4 750.22334 ≡ 106 dyn/cm2 1.06 735.5592 14.01325 1.03069×10−2 6.315789×10−3 ≈ 1 mmHg 7. As with every International System of Units (SI) unit whose name is derived from the proper name of a person.933678×10−2 ≡ 1 lbF/in2 1 psi 6.9678411 7.8046×10−2 51.8692×10−6 0. except in a situation where any word in that position would be capitalized.2. Pressure units pascal bar technical atmosphere standard atmosphere torr pounds square inch per Pa bar at atm Torr psi 1 Pa ≡ 1 N/m2 1 bar 105 1 at 1 0.333224×10−3 1.0197 0.980665 ×10 5 10−5 1. —Based on The International System of Units.8948×10−2 . However.98692 0.01325 atm ×105 1 Torr 133.5006×10−3 1.8948×103 6. section 5.0197×10−5 9.359551×10−3 1. Note that "degree Celsius" conforms to this rule because the "d" is lowercase. it should always begin with a lower case letter (Pascal).71493 1. when an SI unit is spelled out in English. such as at the beginning of a sentence or in capitalized material such as a title.0332 ≡ p0 ≡ 760 14.50377 14. the first letter of its symbol is upper case(Pa).3224 1.980665 ≡ 1 kp/cm2 1.
magnetic. measures liver stiffness in kiloPascals. The pascal is also equivalent to the SI unit of energy density.0665 kPa.80665 Pa).Uses The pascal (Pa) or kilopascal (kPa) as a unit of pressure measurement is widely used throughout the world and has largely replaced the pounds per square inch (psi) unit. andgravitational fields. tooth enamel at 83. except in some countries that still use the Imperial measurement system. megapascals (MPa = N/mm2) or gigapascals (GPa = kN/mm 2) are commonly used to measure stiffness or tensile strength of materials. Other. hemp (fibre) at 58. aluminium at 69.[6] but is it often rounded off to 100 kPa in practice. the unit of pressure is the barye (symbol ba). a non-invasive method for estimating the extent of liver fibrosis. Transient elastography (FibroScan). steel at approximately 200. In the former mts system. the unit of pressure is the pièze (symbol pz). which is equal to one kilopascal. which is equal to one decipascal. Tectonophysicists use the gigapascal (GPa) in measuring or calculating tectonic forces within the earth.2 inches of water CHAPTER 3 FLUID STATICS . copper at 117. older units of measure occasionally used for pressure are millimeters of mercury (Torr) and millimetres of water (1. This applies not only to the thermodynamics of pressurized gasses. Examples of (approximate) tensile modulus for several common substances (in megapascals) include nylon at 2-4. The older kilogram-force per square centimetre corresponds to 98. but also to the energy density of electric. In materials science. and diamond at 1220. silkworm silk at 500. In the cgs system.0 mmH2O = 9. J/m3. Airtightness testing of buildings is measured at 50 Pa or 0.
F: force normal to areaA. transporting and using fluids.Fluid statics or hydrostatics is the branch of fluid mechanics that studies fluids at rest. A: area). Archimedes is credited with the discovery of the mathematical law that bears his name. . that relates the buoyancy force to the volume and density of the displaced fluid. It embraces the study of the conditions under which fluids are at rest in stable equilibrium. It is also relevant to geophysicsand astrophysics (for example. and the only force acting on any such small cube of fluid is the weight of the fluid column above it. and is contrasted with fluid dynamics. the engineering of equipment for storing. Hydrostatics offers physical explanations for many phenomena of everyday life. and why the surface of water is always flat and horizontal whatever the shape of its container. to meteorology. to medicine (in the context of blood pressure). The hydrostatic pressure can be determined from a control volume analysis of an infinitesimally small cube of fluid. Hydrostatics is fundamental to hydraulics. the study of fluids in motion. by the builders of boats. why wood and oil float on water. in understanding plate tectonics and the anomalies of the Earth's gravitational field). aqueducts and fountains. with p: pressure. such as why atmospheric pressure changes with altitude. HISTORY ome principles of hydrostatics have been known in an empirical and intuitive sense since antiquity. and many other fields. HYDROSTATIC PRESSURE Hydrostatic pressure is the pressure exerted by a fluid at equilibrium due to the force of gravity. cisterns. The Roman engineer Vitruvius warned readers about leadpipes bursting under hydrostatic pressure[1] The concept of pressure and the way it is transmitted by fluids were formulates by the French mathematician and philosopher Blaise Pascal in 1647. Since pressure is defined as the force exerted on a test area ( p = F/A. [2] A fluid in this condition is known as a hydrostatic fluid. hydrostatic pressure can be calculated according to the following formula: .
such as forces on dams. buoyancy and hydraulic actuation. z0 is the height of the zero reference point of the pressure (m). g is gravitational acceleration (m/s2). Note that this reference point should lie at or below the surface of the liquid. not just water.where: • • • • • • p is the hydrostatic pressure (Pa). (The same assumption cannot be made within a gaseous environment. this integral can be simplified significantly for many practical applications. one can neglect the variation of g. however. one that can be understood easily and completely from a very few fundamentals. A is the test area (m2). and in which the predictions agree closely with . The study yields many useful results of its own. and is well worth studying for such practical reasons. since the height h of the fluid column between z and z0 is often reasonably small compared to the radius of the Earth. based on the following two assumptions: Since many liquids can be consideredincompressible. For water and other liquids. ρ is the fluid density (kg/m3). the absolute pressure compared to vacuum is: Hydrostatics is about the pressures exerted by a fluid at rest. Otherwise. the integral boils down to the simple formula: where h is the height z − z0 of the liquid column between the test volume and the zero reference point of the pressure. one has to split the integral into two (or more) terms with the constant ρliquid and ρ(z')above.) Also. a reasonably good estimation can be made from assuming a constant density throughout the liquid. It is an excellent example of deductive mathematical physics. Under these circumstances. Any fluid is meant. For example. It is usually relegated to an early chapter in Fluid Mechanics texts. z is the height (parallel to the direction of gravity) of the test area (m). since its results are widely used in that study.
though the rock there can flow like a liquid when considered over centuries. and rock will flow over hundreds of years. ice. There are several familiar topics in hydrostatics which often appear in expositions of introductory science. Geology has now shown us clearly that there are substances which can resist shearing forces over short time intervals. propagate deep in the earth. available to the student. and which are also of historical interest that can enliven their presentation.experiment. so that pressures are normal to confining surfaces. A ball of pitch. as shown in glaciers. A great deal can be done with only elementary mathematics. Shear earthquake waves. as in convection in the mantle of the earth. The following will be discussed briefly here: • • • • • • Pressure and its measurement Atmospheric pressure and its effects Maximum height to which water can be raised by a suction pump The siphon Discovery of atmospheric pressure and invention of the barometer Hydraulic equivalent of a lever . The rate of shearing may not be strictly proportional to the stress. will spread out and flow in months. the material can be used from the earliest introduction of school science. with periods of seconds. It is usually stated that a fluid is a substance that cannot resist a shearing stress. and appear to be typical solids. competing with electrical resistivity. which can be shattered by a hammer. Viscosity may be the physical property that varies over the largest numerical range. Properly adapted. There are few better illustrations of the use of the integral calculus. Although time is not a factor in hydrostatics. The definition of a fluid deserves careful consideration. giving an excellent example of a quantitative science with many possibilities for hands-on experiences. a typical solid. as well as the principles of ordinary statics. and even rock. Ice. Such materials include wax and pitch. it enters in the approach to hydrostatic equilibrium. but which flow like liquids over long time intervals. will flow in a period of years. but exists even with low stress.
therefore. such as molasses. Water and air have low viscosity. the ideal gas laws. but they are no less fluids. that is. Hydrostatics is a very concrete science that avoids esoteric concepts and advanced mathematics. It is also much easier to demonstrate than Newtonian mechanics. Water has a definite volume. the forces exerted by heavy liquids on their containers. A fluid. time-independent states of fluids. it may also be interesting to study the volumes and areas of certain shapes. and hygrometry. Such a force is proportional to the area on which it is exerted. layers of them slide very easily on one another. We can imagine any surface in a fluid as dividing the fluid into parts pressing on each other. Pressure By a fluid. not just at the . we have a material in mind like water or air. air does not. Hydrostatics deals with permanent. the velocity of sound. At a beginning level. as if it were a thin material membrane. and they quickly assume their permanent shapes when disturbed by rapid flows. but both are fluids. may have high viscosity and take a long time to come to equilibrium. The coefficient of viscosity is the ratio of the shearing force to the velocity gradient. is a substance that cannot exert any permanent forces tangential to a boundary. and so think of the pressure at any point in the fluid. or at a more advanced level. while air is very compressible. and is called a pressure. two very common and important fluids. Any force that it exerts on a boundary must be normal to the boundary. so viscosity does not appear.• • • • • • Pumps Forces on a submerged surface The Hydrostatic Paradox Buoyancy (Archimedes' Principle) Measurement of Specific Gravity References A study of hydrostatics can also include capillarity. These interesting applications will not be discussed in this article. except as discussed in the Introduction. Water is incompressible. Other fluids.
