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Work, in physics and mechanics, transfer of energy by a force acting to displace a body. Work is equal to the product of the force and the distance through which it produces movement. Although both force force, commonly, a "push" or "pull," more properly defined in physics as a quantity that changes the motion, size, or shape of a body. Force is a vector quantity, having both magnitude and direction.
Displacement are vector U [−3,1] and V [5,2], one can add their corresponding components to find the resultant vector R [2,3], or one can graph U and V on a set of coordinate axes and complete the parallelogram formed with U and V. quantities, having both magnitude and direction, work is a scalar quantity, having only magnitude. If the force acts in a direction other than that of the motion of the body, then only that component of the force in the direction of the motion produces work. Thus when a 5-lb (22.4-newton) force pulls a body 10 ft (3 m), it does 50 foot-pounds (67.2 meter-newtons) of work. If a force acts on a body constrained to remain stationary, no work is done by the force. Even if the body is in motion, the force must have a component in the direction of motion. Thus, any centripetal force, such as the sun's gravitational pull on the earth, does no work because it acts at right angles to the motion and has no component in that direction (see centripetal force and centrifugal force centripetal force and centrifugal force, action-reaction force pair associated with circular motion .
When there is no friction friction, resistance offered to the movement of one body past another body with which it is in contact. In certain situations friction is desired. Without friction the wheels of a locomotive could not "grip" the rails nor could power be transmitted by belts and a force acts on a body, the work done by the force is equal to the increase of the kinetic and potential energy of the body, since all the energy expended by the agency exerting the force must be gained by the body. If frictional forces are present, then some of the work must go to overcome friction and appears finally in the form of heat energy. A simple machine machine, arrangement of moving and stationary mechanical parts used to perform some useful work or to provide transportation. From a historical perspective, many of the first machines were the result of human efforts to improve war-making capabilities; the term
is a device for converting work into another form of energy. For example the jackscrew converts an input of work done on the machine to raise the load. The efficiency of a machine, which is defined as the ratio of the work output to the work input, is always less than one, since some of the input is invariably wasted in overcoming friction. The element of time does not enter into the computation of work; the time rate of doing work is called power power, in physics, time rate of doing work or of producing or expending energy