Question

Force of $10N$ is applied tangentially on a disc of mass $2kg$ and radius $1m$ , which is free to rotate on its geometric axis then angular velocity of disc after $2seconds$ is :-

• A. $10rads^{- 1}$
• B. $20rads^{- 1}$
• C. $5rads^{- 1}$
• D. $40rads^{- 1}$

Answer 1

Answer: (B)

For Disc $\tau=R\times F=I\alpha $
Here $\left(I = \frac{M R^{2}}{2}\right)$
$1\times 10=\frac{2 \times 1}{2}\times \alpha $
$\alpha =10rads^{- 2}$
then $\omega =\omega _{0}+\alpha t$
$=0+10\times 2$
$=20rads^{- 1}$