A child is standing with folded hands at the centre ofplatform 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 becomes doubled. The kinetic energy of the system now is

A child is standing with folded hands at the centre ofplatform rotatin

1.	A child is standing with folded hands at the centre ofplatform 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 becomes doubled. The kinetic energy of the system now is
Answer» 2 K `(K)/(2)` `(K)/(4)` 4 K Solution :According to the principle of conservation of angular momentum , `I OMEGA `= constant As I is doubled , `omega` BECOMES half Now KE of ROTATION , `K = (1)/(2) I omega^(2)` SINCE I is doulbed and `omega` is halved , KE will become half i.e., `(K)/(2)`