A child is standing with folded hands at the center of a platform rotating about its central axis. The kinetic energy of the system is `K`. The child now stretches his arms so that the moment of inertia of the system doubles. The kinetic energy of the system now is: a) K/4 b) K/2 c) 2K d) 4K

Options

A. `2K`
B. `K/2`
C. `K/4`
D. `4K`

Answer

B

Explanation

`KE=(L^(2))/(2l) L` remains constant doubles so `KE` becomes half.