Physics - Center of Mass Question with Solution | TestHub
Match the scenarios describing the motion of a system with the correct statement about its center of mass.
List - I | List - II |
|---|---|
(P) A system of two particles is moving under mutual gravitational attraction. The acceleration of its center of mass is... | (1) Zero |
(Q) A projectile explodes in mid-air into several fragments. The velocity of the center of mass of the fragments immediately after explosion is... | (2) Same as projectile's velocity before explosion |
(R) A block is placed on a frictionless horizontal surface. A constant horizontal force is applied to it. The acceleration of its center of mass is... | (3) |
(S) Two blocks are connected by a spring on a frictionless surface. They are pulled apart and released. The velocity of the center of mass of the system is... | (4) Constant (could be zero or non-zero) |
Options:
Answer:
Solution:
For P, mutual gravitational attraction is an internal force, so the net external force on the system is zero, making the acceleration of COM zero. For Q, explosion is an internal process, so the velocity of COM remains unchanged. For R, by Newton's second law for COM, , so . For S, the spring force is an internal force, and there are no external forces in the horizontal direction, so the velocity of COM remains constant. Since it was pulled apart and released from rest (relative to COM), the COM velocity remains zero.
