Question

If the kinetic energy of rotation of a body about an axis is $9J$ and the moment of inertia is $2kg{m}^2$, then the angular velocity of the body about the axis of rotation in $rad/s$ is

• A. $2$
• B. $3$
• C. $1$
• D. $9$

Answer 1

The correct option is B $3$

$\begin{array}{cc}\text{Kinetic Energy}K.E& =\frac{1}{2}I{\omega }^2\\ 9& =\frac{1}{2}\times 2\times {\omega }^2\\ \omega & =3\\ \text{Hence option}B\text{is correct}& \end{array}$