One end of a 1.0 m string is fixed, the other end is attached to a 2.0 kg stone. The stone swings in a vertical circle, passing the top point at 4.0m/s. The tension force of the string (in newtons) at this point is about:
Correct answer: A. 0
- A. 0
- B. 20
- C. 12
- D. 32
Explanation
At the top of the swing, the stone experiences two forces: the tension in the string and gravity. For the stone to maintain circular motion, the centripetal force must be provided by the net force acting downward. At the top point, the gravitational force (mg) is sufficient to provide the necessary centripetal force, meaning the tension is zero. Therefore, the correct answer is Option A: 0.Option B suggests the tension equals the weight, which would be true if additional centripetal force was needed beyond gravity. Option C results from a calculation error, possibly involving incorrect dynamics. Option D implies a misunderstanding of the forces involved, suggesting excessive tension beyond what is required.
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