15 ft/s2. and the pressure as a function of depth h is p = ρgh + p0. On earth. Therefore. or slug/ft3. This demonstration is similar to the usual one using a . the equilibrium of forces would not be disturbed. Gravitation is an example of a body force that disturbs the equality of pressure in a fluid.9 ft of water. in order to support the water above. and if no other forces are acting on the body of the fluid. The presence of the gravitational body force causes the pressure to increase with depth. and has a magnitude γ = ρg per unit volume. A section of the toroid was identified. If the fluid is incompressible. kg/m3. This is simply 2117 / 62. This is the maximum height to which water can be raised by a suction pump. Lord Kelvin) illustrated the equality of pressure by a "curtain-ring" analogy shown in the diagram. or lb/ft3 (pcf). fluids are also subject to the force of gravity. or its specific weight is 62. the mass per unit volume. The forces exerted on the curved surfaces have no component along the normal to a plane section.7 psi. We may ask what depth of water gives the normal sea-level atmospheric pressure of 14. and its equilibrium was analyzed. and the same in any direction at a point (Pascal's Principle). since the fluid represented by the curtain ring was in equilibrium. can be supported by atmospheric pressure. N/cm2 (pascal). or. is useful in reasoning about forces in fluids. or 2117 psf. more correctly. We call this relation the barometric equation. pounds/in2 (psi) or pounds/ft2 (psf). which acts vertically downward. In order for any small element of the fluid to be in equilibrium. according to the equation dp = ρg dh. ρ is the density. This can be extended to any direction whatever.4 = 33.boundaries. for when this equation is integrated. in this case the pressure will be the same throughout the fluid. The axiom that if a certain volume of fluid were somehow made solid. we find the variation of pressure with height or depth. imagined to be solidified. so the pressures at any two points of a plane must be equal.4 pcf. where g is the acceleration of gravity. the pressure must be the same at all neighbouring points. approximately 981 cm/s2 or 32. Professor James Thomson (brother of William Thomson. measured in lb/in3. The right-hand part of the diagram illustrates the equality of pressures in orthogonal directions. expressed in g/cm3. Pressure is expressed in units of force per unit area such as dyne/cm2. so Pascal's Principle is established. The density of water is about 1 g/cm 3. the pressure must be the same in all directions (or the element would move in the direction of least pressure). and γ is the specific weight. the equation can be integrated at once.
and a vacuum pump applied to the upper end. The same result can be obtained with calculus by summing the pressures and the moments. For example. The upper surface of the cylinder can be placed at the free surface if desired. passing through its centroid normal to plane AB. but below it. and the pressure at the . Atmospheric Pressure and its Effects Suppose a vertical pipe is stood in a pool of water. Note that the thrust is equal to the density times the area times the depth of the center of the area. but its line of action does not pass through the center. the thrust F on the plane is the weight of a prism of fluid of cross-section AC'D'B. When it has sucked all the air out above the water. the liquid assumes a free surface perpendicular to gravity. we see that p 2 = p1 + ρgh. The line AC' perpendicular to the plane is made equal to the depth AC of point A. the pressure on the surface of the water inside the pipe is zero. which can be proved by Thomson's method. When gravity acts. and line BD' is similarly drawn equal to BD. A straight cylinder of unit cross-sectional area (assumed only for ease in the arithmetic) can be used to find the increase of pressure with depth. the water levels outside and inside the pipe are equal. From this same figure. and passes through the center of mass of this displaced fluid. The line OD' also passes through C'. it is easy to prove Archimedes's Principle. but less transparent arguments using calculus. by proportionality of triangles OAC' and OAD'. and the pressures on the surfaces are also equal. Therefore. that the buoyant force is equal to the weight of the displaced fluid. and equal to the atmospheric pressure. Now start the pump. of course. Ingenious geometric arguments can be used to substitute for easier. O is the point at which the prolonged projection intersects the free surface. Indeed. The pressure is now the same in any direction at a point. the force on acting on one side of an inclined plane surface whose projection is AB can be found as in the diagram at the right.triangular prism and considering the forces on the end and lateral faces separately. Before we start the pump. at the center of thrust. but is greater at points that lie deeper.
An aneroid barometer is much easier to use in field observations. The instrument must be calibrated before use. at various points in the vicinity. The height differences can be calculated from h = 60. As a practical matter. such as in reconnaisance surveys. Of course. because the density of mercury depends on the temperature. for capillarity if the tube is less than about 1 cm in diameter. there is the vapour pressure of the water to worry about if you want to be precise.0 mm. and the brass scale expands. and atmospheric pressures are traditionally given in terms of the length of a mercury column.001201 mmHg at 20°C.92 in. it would be read at the start of the day at the base camp.000181792 per °C) and a brass scale (&alpha = 0. where P and p are in the same units. The materials and construction are arranged to give a low temperature coefficient. whose density at 0 °C is 13. 30 inHg (inches of mercury) had been used previously. but we neglect this complication in making our point. with a vacuum above it. In a particular case. the mercury reservoir is raised or lowered until the surface of the mercury just touches a reference point. Now do the same thing with liquid mercury. The barometer is a familiar example of this.0000184 per °C) the temperature correction is -2. We require a column of water 33.494 ft. The vapor pressure of mercury is only 0. and then finally at the starting point. In Britain. or 760. t are in °F.64)/986) feet. This definition of the standard atmospheric pressure was established by Regnault in the mid-19th century. . which is mirrored in the surface so it is easy to determine the proper position. so a correction from this source is negligible.level of the water on the outside of the pipe is still the atmospheric pressure. it is convenient to measure pressure differences by measuring the height of liquid columns. This movement is communicated to a needle that revolves in a dial.360 log(P/p) [1 + (T + t . to balance the atmospheric pressure.5951 times that of water. 29. the barometric tube. and even slightly for altitude. closed at one end.74 mm at 760 mm and 20°C.9 ft high inside the pipe. and is usually arranged to read directly in elevations. For the usual case of a mercury column (α = 0. Before reading the barometer scale. a practice known as manometry. is filled with mercury and then inverted and placed in a mercury reservoir. since the value of g changes with altitude. and T. An aneroid barometer uses a partially evacuated chamber of thin metal that expands and contracts according to the external pressure. Corrections must be made for temperature. To make a barometer. to determine the change in pressure with time. The height of the column is 2.
33 psi. A vacuum of 25 inches is the same thing as an absolute pressure of 5 inches (of mercury). while a gauge pressure is referred to the atmospheric pressure at the moment. The analysis of the siphon is easy. Pressures are very frequently stated in terms of the height of a fluid. or 4. normally rising higher than the water levels in the two containers. Water flowing in a pipe is subject to head loss because of friction. the tube can be placed in one fluid and filled by sucking on it. the other end is put in place." and the factor connecting the head and the pressure is the weight density ρg. this means the pressure below the atmospheric pressure of about 30 in. In the diagram. A siphon can be made by filling the tube. Another application of pressure is the siphon. it is called an inverted siphon. until the levels are equal. A head of 10 ft is equivalent to a pressure of 624 psf. It is always a little surprising to see that the jar does not empty itself. Take a jar and a basin of water. and then putting the ends under the surface on both sides. It can also be considered an energy availability of ft-lb per lb. fluid flows from the basin with the higher level into the one with the lower level. Water with a pressure head of 10 ft can furnish the same energy as an equal amount of water raised by 10 ft. If it is the same fluid whose pressure is being given. When a siphon goes below the free water levels. When it is full. This is a tube filled with fluid connecting two containers of fluid. about 34 feet. In fact. at least to pass over their rims. Fill the jar with water and invert it under the water in the basin. The name is Greek for the tube that was used for drawing wine from a cask. so there will be no flow. and should be obvious. Now raise the jar as far as you can without allowing its mouth to come above the water surface. In the English engineer's system. When a vacuum is stated to be so many inches. If the levels in the two basins are not equal. and as much water leaves as air enters. There is obviously a maximum height for the siphon which is the same as the limit of the suction pump. By blowing through a straw.An absolute pressure is referred to a vacuum. . The pressure rises or falls as described by the barometric equation through the siphon tube. A negative gauge pressure is a (partial) vacuum. weight density is in pounds per cubic inch or cubic foot. it is usually called "head. It is good to remind oneself of exactly the balance of forces involved. closing the ends. this is a famous method of collecting insoluble gases in the chemical laboratory. Alternatively. one can put air into the jar. or for supplying hummingbird feeders. the two water levels are the same. but the water remains with no visible means of support.
