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A body of mass 0.4 kg is whirled in a vertical circle making 2 rev/sec. If the radius of the circle is 1.2 m, then tension in the string when the body is at the top of the circle, is
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- 41.56 N
- 89.86 N
- 109.86 N
- 115.86 N
Correct Option: A
Given : Mass (m) = 0.4 kg
Its frequency (n) = 2 rev/sec
Radius (r) = 1.2 m. We know that linear velocity of the body (v) = ωr = (2πn)r
= 2 × 3.14 × 1.2 × 2 = 15.08 m/s.
Therefore, tension in the string when the body is at the top of the circle (T)
| = | - mg = | - (0.4 × 9.8) | ||
| r | 2 |
= 45.78 - 3.92 = 41.56 N
