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Dec10-12, 05:34 PM
P: 34
Newton's first law states that unless an unbalanced force acts upon a body of matter, causing the mass to accelerate, the mass will stay at rest or travel indefinitely in a straight line with a constant velocity. Pendulums oscillate because gravity and the tension in the pendulum string/cable/ whatever are continuously acting upon the mass. Gravity still exists even in a vacuum. Even out in isolated space where gravity is less intrusive, if the pendulum were still magically swinging back and forth because of the presence of a magical force, the conservation of energy implies that some source of energy is being translated into the physical movement of the pendulum and that all of the energy will eventually become unusable heat.