The work done by the centripetal force on a body moving in a circle at constant speed is
Correct answer: B. zero
- A. maximum
- B. zero
- C. equal to the kinetic energy
- D. negative
Explanation
The force points to the centre while the displacement is along the tangent, so the two are perpendicular and the dot product is zero at every instant. This is consistent with the speed and therefore the kinetic energy staying constant. A force can change the direction of motion without doing any work at all.
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About Work
Work is done when a force produces displacement, with its value determined by the component of force along the displacement. The topic covers positive, negative and zero work, work by variable forces from force-displacement graphs, and the connection between net work and change in kinetic energy.
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