Physics - Rotation Question with Solution | TestHub

Initial angular velocity ${\omega }_0=\frac{300\times 2\pi }{60}=10\pi$ rad/s.

Final angular velocity $\omega =-10\pi$ rad/s.

Time $t=50$ s.

Angular acceleration $\alpha =\frac{\omega -{\omega }_0}{t}=\frac{-10\pi -10\pi }{50}=-0.4\pi$ rad/s${}^2$.

Moment of inertia of the disc $I=\frac{1}{2}M{R}^2=\frac{1}{2}\times 100\times (1{)}^2=50$ kg m${}^2$.

Magnitude of torque $\tau =|I\alpha |=50\times 0.4\pi =20\pi$ Nm.

Answer: $20\pi Nm$