AP Physics 1 Question 450: Answer and Explanation

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Question: 450

8. Which of the following objects has the greatest rotational inertia?

  • A. A 1 kg solid ball with radius of 5 cm
  • B. A 1 kg hollow ball with radius of 5 cm
  • C. A 5 kg solid ball with radius of 5 cm
  • D. A 5 kg hollow ball with radius 5 cm

Correct Answer: D

Explanation:

D

Rotational inertia is directly proportional to the mass of the object. Eliminate (A) and (B), as they have smaller masses. The farther away the mass is from the axis of rotation, the greater the rotational inertia. The mass of a hollow ball is farther away from the axis of rotation than that of a solid ball. Eliminate (C). Choice (D) is correct.