A child is standing with folded hands at the centre 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 inerti

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

TestHub · Accepted Answer

According to the principle of conservation of angular momentum, I ω = constant As I is doubled, ω becomes half Now K.E. of rotation, K = 2 1 ​ I ω 2 Since I is doubled and ω is halved, K.E. will become half i.e. 2 K ​ .

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