Why Does a Solid Sphere Have Smaller

Answer: Since, the outer volume of the solid sphere is less than that of the hollow sphere, its moment of inertia is also less.

Why does a solid sphere have smaller moment?

But in case of a solid sphere, the same mass is distributed throughout at distance from zero to R from the axis of symmetry. Here, R is radius of cylinder/sphere. That is why a solid sphere has smaller moment of inertia than a hollow cylinder of same mass and radius.

How can you tell the difference between a hollow sphere and a solid sphere?

Since the moment of inertia of a hollow sphere is more than the moment of inertia of a solid sphere, hence we can say that the acceleration is greater for solid sphere than the hollow sphere. So the solid sphere reaches the bottom with greater speed. Hence the correct answer is option B.