AP Physics 1 Question 64: Answer and Explanation

Test Information

Use your browser's back button to return to your test results.

Question: 64

4.

The diagram above shows a top view of an object of mass m on a circular platform of mass 2m that is rotating counterclockwise. Assume the platform rotates without friction. Which of the following best describes an action by the object that will increase the angular speed of the entire system?

  • A. The object moves toward the center of the platform, increasing the total angular momentum of the system.
  • B. The object moves toward the center of the platform, decreasing the rotational inertia of the system.
  • C. The object moves away from the center of the platform, increasing the total angular momentum of the system.
  • D. The object moves away from the center of the platform, decreasing the rotational inertia of the system.

Correct Answer: B

Explanation:

B The only true statement in regards to rotational motion is (B). A mass that has greater inertia is harder to rotate. The further away the mass is from the axis of rotation, the greater the rotational inertia will be. So, when the object moves toward the center of rotation, rotational inertia is
decreased.