Question

A stone of mass $4\text{kg}$ is whirled in a horizontal circle of radius $1\text{m}$ with angular speed of $2\text{rev/sec}$. The moment of inertia of the stone about the axis of rotation is

• A. $64{\text{kg m}}^2$
• B. $4{\text{kg m}}^2$
• C. $16{\text{kg m}}^2$
• D. $1{\text{kg m}}^2$

Answer 1

The correct option is B $4{\text{kg m}}^2$

Given :
$m=4\text{kg},r=1m$
Moment of inertia about axis of rotation $I=m{r}^2=4{\text{kg m}}^2$