Question

A spherical solid ball of $1kg$ mass radius $3cm$ is rotating about an axis passing through the centre with an angular velocity of $50radian/s$. The kinetic energy of rotation is:

• A. $4500$
• B. $90$
• C. $\frac{9}{20}$
• D. $\frac{9}{10}$

Answer 1

The correct option is D $\frac{9}{10}$

We know that angular kinetic energy =$\frac{I{\omega }^2}{2}$

For solid sphere I (about central axis) =$\frac{2}{5}M{R}^2$

Thus putting values we get angular kinetic energy = 0.9J