Question

A body with moment of inertia $3Kg{m}^2$ is at rest. A torque of $6Nm$ applied on it rotates the body for $20$ seconds. The angular displacement of the body is

• A. 800 radians
• B. 600 radians
• C. 400 radians
• D. 200 radians

Answer 1

Answer: (C)

400 radians

We have $\tau =I\alpha$
or
$\alpha =\frac{6}{3}=2rad/s^2$
using $\theta ={\omega }_{0}t+\frac{1}{2}\alpha t^2$ we get
$\theta =0\left(20\right)+\frac{1}{2}2\left({20}^2\right)=400radians$