Question

If the radius of solid sphere is doubled by keeping its mass constant ,compare the moment of inertia about any diameter.

Answer 1

Initially,

Mass = M

Radius = R

$I=\frac{2}{5}M{R}^2$

Now mass M

Radius = 2R

$I^{\prime }=\frac{2}{5}M(2R{)}^2$

$=4\left(\frac{2}{5}M{R}^2\right)$

= 4I

So, Become 4 time.