Connecting Linear and Rotational Motion AP Physics C Mechanics MCQ – Exam Style Questions etc.
Connecting Linear and Rotational Motion AP Physics C Mechanics MCQ
Unit 5: Torque and Rotational Dynamics
Weightage : 10-15%
Question
In trial 1 of an experiment, a cart moves with speed \(v_0\) on a frictionless, horizontal track and collides elastically with another cart that is initially at rest. In trial 2, the setup is identical except that the carts stick together during the collision. How does the speed of the two-cart system’s center of mass change, if at all, during the collision in each trial?
▶️Answer/Explanation
Ans:A
Question
The wheel on a vehicle has a rotational inertia of \(2.0 \mathrm{~kg} \cdot \mathrm{m}^2\). At the instant the wheel has a counterclockwise angular velocity of \(6.0 \mathrm{rad} / \mathrm{s}\), an average counterclockwise torque of \(5.0 \mathrm{~N} \cdot \mathrm{m}\) is applied, and continues for \(4.0 \mathrm{~s}\). What is the change in angular momentum of the wheel?
(A) \(12 \mathrm{~kg} \cdot \mathrm{m}^2 / \mathrm{s}\)
(B) \(16 \mathrm{~kg} \cdot \mathrm{m}^2 / \mathrm{s}\)
(C) \(20 \mathrm{~kg} \cdot \mathrm{m}^2 / \mathrm{s}\)
(D) \(32 \mathrm{~kg} \cdot \mathrm{m}^2 / \mathrm{s}\)
▶️Answer/Explanation
Ans:C
Question
A blue sphere and a red sphere with the same diameter are released from rest at the top of a ramp. The red sphere takes a longer time to reach the bottom of the ramp. The spheres are then rolled off a horizontal table at the same time with the same speed and fall freely to the floor. Which sphere reaches the floor first?
(A) The red sphere
(B) The blue sphere
(C) The sphere with the greater mass
(D) Neither; the spheres reach the floor at the same time.
▶️Answer/Explanation
Ans:C
Question
The diagram above shows a top view of a child of mass \(M\) on a circular platform of mass \(5 M\) that is rotating counterclockwise. Assume the platform rotates without friction. Which of the following describes an action by the child that will result in an increase in the total angular momentum of the child-platform system?
(A) The child moves toward the center of the platform.
(B) The child moves away from the center of the platform.
(C) The child moves along a circle concentric with the platform (dashed line shown) opposite the direction of the platform’s rotation.
(D) None of the actions described will change the total angular momentum of the childplatform system.
▶️Answer/Explanation
Ans:B