MCAT Physics Question 23: Answer and Explanation

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Question: 23

8. During uniform circular motion, which of the following relationships is necessarily true?

  • A. No work is done.
  • B. The centripetal force does work.
  • C. The velocity does work.
  • D. Potential energy depends on position of the object around the circle.

Correct Answer: A

Explanation:

In uniform circular motion, the displacement vector and force vector are always perpendicular; therefore, no work is done. Potential energy is constant for an object in uniform circular motion, whether it is the gravitational potential energy of a satellite orbiting the Earth or the electrical potential energy of an electron orbiting the nucleus of an atom. In both cases, potential energy does not change and does not depend on the position of the object around the circle, eliminating choice (D).

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