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

Options

A. Increase by a factor of 4
B. Decrease by a factor of 2
C. Remain constant
D. Increase by a factor of 2

Answer

A

Explanation

`(k_(1))/(k_(2))=(L^(2))/(2I_(1))xx(2I_(2))/(L^(2))`
`(m(r//2)^(2))/(m(r)^(2))impliesk-(2)=4k_(1)`