Q. There are two identical balls of same material, one being solid and the other being hollow. How will you distinguish them without weighing?
A) By spinning them using equal torques
B) By determining their moment of inertia
C) By rolling them down an inclined plane
D) By any one of these methods
Explanation
(d) Solid and hollow balls can be distinguished by any of the three methods. $I_{h} > I_{s}$. When torques are equal, angular acceleration $\alpha$ of hollow must be smaller than $\alpha$ of solid. Similarly, on rolling, solid ball will reach the bottom before the hollow ball
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.