Question

A hollow sphere and a solid sphere having same mass and same radii are rolled down a rough inclined plane.

• A. The hollow sphere reaches the bottom first.
• B. The solid sphere reaches the bottom with greater speed.
• C. The solid sphere reaches the bottom with greater kinetic energy.
• D. The two spheres will reach the bottom with same linear momentum.

Answer 1

Answer: (B)

The solid sphere reaches the bottom with greater speed.

The solid sphere is has the moment of inertia as $\frac{2m{r}^2}{5}$ and that of hollow sphere is $\frac{2m{r}^2}{3}$. The moment of inertia for hollow sphere is larger thereby having a greater resistance to motion. Thus the solid sphere will have greater speed.