A thermal siphon is a means to circulate a liquid by convection. which supplies water to Boston. or the discharge from an orifice. Mariotte's Bottle. An ingenious way to arrive at this is shown in the figure. This would make a good experiment to verify the relation V = √(2gh) since h and the horizontal distance reached by the jet for a given fall can both be measured easily. As the level in the supply container falls. None of these arrangments is actually a siphon in the physicist's sense.Inverted siphons (which are really not siphons at all) are sometimes used in pipelines to cross valleys. The head available at the nozzle as shown is equal to h. includes pumped siphons. vacuum breakers may be used at high points to prevent this. The Quabbin Aqueduct. and then the vacuum causes the water to descend again when the heat is removed (invented by Löff in 1830). Siphons work because of atmospheric pressure. do use the siphon principle. A soda siphon is a source of carbonated water. In the case of water. especially in plumbing. so the fluids must be pressurized by pumps so the pressure does not fall to zero at the crests. In some cases. while siphon coffee (or vacuum coffee) is made in an apparatus where the steam from boiling water pushes hot water up above the coffee and filter. and perhaps Thomson's siphon recorder of 1858. especially when it may allow dirty water to mix with clean. siphon action is not desired. In biology. A partial vacuum is created in the air space by the fall of the water level exactly equal to the pressure difference between the surface and the end of the open tube connecting to the atmosphere. The occasional spelling "syphon" is not supported by the Greek source. Mercury. The siphon tube used in irrigation. therefore. Differences in elevation are usually too great to use regular siphons to cross hills. The pressure at this point is. The plug must seal the air space at the top very well. In these cases. the pressure difference decreases. pressure reduction would eventually reach the vapor pressure and the water would boil. The term "siphon" is often used in a different sense. which has a very low vapor pressure. maintained at atmospheric while water is delivered. one would like a source that would provide a constant pressure at the outlet of the siphon. a siphon is simply a tubular structure. would simply separate leaving a . In some cases. and would not operate in a vacuum.
making the first vacuum pump. but it was the closest. Pascal's experimentum crucis is one of the triumphs of early modern science. Torricelli's doctrine had triumphed over the Church's support for horror vacui. which he used in vivid demonstrations of the pressure of the atmosphere to the Imperial Diet at Regensburg in 1654. Evangelista Torricelli (1608-1647). This was one of the first victories for rational physics over the illusions of experience. As the large container is filled with . A liquid column is unstable under a negative pressure. an extinct volcano in the Auvergne just west of his home of Clermont-Ferrand in 1648 by Périer. Clermont is now the centre of the French pneumatics industry. took up the cause. An original vacuum pump and hemispheres from 1663 are shown at the right (photo edited from the Deutsches Museum. not by horror vacui as Aristotle had supposed. 8 on each side. with the upper branch open to the atmosphere. Pascal had a barometer carried up the 1465 m high Puy de Dôme. Burgomeister of Magdeburg. The Puy de Dôme is not the highest peak in the Massif Central--the Puy de Sancy. in England. Galileo's student and secretary. Torricelli's early death was a blow to science. The two beakers of mercury are connected by a three-way tube as shown. Robert Hooke (1635-1703) made a vacuum pump for Robert Boyle (1627-1691). by means of the apparatus shown at the left. his brother-in-law. Famously. at 1866 m is. The siphon would be re-established if the pressure is restored. Saxony. a member of the Florentine Academy of Experiments. invented the mercury barometer in 1643. By this time. and is well worth consideration. he evacuated a sphere consisting of two well-fitting hemispheres about a foot in diameter. but his ideas were furthered by Blaise Pascal (1623-1662). not by horror vacui. and how much force it did require to separate evacuated hemispheres. The remarkable Otto von Guericke (1602-1686). Christian Huygens (1629-1695) became interested in a visit to London in 1661 and had a vacuum pump built for him. Pascal demonstrated that the siphon worked by atmospheric pressure. and brought the weight of the atmosphere to light. Then. could not pull them apart. He also showed that air had weight. see link below).Torricellian vacuum. The mercury column was held up by the pressure of the atmosphere. and showed that 16 horses.
As we have seen. though it seems so. or ln(p/p0) = -Mgh/RT.5°C/km up to an altitude of about 11 km at middle latitudes. which is by no means incompressible. The fluid in question here is air. When the state shown is reached.333 mmHg = 100 Pa = 1000 dyne/cm 2. and is about 8 km at T = 273K. A kilogram-force per square centimeter is 981.water. Then the change of pressure in a change of altitude dh is dp = -ρg dh = -(pM/RT)gdh. easily measurable with a chemical balance. As we rise in the atmosphere and the pressure decreases. a newton per square metre or 10 dyne/cm 2. The quantity H = RT/Mg is called the "height of the homogeneous atmosphere" or the scale height. Of course. the real atmosphere is by no means isothermal close to the ground. and Pascal also has been honoured by a unit of pressure. The pressure of the atmosphere is also considerable. so air is by no means even approximately weightless. like being 34 ft under water. mb. In meteorolgy. not the American short ton. but cools with height nearly linearly at about 6.000 dyne/cm2. This is a little harder to integrate than before. Above this is a region of . the air also expands.293 kg. the millibar. it could have flowed in at will to soothe itself. For example.293 mg under standard conditions. A cubic centimetre of air weighs 1. The ton in this case is 2240 lb. is used.5 psi (about an atmosphere!). and a cubic metre 1. tons per square inch has been used for large pressures. In Europe. To see what happens in this case. very close to a standard atmosphere. and assume that the temperature T is constant. 1 mb = 1. The weight of a sphere of air as small as 10 cm in diameter is 0. In an isothermal atmosphere. the pressure decreases exponentially. 1 tsf = 15. pressure on the free surfaces of the mercury in the beakers pushes mercury into the tubes. 1 psi = 51. 1 tsi = 2240 psi. and this figure can be used to find other approximate equivalents. p = ρRT/M. which is 1. as in tire pressures and other engineering applications. the beakers are connected by a mercury column.7 mmHg. The mercury has been open to the atmosphere all this time. In Britain. This quantity gives the rough scale of the decrease of pressure with height. also close to one atmosphere.7 psi. called the tropopause. but we do not notice it. it has been considered approximately 1 atm. in English units the atmosphere is about 14. we can make use of the ideal gas equation of state. but the result is ln p = -Mgh/RT + C. The mm of mercury is sometimes called a torr after Torricelli. or dp/p = -(Mg/RT)dh. so if there were any horror vacui. and the siphon starts.01325 bar. or finally p = p0exp(-Mgh/RT). emptying the upper beaker and filling the lower. A bar is 106 dyne/cm2.68 g.
If you live at a high altitude. we can find the pressure by numerical integration quite easily. At an elevation of 1500 m (near Denver. in both cylinders. you may well find that it is closer to 25 inches. but if you have a real barometer. which generally move at right angles to the direction of most rapid change of pressure. and how they vary with time. or the top of the Puy de Dôme). The work done by the fluid in this displacement is dW = F dx = pA dx = p dV. though few people know what to do with it. then hydrostatics will still be valid. then F = pA is the force on the piston. and water boils at 95 °C. This is only an arbitrary 'fix' and leads to some strange conclusions.2 inches. The barometric pressures quoted in the news are reduced to sea level by standard formulas. p. In fact. and then at some higher level the atmosphere warms again to near its value at the surface. there are variations from the average values. 29. The atmospheric pressure is of great importance in meteorology. A process for which this is true is called quasi-static. that is. The barometric pressure may be given in popular weather forecasts. along the isobars. If the fluid is . such as the permanent winter highs above high plateaus that are really imaginary. then the change in volume is dV = A dx. Certain typical weather patterns are associated with relatively high and relatively low pressures. possibly of different areas A and A'. Of course. Now consider two cylinders. which are contours of constant pressure. that amount to assuming that there is a column of air from your feet to sea level with a certain temperature distribution. and p the pressure of the fluid in it. a mechanism for transforming pressure to force. the stratosphere. Then the pressure is the same.nearly constant temperature. When the temperature profile with height is known. altitude is quite a problem in meteorology. If A is the area of the cylinder. For simplicity. the atmospheric pressure is about 635 mm. connected with each other and filled with fluid. say. If the movement is slow enough that inertia and viscosity forces are negligible. and adding the weight of this column to the actual barometric pressure. The Hydraulic Lever A cylinder and piston is a chamber of variable volume. since pressures must be measured at a common level to be meaningful. since it determines the winds. your local weather reporter may report the pressure to be. suppose that there are no gravitational forces. If the piston moves outwards a distance dx.
