SAT Subject Physics Practice Question 347: Answer and Explanation

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Question: 347

43. Two disks of equal mass but different diameter are connected with an axle system that allows them to roll down an incline together. Both disks start and finish at the same time.Which of the following statements best describes the disks?

A. Their tangential velocity is the same.
B. Their tangential acceleration is the same.
C. Their angular velocity is the same.
D. Their angular displacement is the same.
E. Their angular acceleration is the same.

Correct Answer: A


The correct answer is (A). Both disks move the same linear distance in the same time period. The smaller disk must make more revolutions to have the same tangential velocity as the large wheel. Since the number of revolutions for the small disk is larger, it also has a large angular acceleration.

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