One end of a 1.0-m long string is fixed; the other end is attached to a 2.0-kg stone.The stone swings in a vertical circle, passing the bottom point at 4.0 m/s.The tension force of the string at this point is about:
A)0 N
B)12 N
C)20 N
D)32 N
E)52 N

Question

Quizplus · Accepted Answer

The tension at the bottom of the circle is the sum of the gravitational force and the centripetal force. The gravitational force is mg = 2.0 kg * 9.8 m/s² = 19.6 N. The centripetal force is mv²/r = 2.0 kg * (4.0 m/s)² / 1.0 m = 32 N. Therefore, the total tension is 19.6 N + 32 N ≈ 52 N.

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