More complicated pumps have valves allowing them to work repetitively. p' = p + ρgh. which means that dynamic or inertia forces are negligible. filled by withdrawing the piston and emptied by pressing it back in. These are usually check . or the net work done in the process is p' dV' + p dV = -dM gh. as its port is immersed in the fluid or removed from it. We have already seen an important example of this in the hydraulic lever or hydraulic press. hydrostatic or positive displacement pumps. Pumps are seen to fall within the province of hydrostatics if their operation is quasi-static. Pumps Pumps are used to move or raise fluids. the same as the ratio of the areas. The most famous application of this principle is the Bramah hydraulic press. This was the crucial problem that Bramah solved by his leather seal that was held against the cylinder and the piston by the hydraulic pressure itself. but are excellent examples of hydrostatics. where dM is the mass of fluid displaced from the lower cylinder to the upper cylinder. This says the work done on one piston is equal to the work done by the other piston: the conservation of energy.(ρ dV)gh. such as centrifugal pumps. who also invented many other useful machines. invented in 1785 by Joseph Bramah (1748-1814). The ratio of the forces on the pistons is F' / F = A' / A. Here we will only consider positive displacement pumps. what was remarkable was to find a way to seal the large cylinder properly. Again. In the presence of gravity. Now. so that dW = p dV + p dV' = F dx + F' dx' = 0. energy is conserved if we take into account the potential energy of the fluid. They are not only very useful. They have a piston (or equivalent) moving in a closely-fitting cylinder. Pumps are of two general types. then dV + dV' = 0. which we have called quasi-static. and the ratios of the displacements dx' / dx = F / F' = A / A' is in the inverse ratio of the areas. This mechanism is the hydrostatic analogue of the lever. it was not very remarkable to see the possibility of a hydraulic press. Now. and is the basis of hydraulic activation. and pumps depending on dynamic forces. where h is the difference in elevation of the two cylinders. which can be understood purely by hydrostatic considerations. The simplest pump is the syringe. including a lock and a toilet. and forces are exerted on the fluid by motion of the piston.incompressible. p' dV' = -dV (p + ρgh) =-p dV .
The force pump. their place taken by the sliding contact between the rotors and the housing. as in the case of a diesel engine injector. The bicycle pump uses the valve on the valve stem of the tire or inner tube to hold . Another valve can be placed at the nozzle if required. The force and lift pumps are typically used for water. as for fire fighting. in large volumes. The force pump has two check valves in the cylinder. The force pump has two valves in the cylinder. requiring no accurate machining. Diaphragm pumps are force pumps in which the oscillating diaphragm takes the place of the piston. or "suction. however. Fire fighting force pumps usually had two cylinders feeding one receiver alternately. to produce a jet. The delivery in this case is from the upper part of the cylinder which the piston does not enter. The bellows is a very old device. The maximum lift. the delivery valve when the cylinder volume decreases." is determined by the atmospheric pressure. but would be equally applicable to liquids. or by the pressure of the fluid on one side of the diaphragm. The valve can be a piece of soft leather held close to holes in the chamber. The diaphragm may be moved mechanically. There are many kinds of valves. The supply valve opens when the cylinder volume increases. and a valve in the piston that allows the liquid to pass around it when the volume of the cylinder is reduced. The single valve is in one or both sides of the expandable chamber. The Roots blower can either exhaust a receiver or provide air under moderate pressure. The lift pump has a supply valve. The air space in the receiver helped to make the water pressure uniform. and either cylinder must be within this height of the free surface. one for supply and the other for delivery. A nozzle can be used to convert the pressure to velocity. while the lift pump has a one valve in the cylinder and one in the piston. The Roots blower has no valves. and close automatically to prevent reverse flow. The three pumps on the right are typically used for air. Some positive displacement pumps are shown at the right. can give an arbitrarily large pressure to the discharged fluid. and they are usually the most trouble-prone and complicated part of a pump.valves that open to allow passage in one direction.
water entered the pump chamber through a clack. the heavy timber pump rods did the actual pumping. the piston lifted the column of water above it. but allows air to pass when the movement is reversed. when it descended. The . The piston could only "suck" water 33 ft. as in the bucket pump. Diaphragm and vane pumps are not shown. The piston. which we recognize as lift pumps. A plunger displaced volume in a chamber. On the down stroke. In this case. At the same time. it was not necessary that it fit the cylinder accurately. the limit set by the valves. which could be of any length. a very necessary process as mines became deeper. The first engine may have been erected in Cornwall in 1710. where it would be ready to make another lift. A special application for pumps is to produce a vacuum by exhausting a container. forcing the water in it through a check valve up the shaft. but this occurred at the bottom of the shaft. also placed at the bottom of the shaft. but they act the same way by varying the volume of a chamber. with the pistons somewhat miscalled buckets. More satisfactory were the plunger pumps. the engine at the surface lifted the heavy pump rods on the up-stroke. but the Dudley Castle engine of 1712 is much better known and thoroughly documented. The first pumps used in Cornwall were called bucket pumps. and directing the flow with check valves. a clack in the bucket opened. of course. called the receiver. so this was only a limit on the piston stroke. When it rose.pressure in the tire. designed in the 18th century. borne down by their weight. when a clack in the bottom of the pipe opened and allowed water to enter beneath the piston. or 28 ft more practically. Newcomen's atmospheric engine was invented to supply the power for pumping. Hawksbee's dual cylinder pump. They pumped on the up-stroke. allowing it to sink through the water to the bottom. A good pump could probably reach about 5-10 mmHg. which is attached to the discharge tube. Only the top of the plunger had to be packed. When the atmospheric engine piston returned. Pumps were applied to the dewatering of mines. is the final form of the air pump invented by Guericke by 1654. has a flexible seal that seals when the cylinder is moved to compress the air.
Langmuir's mercury diffusion pump. A search of the museum website did not reveal any evidence of it. The bell-jar receiver. motor-driven rotary-seal pumps sealed by running in oil are used for the same purpose. . It is operated by pushing and pulling the handle H. At the right is Sprengel's pump. with four cylinders and driven by a water wheel. It looks like a steam engine. filling with the low-pressure air from the receiver. but it is very slow and can only evacuate small volumes. so it could probably reach about 1 mmHg. used to turn a large head (pressure) of water into rotary motion. piston A is descending. a vacuum of about 1 μm can be obtained with a Sprengel pump. Richard Trevithick. and placed in service in 1917. A few very impressive column of water engines were made in the 19th century. and led to oil diffusion pumps that can reach very high vacua. is shown. V'. Later. However. previously. It has no valves on the low-pressure side. This engine was exhibited in the Deutsches Museum in München as late as 1977. with the valves replaced by drops of mercury. jsut exhaust valves V. while piston B is rising. also built by von Reichenbach was found. invented by Huygens. a cumbersome globe was the usual receiver.cooperation of the cylinders made the pump much easier to work when the pressure was low. but they were never popular and remained rare. replaced Sprengel pumps. and moves slowly down the fall tube as mercury is steadily added. helped by the partial vacuum remaining below it. Small amounts of gas are trapped at the top of the fall tube as the mercury drops. of course. as for lifting. but of course is not a heat engine and can be of high efficiency. it is not of as high efficiency as a turbine. but has the advantage that it can be operated at variable speeds. The photograph at the right shows a column-of-water engine built by Georg von Reichenbach. Theoretically. famous for high pressure steam engines. The column of water or hydrostatic engine is the inverse of the force pump. coming out at the bottom carrying the air with it. In the diagram. which was much faster. At the present day. but a good drawing of another brine pump. Tate's air pump is a 19th century pump that would be used for simple vacuum demonstrations and for utility purposes in the lab. The length of the fall tube must be greater than the barometric height. It was used to pump brine for the Bavarian state salt industry. and is much more complicated. with valves operated by valve gear. This machine. also built hydrostatic engines in Cornwall.
