can the work by kinetic friction on an object be positive? zero? - introduction of work, energy and power
can the work by kinetic friction on an object be positive? zero?
yes. let us consider a block a which is resting on another block b. block b is resting on a smooth horizontal surface. let the coefficient of friction between the blocks be \[\mu\] . when a force f is applied on block b in the forward direction as shown in the above figure, block a moves with block b in the direction of the applied force. the frictional force on block a and the displacement will be in the forward direction. therefore, work done by the frictional force is positive. if we consider the reference frame of block b, then displacement of block a will be zero. therefore, work done by the frictional force is zero.
coefficient of friction is defined as the ratio of the force of friction acting between two objects and the force which is pushing them together. the value of the coefficient of friction varies from zero to one. there are two types of the coefficient of friction: static coefficient of friction kinetic (also known as sliding) coefficient of friction. therefore, the coefficient of friction depends on the nature of the surface. physics 101 notes: 8/25 (week 2 continued)  force o defined as a push or a pull, and is a vector quantity, meaning that it has direction depending on which way it is being pushed or pulled o it has amount and direction (how much force is being applied and in which direction it is moving)  newton’s first law o first draft: “an object that is free of forces move in a straight line and covers equal distances in equal time” o final: “an object that is free of external forces moves at a constant velocity”  how does a skater start, stop, or turn? o acceleration: “the rate at which an object’s velocity is changing with time o acceleration, s net work done in carrying charge along closed loop by electric field is zero. hence, the tangential component of the electric field is continuous from one side of a charged surface to the other. 1. according to kinetic theory of ideal gases, molecules of a gas are in incessant random motion, colliding against each other and with the walls of the container. all these collisions are perfectly elastic collision.2. in perfectly elastic collision, total kinetic energy of gas is conserved.3. here, we have a mixture of oxygen and hydrogen gas. thereforek.e of oxygen + k.e of hydrogen=constant4. so, if kinetic energy of oxygen molecules increases, then kinetic energy of hydrogen molecules decreases or vice-versa so that, sum of both kinetic energies remains constant.5. therefore, both option (c) and (d) are correct. the force on the wire due to the interaction of magnetic fields of the bar magnet and current carrying wire can act only in upwards or downwards direction. 1. introduction: rough surface in contact i. surface of engineering materials: generals  surfaces have chemical properties, which are different from bulk virgin material. o most metallic surfaces in air have oxide layers, which change the chemical and mechanical properties of the surfaces.  surfaces have mechanical properties, which are different from bulk material. o machining or sliding contact makes strain hardened (or work hardened) layer and highly deformed layer, whose strength are different from bulk.  real engineering surfaces are rough. mirror like smooth surface afm image hello,
  

  

these are the important parts in thermodynamics.
  

  

**laws of thermodynamics**
**conduction, convection, and radiation**
**kinetic theory of gases**
**thermal expansion**
**calorimetry**
  

  

i hope this helps. hi,
all physical changes are not
reversible cutting of tree is an irreversible physical change
all chemical changes are not
necessarily irreversible

the reaction between hydrogen and oxygen to form water is an
example reversible chemical reaction the reaction can be
represented as:
h2 + 1/2 o2→ h2o want, regard, praise, include, push, buy, warm, pay attention, let go, encourage, permit, admit, allow, support, flatter, compliment, accept, sanction, approve, release, socialize, respect, be friendly, use, heat, welcome, note. associative law of addition:
a + (b+c) = (a+b) + c

commutative law of addition:
a + b = b + a

additive inverse:
a + (-a) = 0

zero property:
a + 0 = a

subtraction is basically the same thing as addition.
a - b = a + (-b)
instead of subtracting b, you add its additive inverse.