Work
Work (physics), product of a force applied to a body and the displacement of the body in the direction of the applied force. While work is done on a body, there is a transfer of energy to the body, and so work can be said to be energy in transit. The units of work are identical to those of energy. If, for example, an object is lifted from the floor to the top of a table, work is done in overcoming the downward force of gravity, and the energy imparted to the body as work will increase its potential energy. Work is also expended when a force accelerates a body, such as the acceleration of an airplane because of the thrust forces developed by its jet engines. The force need not be simply a mechanical force (see Mechanics ) as in the case of lifting a body or accelerating a plane by jet reaction; it can also be an electrostatic, electrodynamic, or surface-tension force (see Electricity ; Surface Tension ). On the other hand, if a constantly acting force does not produce motion, no work ...