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تسجيل

Motion of a Pendulum

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  P- 90

2025-11-05

685

Whenever a pendulum, as OA (Fig. 1), is moved out of its position of rest to any other position, as OB, it will, on being released, go back to A and, owing to the kinetic energy developed by its fall, go on to the position C, АС being slightly less than AB. A to-and-fro movement once over its path and back is called an oscillation, or vibration; and the distance that A moves from its position of rest-АВ or AC -is the amplitude of the oscillation. In order to find the force that causes the pendulum to move over this path, we must find two components of the force of gravity BD, one, BE, which produces a pressure on the point of suspension O, without producing any motion, and the other, BF, which acts at a right angle to BE and is the force required. The magnitude of this force is that fraction of the weight of the pendulum represented by    This force varies from zero at A to the weight of the pendulum at a point on a level with O. Since in ordinary pendulums the amplitude is never large, the moving force is always a small part of this weight.

FIG.1