Question

An angular impulse of $20Nms$ is applied to a hollow cylinder of mass $2kg$ and radius $2cm$. The change in its angular speed is

• A. $25rad/s$
• B. $2.5rad/s$
• C. $250rad/s$
• D. $25000rad/s$

Answer 1

The correct option is D $25000rad/s$

Given mass $m=2kg$ , radius $r=2cm=0.02m$ and angular impulse $L=20Nms$, Let angular speed is $\omega$.

Moment of Inertia of cylinder , $I=m{r}^2=2\times {0.02}^2=0.0008$

$\Rightarrow L=I\Delta \omega$ $\Rightarrow 20=0.0008\Delta \omega$

$\Rightarrow \Delta \omega =25000$ $rad/s$