King of Bavaria. The pipeline was further extended to Rosenheim. These engines are brass to resist corrosion by the salt water. Maximilian I. This was a much easier way to mine salt than underground mining. Forces on Submerged Surfaces Suppose we want to know the force exerted on a vertical surface of any shape with water on one side. elevation 470 m. over a summit 943 m high. at 24% to 26% (saturated is 27%) salt. He was associated with Joseph Fraunhofer. which is easier but not as illuminating. If the surface is not symmetrical. entering service in 1816. and abrupt changes of rate of flow must not be made. Fresh water was also allowed to flow down to the salt beds. entered service in 1821. that from ancient times had been evaporated over wood fires. in southeastern Bavaria. fourbarrel pump. Von Reichenbach is said to have built this pipeline. so both valves must not close at the same time. near Salzburg. The name derives from "rich in salt. we can find the total force F. the position of the total force in the transverse direction can be . elevation 530 m." This famous salt region had salt springs flowing nearly saturated brine.a Solehebemaschine ("brine-lifting machine"). in 1818-10. The salt industry of Bad Reichenhall still operates. c = M / F. Georg von Reichenbach (1771-1826) is much better known as an optical designer than as a mechanical engineer. commissioned von Reichenbach to bring brine from Berchtesgaden. or manager of the state salt works. and the pressure on the surface of the water zero. since wood fuel for evaporating the brine was exhausted in Reichenhall. and was Salinenrat. where there was turf as well as wood. but it is now Japanese-owned. It had two pressureoperated poppet valves for each cylinder. Water pressure engines must be designed taking into account the incompressibility of water. and they died within days of each other in 1826. now Bad Reichenhall. assuming gravity to act. which was centred on the town of Reichenhall. A brine pipeline to Traunstein was constructed in 1617-1619. for which he designed a water-wheel-driven. We have already solved this problem by a geometrical argument. The force on a small area dA a distance x below the surface of the water is dF = p dA = ρgx dA. By integration. and the brine was then pumped to the surface. to Reichenhall. He was of an aristocratic family. The pump shown in the photograph pumped brine over this line. Air chambers can be used to eliminate shocks. but now we apply calculus. and the moment of this force about a point on the surface is dM = px dA = ρgx2 dA. and the depth at which it acts.
The horizontal forces exerted by the water on the two sides must be equal and opposite. If the side is inclined outwards. If there happens to be a pressure on the free surface of the water. The simplest case is a rectangular gate of width w. the result is demanded by ordinary statics.' It was conceived by the celebrated Flemish engineer Simon Stevin (1548-1620) of Brugge. In this case. filled with water. If the side is inclined inwards. M = ρgw[(h + H)3 . then the forces due to this pressure can be evaluated separately and added to this result. there is no change to this result. and third sides inclined outwards. The tanks do not contain the same weight of water. or the tank would scoot off. If we take the atmospheric pressure to act not only on the surface of the water.obtained from the integral of dM' = ρgxy dA. What we have here has been called the 'hydrostatic paradox. the first modern scientist to investigate the statics of fluids and solids. then there must be a downwards vertical force equal to the weight of the water above it. with one side vertical but the opposite side inclined inwards or outwards. Sometimes the forces are required on curved surfaces. But suppose that one tank has vertical sides. and a moment e qual to the product of this force and the distance to the centroid of the surface. or two-thirds of the way from the top to the bottom of the gate. but also the dry side of the gate.h2]/2 = ρgH(H + 2h)/2 = ρg(h + H/2)Hw. the integrations are very easy. In the simple case of h = 0.h3]/3 = ρg(H2/3 + Hh + h2)Hw. yet the forces on their bottoms are equal! I am sure that you can spot the resolution of this paradox. whose top is a distance H below the surface of the water. so the vertical force on the bottom of each tank is the same. Consider a curious rectangular tank. so that c = (H2/3 + Hh + h2)/(h + H/2). and passing through the centroid of this water. and height h. there must be an upwards vertical force equal to the weight of the 'missing' water above it. and F = ρgw[(h + H) 2 . This is the reason atmospheric pressure often seems to have been neglected in solving subh problems. c = 2H/3. one has sides inclined inward. In both cases. The pressures at the bottoms are equal. Consider three tanks with bottoms of equal sizes and equal heights. We must add a force equal to the area of the surface times the additional pressure. The vertical and horizontal components . the moment about some vertical line in the plane of the surface. The total force on the gate is equal to its area times the pressure at its centre.
typical of the charming way science was made more interesting in classical times.can be found by considering the equilibrium of volumes with a plane surface equal to the projected area of the curved surface in that direction. but whether it did or not. The same can be done for a rotating fluid. and Archimedes cunningly measured its volume by the amount of water that ran off when it was immersed in a vessel filled to the brim. spheres and cones. it is necessary to sum the forces and moments numerically on each element of area. However. the ratio of the density of a substance to the density of water. A free surface now becomes perpendicular to the total acceleration. of course. was asked to determine if the goldsmith who made a golden crown for Hieron. If a volume of fluid is accelerated uniformly. Archimedes taught that a body immersed in a fluid lost apparent weight equal to the weight of the fluid displaced. these are dynamic effects and are not strictly a part of hydrostatics. Buoyancy Archimedes. The story is told by Vitruvius. This avoids the difficult . and then in water. A substitution could not be detected by simply weighing the crown. called Archimedes' Principle. The earth's atmosphere is an example. since the horizontal and vertical forces are not necessarily in the same plane. In general. would give the answer. and for pure gold. it was found that the crown displaced more water than an equal weight of gold. By comparing the results for the crown. the weight per unit volume. and the pressure is proportional to the distance from this surface. The specific gravity is the weight in air divided by the loss in weight when immersed. The weight was known. the Coriolis force must also be taken into account. The general result is usually a force plus a couple. therefore. Tyrant of Syracuse. and only in simple cases can this be done analytically. had substituted cheaper metals for gold. can be determined by weighing the body in air. and had. where the centrifugal acceleration is the important quantity. Archimedes realized that finding the density of the crown. such as cylinders. may or may not actually have taken place. may often be easy to solve. the acceleration can be added to the acceleration of gravity. since it was craftily made to the same weight as the gold supplied for its construction. that is. When air moves relative to the rotating system. Simple surfaces. This story. however. so the legend runs. Specific gravity. been adulterated.
and the buoyant force tends to correct the rotation. This is just the integral calculus in action. Should the board start to rotate to one side. where V is the volume of the brick. of height h. the weight of the ship. as small as desired. and an equal volume is removed on the left. with a large rock in the boat. consider a submerged brick. while the force exerted by gravity on the boat acts through its own centre of gravity G. of the body. so the result applies in general. and can tell us why. so they do not matter. called the metacentre. width w and length l.determination of the exact volume of the sample.g.g. it is the centre of gravity of the volume V of the displaced water. so the boat will tend to capsize. If the ship heels by an angle Δθ. will naturally be higher than the c. The difference in pressure on top and bottom of the brick is ρgh. or the application of Professor Thomson's analogy. It is not as easy to make boats as it might appear. a wedge-shaped volume of water is added on the right. Let Bo be the centre of buoyancy with the ship upright. since the boat's c. Any body can be considered made up of brick shapes. What is the effect on the water level of the lake? Suppose you make a drink of ice water with ice cubes floating in it. To see how buoyancy works. The centre of buoyancy is then moved to the right to point B. We . or centre of buoyancy. The forces on the sides have no vertical components. that is. a board floats. the displaced volume immediately moves to that side. A ship with an improperly designed hull will not float. The net upward force is the weight of a volume V of the fluid of density ρ. A floating body will be stable provided the line of action of the buoyant force passes through a point M above the c. What happens to the water level in the glass when the ice has melted? The force exerted by the water on the bottom of a boat acts through the centre of gravity B of the displaced volume. γV = W. so that there is a restoring couple when the boat heels. This looks bad for the boat. Consider a man in a rowboat on a lake. Well. or heel. so the difference in total force on top and bottom of the brick is simply (ρgh)(wl) = ρgV. of the displaced water.g. He throws the rock into the water. so that V remains constant.
