A disk is free to rotate on a fixed axis. A force of a given magnitude F, in the plane of the disk, is to be applied. Of the following alternatives the greatest angular acceleration is obtained if the force is:
Correct answer: B. applied tangentially at the rim
- A. applied tangentially halfway between the axis and the rim
- B. applied tangentially at the rim
- C. applied radially halfway between the axis and the rim
- D. applied radially at the rim
Explanation
τ = lα rF = lα α = rF/l Torque produces the angular acceleration in the body. The torque will be maximum if the force acts at a larger distance from the fixed axis. In the given case the greatest acceleration is obtained if the force is applied tangentially at the rim.
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About Simple Harmonic Motion
Simple harmonic motion is oscillation in which acceleration is directly proportional to displacement and directed toward the equilibrium position. Work includes displacement, velocity, acceleration, phase, period, frequency, amplitude and energy, with applications to springs and simple pendulums. The restoring force and the conditions for SHM distinguish it from general periodic motion.
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