Physics Two Dimensional Motion Question 111

Question: A body of mass 0.4 kg is whirled in a vertical circle making 2 rev/sec.If the radius of the circle is 2 m, then tension in the string when the body is at the top of the circle, is

[CBSE PMT 1999]

Options:

A) 41.56 N B)89.86 N C) 109.86 N D)115.86 N

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Answer:

Correct Answer: D

Solution:

Tension at the top of the circle,$ T=m{{\omega }^{2}}r-mg $

$ T=0.4\times 4{{\pi }^{2}}n^{2}\times 2-0.4\times 9.8=115.86,N $