then the volume element is xΔθdA (this automatically makes the volume to the left of x=0 negative). The Montgolfier brothers' hot air balloon . since for small Δθ the tangent is equal to the angle. to list 80°. The ship capsized off Finisterre in 1870 in a gale when the topsails were not taken in promptly enough and the ship heeled beyond its 14° maximum. For example. In 2006. then. V(B oB) = IΔθ. Longitudinal stability against pitching is analyzed similarly. while a cargo ship may have a period of 13-15s. (MG) = (I/V) . A small GM means a small restoring torque. an early turret ironclad launced in 1869. The combination of a small GM and a small freeboard was originally considered desirable for a warship. but proved unsafe for Atlantic service. V (BoB) = V(0) + moment of the shaded volume . A ship with a large GM and a short roll period is called stiff. Therefore. however. had metacentric height of only 3 feet for stability. Longitudinal baffles reduce the effect (division into thirds reduces the effect by a factor of 9). if the hull has taken water. A passenger ship may have a roll period of 28s or so. Finally. Metacentric heights are typically 1 to 2 metres. Note that contributions from x>0 and x<0 are both positive. Therefore. The ship was eventually righted.can find the x-coordinate of B by taking moments of the volumes about the y-axis. when the ship heels this weight moves to the low side and counters the buoyancy that should give the ship stability. A ship with a small GM is said to be tender. Now. since it made a stable gun platform and presented a minimum area that had to be armoured. and so a long roll period. as they should be. a broadside ironclad launched in 1870. The free surface effect can greatly reduce the stability of a ship. incidentally. I. the ship tends to roll with a certain period. was such a ship. A list. The moment tending to restore the ship to upright is W times the righting arm GZ = MG x Δθ. Archimedes's Principle can also be applied to balloons. since it did not take water. ∫x 2dA is just the moment of inertia of the water-level area of the ship.moment of the equal compensating volume. and are absolutely necessary for ships like tankers. If dA is an element of area in the y=0 plane. with its cargo of Mazdas.(BoG). Therefore. HMS Sultan. (BoB)/Δθ = (MBo). which is desirable for passenger ships and for gun platforms (warships). is a permanent heel. and the moment is this times x. HMS Captain. imprudent shifting of ballast water caused MV Cougar Ace. Now.
At night. so it would rise 700-800 ft/min to an altitude of about 50. A 10g ceiling balloon was about 17" in diameter when inflated to have a free lift of 40g. Balloons are naturally stable. Submarines are yet another application of buoyancy. Of intermediate size was the pilot balloon. and only its unusual occurrence in natural gas from Kansas makes it available. since hydrogen is exceedingly flammable and explosive over a wide range of concentrations. like most large ones. so the balloon did not have to be followed optically. 3 ft in diameter before inflation. with hydrogen filling. which was easier to obtain and did not diffuse through the envelope quite as rapidly. Weather balloons had to be launched promptly after filling. and then with balloons filled with coal gas. It ascended 480ft the first minute. The balloon was inflated to give 800g free lift. and 360ft per minute afterwards. up to 2500ft. with their own characteristic problems.with a paper envelope ascended first in 1783 (the brothers got Pilâtre de Rozier and Chevalier d'Arlandes to go up in it). Small neoprene or natural rubber balloons have been used for meteorological observations. Such "fire balloons" were then replaced with hydrogen-filled balloons. helium is exceedingly rare.55 that of air. to find cloud ceilings by timing. Methane would be a good filler. However. 670ft in a minute and a half. can be contrasted with taut balloons with an elastic envelope.000 ft (15 km) before it burst. easily seen in binoculars. Large sounding balloons were used to lift a radiosonde and a parachute for its recovery. Slack balloons. Slack balloons will not be filled full on the ground. since the center of buoyancy is above the center of gravity in all practical balloons. but it also diffuses rapidly. a pilot balloon could carry a light for ceiling determinations. where air is 28. Helium is a little better in this respect. . and will plump up at altitude. An AN/AMT-2 radiosonde of the 1950's weighed 1500g. with a density 0. when it subtended about 2' of arc. This balloon was about 6 ft in diameter when inflated at the surface. the paper parachute 100g. or the desired free lift would not be obtained. which was followed with a theodolite to determine wind directions and speeds. The information was returned by radio telemetry. and the balloon 350g. Great care must be taken when filling balloons with hydrogen to avoid sparks and the accumulation of hydrogen in air. The lift obtained with helium is almost the same as with hydrogen (density 4 compared to 2. such as weather balloons. The greatest problem with using hydrogen for lift is that it diffuses rapidly through many substances.97). Helium has the great advantage that it is not inflammable.
Most hydrogen is made from the catalytic decomposition of hydrocarbons. For the energy content of a 13-gallon gasoline tank.0 g of water at 4°C. Both are rather expensive sources of hydrogen. Measurement of Specific Gravity The specific gravity of a material is the ratio of the mass (or weight) of a certain sample of it to the mass (or weight) of an equal volume of water. and all the hydrogen must be made with an input of energy usually greater than that available from the hydrogen. in casual speech the two are often confounded. since the weight of water is 62. however. or needed.The hydrogen for filling weather balloons came from compressed gas in cylinders. silicon or zinc could be used instead of aluminium. while specific gravity is a dimensionless ratio. it is clear that this difference is of no practical importance. and often with the appearance of carbon.5 lb/cuft. and in the second. and also by the confusion that gave us the distinction between cc and ml. a 600-gallon hydrogen tank would be required. since more energy is used than is recovered with the hydrogen. by definition. or CaH2 + 2H2O → Ca(OH) 2 + 2H2. density has the dimensions g/cc. which makes the specific gravity numerically equal to the density. Strictly speaking. the conventional reference material. any similar metal hydride. Electrolysis of water is an expensive source. but very convenient when only small amounts are required. or the reaction of hot coke with steam. so liquid storage is out of the question for general use. hydrogen compressed to 1000 psi requires 140 times as much volume for the same weight as gasoline.0 g of water at 4°C is 0. the density of water is 1 g/cc. The milliliter is the volume of 1. In the metric system.999973 cm 3 by measurement. The critical temperature of hydrogen is 32K. perhaps in lb/cuft or pcf. to more than three significant figures. However. Since most densities are not known. density. from the reaction of granulated aluminium with sodium hydroxide and water. The chemical reactions are 2Al + 2NaOH + 2H 2O → 2NaAlO2 + 3H2. Although about 60. Any enthusiasm for a "hydrogen economy" should be tempered by the fact that there are no hydrogen wells. The actual volume of 1.000 Btu/lb from gasoline. and the ml can be taken equal . or from the reaction of calcium hydroxide with water. Things are complicated by the variation of the density of water with temperature. In the first. is numerically different from the specific gravity.000 Btu/lb is available from hydrogen. In English units. compared to 20.
and then immersed in water.99987 g/ml. and from them the specific gravity of the powder. The weight of the powder and the weight of the displaced water can be determined. A sample in the form of a powder." If the flask is weighed empty. This can be carried out with an ordinary balance. have been created specifically for this application. the spheres that float are an indication of the temperature of the liquid. Since the density of a liquid decreases as the temperature increases. A pycnometer is a flask with a close-fitting ground glass stopper with a fine hole through it. Adding an extra weight to the sample allows measurement of specific gravities less than 1. but special balances. while a lower specific gravity will cause the hydrometer to float lower. and at 100°C 0.5461 at 20°C. full of water.W'). The small cross-sectional area of the stem makes the instrument very sensitive. Then the specific gravity is W/(W . the graduations ("degrees") are arbitrary and reference is made to a table to determine the specific gravities. The basic idea in finding specific gravity is to weigh a sample in air. it must be calibrated against standards. A higher specific gravity will result in a greater length of the stem above the surface. and W' the weight immersed. The closest spheres that will just float and just sink put limits on the specific gravity of the liquid. The name comes from the Greek puknos. can be put into the pycnometer. Galileo's thermometer worked this way. and 13. if W is the weight in air. such as the Jolly balance.99823. hollow spheres that will just float in certain specific gravities. which consists of a weighted float and a calibrated stem that protrudes from the liquid when the float is entirely immersed. at 20° 0. the specific gravity of the liquid can easily be calculated. a word meaning "density.to the cc. The denominator is just the buoyant force.95838. Mercury. The temperature dependence of the density may have to be taken into consideration in accurate work. A better instrument is the hydrometer. the weight of a volume of water equal to the volume of the sample. Of course. has a density 13. In most cases. This method was once used in Scotland to determine the amount of alcohol in distilled liquors. while we are at it.5955 at 0°C. . The density of water at 0°C is 0. The specific gravity of a liquid can be found with a collection of small weighted. so a given volume can be accurately obtained. and full of a liquid whose specific gravity is desired. to which the usual method of weighing cannot be used.
