Rotational K.E = 0.5*I*w^2
I= moment of inertia
and w= angular speed
when I' = 5*I
and w' = w / 5
=> K.E ' = 0.5 *5*I*(w/5)^2
=> K.E ' = 0.2 * (0.5*I*w^2)
=> K.E ' = 0.2 K.E hence option (E) ans...
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