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A small mass attached to a string rotate...

A small mass attached to a string rotates on a frictionless table top as shown in Fig. If the tension in the string is increased by pulling the string causing the radius of the circular motion to decrease by a factor of 2, the kinetic energy of the mass will

A

Increase by a factor of 4

B

Decrease by a factor of 2

C

Remain constant

D

Increase by a factor of 2

Text Solution

Verified by Experts

The correct Answer is:
A
`(k_(1))/(k_(2))= (L^(2))/(2I_(1)) xx (2I_(2))/(L^(2))`
`= (m(r//2)^(2))/(m(r)^(2)) rArr k_(2)= 4k_(1)`
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