Question

A wheel whose moment of inertia is $0.03kg{m}^2$ is accelerated from rest to $20rad/s$ in $5s.$ When the external torque is removed, the wheel stops in $1$ min. Find the frictional torque (in $Nm$)

Answer 1

Angular impulse $=$ change in angular momentum
$\therefore {\tau }_{f}t=I\omega$
or ${\tau }_f=\frac{I\omega }{t}=\frac{0.03\times 20}{60}=0.01N.m$