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Potential Energy

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  P-70

2025-11-03

542

We have only to loosen the catch which holds the head in place to find that the head also is ready to do work. When the catch is loosened, the head falls, strikes upon the top of the pile, and its capacity for doing work is shown by driving the pile into the ground. If the head is again raised, but only half as high, it will be found on dropping it that but half as much work is done. This shows that the height from which the head falls must be taken into account, as well as the weight of the head itself. The energy that a body has on account of its position is called potential energy. The work that has been done on a body to place it in a certain position is the measure of its potential energy. This measure is expressed by the equation

P.E. = Wh,

in which W is the weight of the body and h is its vertical height above the point with reference to which its potential energy is measured. Energy is measured in the same units as work. For instance, the potential energy of a 10-lb. weight ready to fall 6 ft. is 60-foot pounds.