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Work

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-74

2025-11-03

497

Whenever a force acts upon a body in such a way as to move it, or to modify its motion, work is said to be done. However great the force used, no work is done unless the body is moved. A man going upstairs, a boy playing ball, and a crane lifting loads from one position to another (Fig. 1), are all doing work.

FIG. 1. - Loading of a Railroad Car on a Ship

 This picture, made in Seattle, shows a railroad car being put on board for shipment to Alaska. By means of the crane it was lifted off its tracks, at the left, and is now being swung into position over the ship.