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A simple pendulum of length l is pulled to a maximum angular displacement θ. The greatest kinetic energy of its bob of mass m is
- 1/2 ml/g
- mg/2l
- mg l (1 - cos θ)
- mg l sin θ/2
Correct answer: mg l (1 - cos θ)
Solution
The greatest kinetic energy of the pendulum bob occurs at the lowest point of its swing, where all the potential energy converted from the height is transformed into kinetic energy. The potential energy at the maximum height is given by mg l (1 - cos θ), which equals the kinetic energy at the lowest point.
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