Question

A ball is tethered to a pole by a rope. The ball is set spinning around the pole with the tension in the rope providing a centripetal force. As the ball spins around the pole, the rope winds around the pole, getting shorter with each cycle. Ignoring air resistance and friction, the tangential speed of the ball will

Group of answer choices

stay constant.

decrease.

increase.

Answer 1

there is only one force acting on ball which is tension force in string(gravity is not considered here as we are considering only motion in horizontal plane).

now as rope winds around pole, its radius decreases but tension force still remains in parallel to rope so tangential speed is still perpendicular to tension force so tension can only change its direction but not change the tangential speed.

so tangential speed stay constant.

note that speed along the rope i.e. radial speed does change so overall speed increases