By definition, the moment of inertia of the body with the radius of gyration Rg=40cm and mass m=6kg will be:
I=mRg2=6⋅0.42=0.96kg⋅m2
The rotational KE:
Erot=21Iω2 where ω is the angular velocity. If the frequency of rotation is ν=300rpm=5Hz, then the angular velocity will be:
ω=2πν=2π⋅5≈31.4rad/s Thus, the rotational KE will be:
Erot=21⋅0.96⋅31.42=473.7J
Answer. I = 0.96 kg*m^2, Erot = 473.7 J.
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