Question

A metal sphere of radius R and specific heat S is rotating about an Axis passing through its centre at a speed of n rotations per second . it is suddenly stopped and 50% of its energy is used to increasing its temperature then the rise in temperature of the sphere is

Answer 1

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A.T.Q 
It's rotational K.E. = n*m*(r^2)*pi / 5
So 50% energy = n*m*(r^2)*pi / 10
So that much energy is absorbed by sphere to increase it's temperature:
So
m*S*(del. T) = n*m*(r^2)*pi / 10
So del. T = n * r^2 *pi / (10*S)

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