SAT Subject Physics Practice Question 352: Answer and Explanation

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Question: 352

48. The velocity of a moving object is doubled. Which of the following statements about the object is correct?

A. The kinetic energy of the object increases by four.
B. The displacement of the object increases by four.
C. The momentum of the object increases by four.
D. The frictional force increases by four.
E. None of these quantities increase by four.

Correct Answer: A


The correct answer is (A). The kinetic energy equation is KE = . mv2 . Every time the velocity of an object doubles, its energy increases by a factor of 4. The momentum is directly related to the velocity, so a doubling of an object's velocity doubles the momentum of the object. The frictional force is a constant force no matter what happens to the velocity.

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