Uniform circular motion: A string is attached to the rear-view mirror of a car. A ball is hanging at the other end of the string. The car is driving around in a circle, at a constant speed. Which of the following lists gives all of the forces directly acting on the ball?
A) tension and gravity
B) tension
C) tension, gravity, and the centripetal force
D) tension, gravity, the centripetal force, and friction

Question

Quizplus · Accepted Answer

The forces directly acting on the ball are tension (from the string pulling the ball towards the center of the circle) and gravity (pulling the ball downwards). The centripetal force is not an additional force but is the net force towards the center of the circle, provided here by the tension in the string. Friction does not directly act on the ball in this scenario.

Uniform Circular Motion: a String Is Attached to the Rear-View