Rotational kinetic energy of a solid cylinder

Practice question

Question

A solid cylinder of mass 4kg and radius 0.3m rotates about its axis at 6rad/s. What is its rotational kinetic energy?

Options

Choose one · Correct answer highlighted

3.0 J 3.24 J Correct 3.5 J 4.0 J

Explanation

I = 12MR2 = 12×4×(0.3)2 = 0.18kg m2. K = 12Iω2 = 12×0.18×(6)2 = 0.09×36 = 3.24J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 3.24 J. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

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