Question

Two spheres have identical radii and much. How might you tell which of those spheres is hollow and which is solid?

Answer 1

Hint : Objects of equal mass and radius but different shape or solid/hollow will avalanche the incline at different rates. Solid sphere is quicker than solid cylinder since sphere has lower moment of inertia, higher translational K.E.

Complete Step By Step Answer:
You must have tried to seek out if an egg was boiled or raw by spinning it on the counter gently. Stopping it suddenly by putting a finger thereon then, releasing it immediately. We use a similar principle to unravel your problem.
We know that the instant of inertia of a sphere about its central axis and a skinny spherical shell (hollow sphere of your problem) is
Sphere, $I=25MR^2$.
Thin spherical shell, $I=23MR^2$, M and R the mass and radius of the sphere respectively.
We see that the spherical shell has more moments of inertia. (Check by making denominators equal for both). Now roll both the identical looking spheres down a machine lookout that neither of those slips. The expression between torque τ and moment of inertia is given by τ=Idωdt, where ω is the angular velocity.

Note :
The hollow sphere will have a greater moment of inertia because its entire mass is concentrated at the boundary of the sphere i.e., at maximum distance from the axis of rotation.