Question

If an object's rotational kinetic energy is 64 j and it rotates with an angular speed of 10 radians/s, what is its moment of inertia?

Answer 1

The rotational kinetic energy of an object is given by

`E= (1)/(2) I \omega^2`
where I is the moment of inertia of the object and
`\omega` its angular speed.

Re-arranging the formula, we find

`I= (2E)/(\omega^2)`
and by using
`E=64 J` and
`\omega=10 rad/s`, we find

`I= (2 \cdot 64 J)/((10 rad/s)^2)=1.28 J s^2`