A child is standing with folded hands at the centre of the platform rotating about its central axis. The kinetic energy of the system is ' K '. The child now stretches his arms so that the m

Question

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

TestHub · Accepted Answer

K I ′ ​ = 2 1 ​ I ω 2 = 2 I ​ By law of conservation of angular momentum ​ I ′ ω ′ = I ω ∴ 2 I ω ′ = I ω ∴ ω ′ = 2 ω ​ K ′ = 2 1 ​ I ′ ω ′2 = 2 1 ​ ( 2 I ) ( 2 ω ​ ) 2 = 2 1 ​ ( 2 1 ​ I ω 2 ) = 2 K ​ ​

Physics - Rotation Question with Solution | TestHub

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