rotational speed is the meaning of torque in physics.
what is the meaning of torque in physics?
rotational speed
"torque" is defined mathematically as the rate of change of angular momentum of an object. the definition of torque states that one or both of the angular velocity or the moment of inertia of an object are changing. "moment" is the general term used for the tendency of one or more applied forces to rotate an object about an axis, but not necessarily to change the angular momentum of the object (the concept which is called "torque" in physics). for example, a rotational force applied to a shaft causing acceleration, such as a drill bit accelerating from rest, results in a moment called a "torque". by contrast, a lateral force on a beam produces a moment (called a bending moment), but since the angular momentum of the beam is not changing, this bending moment is not called a "torque". similarly with any force couple on an object that has no change to its angular momentum, such moment is also not called a "torque".
torque
as the output of an impact wrench, when hammering, is a very short impact force, the actual effective torque is difficult to measure, with several different ratings in use. as the tool delivers a fixed amount of energy with each blow, rather than a fixed torque, the actual output torque changes with the duration of the output pulse. if the output is springy or capable of absorbing energy, the impulse will simply be absorbed, and virtually no torque will ever be applied, and somewhat counter-intuitively, if the object is very springy, the wrench may actually turn backwards as the energy is delivered back to the anvil, while it is not connected to the hammer and able to spin freely. a wrench that is capable of freeing a rusted nut on a very large bolt may be incapable of turning a small screw mounted on a spring. "maximum torque" is the number most often given by manufacturers, which is the instantaneous peak torque delivered if the anvil is locked into a perfectly solid object. "working torque" is a more realistic number for continually driving a very stiff fastener. "nut-busting torque" is often quoted, with the usual definition being that the wrench can loosen a nut tightened with the specified amount of torque in some specified time period. accurately controlling the output torque of an impact wrench is very difficult, and even an experienced operator will have a hard time making sure a fastener is not under-tightened or over-tightened using an impact wrench. special socket extensions are available, which take advantage of the inability of an impact wrench to work against a spring, to precisely limit the output torque. designed with spring steel, they act as large torsion springs, flexing at their torque rating, and preventing any further torque from being applied to the fastener. some impact wrenches designed for product assembly have a built-in torque control system, such as a built-in torsion spring and a mechanism that shuts the tool down when the given torque is exceeded. when very precise torque is required, an impact wrench is only used to snug down the fastener, with a torque wrench used for the final tightening. due to the lack of standards when measuring the maximum torque, some manufacturers are believed to inflate their ratings, or to use measurements with little bearing on how the tool will perform in actual use. many air impact wrenches incorporate a flow regulator into their design, either as a separate control or part of the reversing valve, allowing torque to be roughly limited in one or both directions, while electric tools may use a variable speed trigger for the same effect.
impact wrench