motor. and engine.they are also used by NASA in space missions. This means that syringes are the most basic form of hydraulics. It consists of two pistons and an oil-filled pipe connecting them. joined by joints. They handle tasks that are difficult or dangerous to human beings by transporting objects from one place to another. It requires IMO pumps which supply hydraulic power to the system and are driven by electric motors. as well as the alcohol content of whiskey. flow control valves. A hydraulic robotic arm works with the use of a computer. Robot arms are useful in many occupations.The robot also uses motion sensors to make sure it moves just the right amount.The size and speed of the pump determines the flow rate. Components often found in a hydraulic robot arm include seven metal segments. syringes just move the liquid. repetitive manufacturing work. A hydraulic robotic arm is an arm that requires a hydraulic system in order to operate. The load of the motor determines the pressure it gives off. OPERATION . which controls the robot by rotating individual step motors connected to each joint. two robotic arms are developed and studied. The syringes are used to pump fluids through the tube which will control the robot. as they operate by moving a liquid from one place to another. and the concentration of antifreeze compounds in engine coolants. Hydraulic systems also require pressure control valves. as well as a pump. Afterwards the most effective robot arm is then utilized to create a robot arm network testbed. including medical field to deliver medication to patients or perform procedures. Step motors move accordingly and precise.To implement a robotic arm. The difference is that a hydraulic system uses the liquid to move another object. A Hydraulic system is a power transmission system that uses the force of flowing liquids to transmit power. A hydraulic robotic arm is often used for heavy.Hydrometers are used to determine the specific gravity of lead-acid battery electrolyte. which allow on-way flow and direction control valves. CHAPTER 4 Methodology Syringes are essentially simple hydraulic systems.
during extension stroke. in which a piston connected to a piston rod moves back and forth. trunnions. The piston divides the inside of the cylinder into two chambers.Hydraulic cylinders get their power from pressurized hydraulic fluid. Ap is the piston face area and Ar is the rod cross-section area. the bottom chamber (cap end) and the piston rod side chamber (rod end / head end). This force and motion maybe in the form of . F p is the pulling force. The hydraulic cylinder consists of a cylinder barrel. to move the piston. which is typically oil.piston rod area): where P is the fluid pressure. and application of smooth. The piston has sliding rings and seals. clevises. A hydraulic cylinder is the actuator or "motor" side of this system. The barrel is closed on one end by the cylinder bottom (also called the cap) and the other end by the cylinder head (also called the gland) where the piston rod comes out of the cylinder. If we assume that the oil enters from cap end. effective power of pumped or compressed fluids (either liquids or gases) when this power is used to provide force and motion to mechanisms. The piston rod also has mounting attachments to connect the cylinder to the object or machine component that it is pushing / pulling. control. the fluid pressure in the rod end is (Pull Force) / (piston area . Lugs are common cylinder mounting options. if oil is pumped into the head (or gland) at the rod end and the oil from the cap end flows back to the reservoir without pressure. and the oil pressure in the rod end / head end is approximately zero. the force F on the piston rod equals the pressure P in the cylinder times the piston area A: During the retraction stroke. The piston pushes the oil in the other chamber back to the reservoir. The "generator" side of the hydraulic system is the hydraulic pump which brings in a fixed or regulated flow of oil to the hydraulic cylinder. Flanges. Introduction to Fluid power Fluid power is a term which was created to include the generation.
more reliable . wind. As used in this manual. and pneumatics. Consequently. which involves gases. regulating. Fluid power includes hydraulics. pneumatics is the portion of fluid power in which compressed air. and explores ways to take advantage of these properties. is used to transmit and control power to actuating mechanisms. It discusses the characteristics of gases and compares them with those of liquids. Use has broadened its meaning to include the behaviour of all liquids. and safety precautions associated with compressed gases Future Enhancements and Scope The system that we have built is a working prototype of a robot. It also explains factors which affect the properties of gases. Hence the future enhancements may include a much smaller. But it can still perform some level of object manipulation. It can be used to design such a robot. emphasis is placed primarily on the theory of operation of typical fluid power systems and components that have applications in naval equipment. and identifies gases commonly used in pneumatics and their pressure ranges. Pneumatics The word pneumatics is a derivative of the Greek word pneumatic. Hydraulics includes the manner in which liquids act in tanks and pipes. This manual presents many of the fundamental concepts in the fields of hydraulics and pneumatics. It can be defined as that branch of engineering science that pertains to gaseous pressure and flow. Individual training manuals for each rate provide information concerning the application of fluid power to specific equipment for which the rating is responsible. which involves liquids. Many applications of fluid power are presented in this manual to illustrate the functions and operation of different systems and components. However. It is only being developed to ensure that the design is feasible. It also discusses hazards of pneumatic gases. faster. fast and accurate in its movements. This prototype may not have the features and reliability of the original design.pushing. or breath. identifies and explains the gas laws. The differences are pointed out in the appropriate areas of this manual. fast and accurate. Hydraulics The word hydraulics is based on the Greek word for water. methods of controlling contamination. made by professional companies is not very efficient. deals with their properties. rotating. The gripper as compared to the ones. Liquids and gases are similar in many respects. which means air. not impractical and can be implemented on a much larger scale in a more efficient way. which should be compact. This chapter discusses the origin of pneumatics. although it is primarily concerned with the motion of liquids. pulling. It is intended as a basic reference for all personnel of the Navy whose duties and responsibilities require them to have a knowledge of the fundamentals of fluid power. and originally covered the study of the physical behaviour of water at rest and in motion. these are only representative of the many applications of fluid power in naval equipment. which can be small in size. or driving. or other gas.
Quick Movement Being a industrial robot. Active Accommodation Integration of sensors. in the aftermath of an earth quake. door opening and edge tracing. or Get the correct answer. and the minimum error that must be tolerated to operate the arm under closed servoloop operation. there are other . repeatability is the ability to duplicate an action or a result every time. precision refers to the degree of preciseness of a measurement. Accuracy The degree to which actual position corresponds to desired or commanded position. and robot motion to achieve alteration of a robot's preprogrammed motions in response to sensed forces. the degree of freedom from error. Compact Design A compact design results in a much faster motion and thus increases the accuracy and efficiency. FUNCTIONS AND PROPERTIES The primary function of a hydraulic fluid is to convey power. For example. Hence a compact robot will easily do the job. Used to stop a robot when forces reach set levels. Accuracy is frequently confused with precision. it requires very fast movement. It may have the ability to handle a much wider range of objects and the ability to maneuver them to much safer places. This is required as the industries have very little time for manufacturing of products.machine. Therefore a fast robot is necessary to be successfully used to improve production rate. Some of these enhancements are described below. It has to enter holes where humans cannot enter. the inaccuracies or imprecision of the mechanical linkages and gears and beam deflections under different load conditions. or to perform force feedback tasks like insertions. or reach the point in space. control. the robot has to search for people trapped under the rubble. In use. Accuracy refers to the degree of closeness to a "correct" value. Accuracy of a robot is determined by three elements of the system: the resolution of the control system. Accuracy involves the capability to hit a mark. Compact design is also required where the situation demands the robot to reach for small places. however. Therefore the robot can be enhanced to be of much smaller size for the purpose of a faster and accurate operation.
The table below lists the major functions of a hydraulic fluid and the properties of a fluid that affect its ability to perform that function:[2] Function Property • • Low compressibility (high bulk modulus) Fast air release Low foaming tendency Low volatility Good thermal capacity and conductivity Adequate viscosity and viscosity index Shear stability Viscosity for film maintenance Low temperature fluidity Thermal and oxidative stability Hydrolytic stability / water tolerance Cleanliness and filterability Demulsibility Antiwear characteristics Corrosion control Proper viscosity to minimize internal leakage High viscosity index Fire resistance Medium for power transfer and control • • Medium for heat transfer Sealing Medium • • • • • • • • • • • Lubricant Pump efficiency Special function • • • .important functions of hydraulic fluid such as protection of the hydraulic machine components.
but you also learned the importance of shop safety and working together with your team mates. Although the hydraulic technology is old. Accountants were in charge of your business expenses. Hopefully you were able to see how there is more to just having the best design.• • Friction modifications Radiation resistance Low toxicity when new or decomposed Biodegradability Material compatibility Environmental impact Functioning life • • • CONCLUTION I hope that you enjoyed this robotic arm unit. it remains a dominant system in modern industrial manufacturing process. Not only did you apply math and science to your project. Part of its popularity is that no other system has been found to be as efficient and effective in transferring energy through small tubes or hoses and other hard-to-reach parts. Engineers were in charges of the final design and oversight of building your robot arm. REFRENCE . Each team mate had a job to do. Finally Project Directors were in charge of your teams' public affairs and overall completion of your project. Working together as a team is just as important in accomplishing the different challenges you may face in your life. I hope that you will be able to apply the methods and ideas fromHydraulic systems have gained wide scale use and applicability in technologically driven industrial manufacturing process. The hydraulic system could by adapted for use from small industries to heavy manufacturing.
