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AP® Physics C: Mechanics

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Moderate

Vertical Circle: Top and Bottom Tension

APPHMC-KSOBSK

A ball of mass $m$ is moved in a vertical circle of radius $r$ as shown in the figure below. The tension in the string is varied so that it always keeps the ball moving in a perfect circle as the ball changes speed, because it is rising and falling in the Earth's gravitational field.​

John Krehbiel. Created for Albert.io. Copyright 2016. All rights reserved.

What is the difference in the tension in the string at the bottom of the circle vs. the top?

A

$2mgr$

B

$4mgr$

C

$2mg$

D

$4mg$

E

$6mg$