Question

11. A solid bowling ball rolls down a ramp. Which of the following forces exerts a torque on the bowling ball about its center?

(a) the weight of the ball.
(b) the normal force exerted by the ramp.
(e) the friction force exerted by the ramp.
(d) more than one of the above.
(e) depends on whether the ball rolls without slipping.

Answer 1

c. friction force exerted by the ramp

Step-by-step explanation:

torque = force * lever arm

the weight (gravity) acts about the center of the bowling ball, so the lever arm is 0 and the torque from gravity is also 0.

the normal force acts perpendicular to the ramp and through the center of the bowling ball, so the lever arm and torque are also 0.

the friction force doesn't act through the center, instead acting parallel to the direction of motion, so the lever arm isn't 0.

so friction is the only force with a torque on the bowling ball about the center.

note: if you were to take the point of contact between the bowling ball and the ramp as the pivot point, the answer would be different. be aware of what pivot point the question is using ^^