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Do you own Chedd's Gourmet Grilled Cheese? Contact us to connect with your diners.
Chedd's is no ordinary Grilled Cheese Sandwich. They have 35 different Wisconsin Cheese's that you can choose from, and a variety of breads, veggies, condiments and meats to create your own special Grilled Cheese Sandwich, or you can choose from over 25 Specialty Grilled Cheese Melts. Chedd's has been open for over 4 years, has been recognized in every major publication in Colorado, and and you...
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Eclectic deli highlights Wisconsin-cheese sandwiches and soups; build your own sandwich from 35 cheese, eight meat and 12 bread choices.
I just don't think the pizza is very good here. It's not disgusting or inedible but it's just not worth the time when there are so many other pizza places...
We really loved this place! We ordered a simple cheese and pepperoni and it was so delicious! There was zero shortage of of cheese or pepperoni on the pizza! The sauce had a little spice that was perfect! Wish we would have taken a picture but we were starving. And guess what?!? There was none left! Also, as it turns out, one of the owners is a super nice guy! We recommend this place!
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Mike (AKA) Walter got the pizza bug years ago when he worked at a neighborhood pizza place in Colorado Springs. He loved how everyone in the neighborhood kept coming by and how important it was to so many to have a great pizza place near where they lived. He also loved how much fun it was to hang out, listening to music and making great food that made people happy. After years of working in the...
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Stakes-placed America's Storm, a $3.6 million Keeneland September yearling, will enter stud at Joan Rogers' Applebite Farm near French Camp, Calif., for a fee of $4,000. Five-year-old America's Storm was twice stakes-placed and retired with three wins from 17 starts and earnings of $106,230. His first two dams, Lilly Capote (by Capote) and London Lil are both graded stakes winners.
Storm Cat's Son America's Storm to Applebite in California
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Anti-Nowhere League The Perfect Crime
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Tags » Podrick Payne
Game of Thrones: Brienne and the Blackfish
Game of Thrones Season 6 Episode 08 No OneBrienne attempts to negotiate with the Blackfish, but he refuses to abandon Riverrun, despite being sympathetic to Sansa's plight. 257 more words
Game of Thrones: Brienne and Podrick arrive at Riverrun
Game of Thrones Season 6 Episode 08 No OneBrienne and Podrick arrive at Riverrun, where they reunite with Jaime and Bronn.
PODRICK: Looks like a siege, my lady. 144 more words
Game of Thrones: Sansa accepts Brienne's vow of loyalty
Game of Thrones Season 6 Episode 01 The Red WomanAfter defeat the Bolton soldiers who persecuted Sansa and Theon, Brienne again offers to pledge her loyalty to Sansa, who finally accepts. 91 more words
Game of Thrones: Brienne's perfect sense of timing
Game of Thrones Season 6 Episode 01 The Red WomanSansa and Theon flee through the nearby forests. Upon being cornered by a squad of Bolton soldiers, they are rescued by Brienne and Podrick, who attack and kill the soldiers. 10 more words
I'd much rather talk about Team Sansa, though.
Okay! Since I'm still awake, let's see how much more I can say about Season 6 before I fall over!
There were some cliffhangers last season, yes? 337 more words
Have I embarrassed myself? Will I die on this hill?
In case anyone's seen the latest interview with Daniel Portman aka Podrick Payne, and wondering how I feel about his answers: I've seen it. I have ideas. 187 more words


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1. Mojo is a Grape Ninja!
"Alouatta staff feed baby monkeys grapes (their favorite thing on the planet!) They cannot eat too many grapes because it is like monkey candy."
This post was created by a member of BuzzFeed Community, where anyone can post awesome lists and creations. Learn more or post your buzz!
- Hillary Clinton has picked Virginia Sen. Tim Kaine as her running mate. He was considered a favorite for the ticket.
- At least 10 people, including the gunman, are dead after a shooting at a mall in Munich, Germany.
- ISIS has claimed responsibility for a bombing Saturday that killed at least 80 people in Afghanistan.


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Crazy Substitute Teachers
Enjoy, NG4.04 / 5.00 1,843 Views
Vacuum Salesman
This dude and his Megazord vacuum cleaner4.00 / 5.00 2,523 Views
Markiplier Animated | Mark Of The Survey Corps
This took far too long to make...3.89 / 5.00 4,748 Views
Not the skeleton, the girls playing with the plushee of the evil demon.
Don't understand what the skeleton was for. Mabey you would be so kind as to explain that to me. Otherwise it was good.
loved it
man i loved that one i even like how you made cutethulhu look like the real cthulhu from lovecrafts writings. i am very impressed i also like the end where lovecraft is smashing his head into his casket funny funny stuff. keep up the good work if you want to contact me its firstname.lastname@example.com
An H.P. Lovecraft parody! Words cannot describe how awsome that was!
And this opinioin Isn't just because I. in fact, own a cthulhu plushie
My 30 yo brother didn't get it xD


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Poker Tweets - Marcin Horecki
Red Rock Canyon with the oldschool bike? Why not! #OnMyBike pic.twitter.com/SeREUYq8Ts
Caught the Rio aircon flu. Taking a day off. #WSOP
Just realised I busted @catehall in the Monster Stack deep ITM. Shame the Dragon took those chips away from me. GG @catehall #Aontheriver
Out in 3b pot 37BB effective BU vs CO KK<33 on T32r vs very good reg. Open 2,5BB, 3b 6,75BB. He calls and CR flop. Not sure about my play.
Somehow got up to almost 800k at 8/16/2k at the beinning of WSOP day 3 Monster Stack. 1,5av and 200 players to beat. pic.twitter.com/tD2yxggPnT
Okay after 3BBs on the buble somehow made day 3 of Monster Stack with 19BBs (302k). ~270 players left. pic.twitter.com/VE9tseGsI0
Actually made the money with 3BBs (half of Monster start stack). Now sitting on 14BBs on the dinner break and just folded top pair vs set
Made the money of my 1st WSOP 2016 event Monster Stack with not so monster stack of 6BBs! Spin up time!


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Super Nation Games, submitted by Drew Curtis' FARK Drew Curtis' sidebar ad. When I first saw this site I laughed for nearly five minutes at the opening photograph. Then I tried to figure out what exactly "in the fuck" this site is about. I initially mistook it for some sort of shitty online game about being a super hero but after I read the review I realized it's just a big (and very retarded) story about some fictional Olympic-style game with attitude. You have to sign up to read anything other than the prologue.
Q. What is Super Nation?
A. Super Nation is a story about the Super Nation Games that take place on Earth in the year 2228 A.D.
Q. Is it like the Olympics?
A. Super Nation is what the Olympics would be if it were full of the kind of attitude you see in pro wrestling and if it were in a futuristic setting with lots of cool graphics and technology, robots and gadgets.
I sure wish the Olympics had wrestling attitude and "cool graphics"!!! I would love to see a figure skater talking trash about her opponent! It would be totally radical if a curling team was losing a match and then another curling team they were friends with came out and jumped into the match and helped them! Then there could be a bunch of cool graphics like the Olympic logo desolving into a robot that flies around and then that could morph into a pool of liquid metal!
I was betrayed by the bernio bros, the cougars, and this guy from back page I hired to keep me from jumping out a window at the DNC.
TOTAL WRECK - crazy-eyed hound is covered in cobwebs, has a vespiary on back, graffiti on side and savage thirst for boat fuel. Frankly, I'm in over my head. He's in room 115 at Motel 6, yours free. 555-2851
A dubious allegorical romp through a Fahey-filled world of Christly hackers and eyeliner tattoo!
Hillary Clinton has a new book! Here are some photo-shops of her, for you to enjoy.
Thirty games and a novel piece of hardware for sixty dollars? This is an insult to my honor.
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