Kinetic energy of rotation is half the product of the moment of inertia (l) of the body and the square of the angular velocity (ω) of the body. Kinetic energy of rotation =
1
2
× moment of inertia × angular velocity i.e., K=
1
2
lω2 ω2=
2K
l
Given l=1.2kgm2,K=1500J ω2=
2×1500
1.2
⇒ω=50rad∕s From the equation of angular motion, we have ω=ωn+αt where ω0 is initial angular velocity, α is angular acceleration and t is time given ω0=0 ω=50 rad/s, α=25 rad/s2 t=