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A circular solid disc of uniform thickness 20 mm, radius 200 mm and mass 20 kg, is used as a flywheel. If it rotates at 600 rpm, the kinetic energy of the flywheel, in Joules is

A circular solid disc of uniform thickness 20 mm, radius 200 mm and mass 20 kg, is used as a flywheel. If it rotates at 600 rpm, the kinetic energy of the flywheel, in Joules is Correct Answer 790

For flywheel K.E = 1/2Iω2 ω = 2πN/60 = 62.83 rad/s I (for solid circular disk) = 1/2mR2 = 0.4 kg m2 Hence, K.E = 790 Joules.

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