Question

Three identical particles are located at the vertices of an equilateral triangle. Each particle moves along a meridian with equal speed towards the centroid and collides inelastically.

• A. All the three particles will bounce back along the meridians with lesser speed.
• B. All the three particles will become stationary.
• C. All the particles will continue to move in their original directions but with lesser speed.
• D. Nothing can be said.

Answer 1

Answer: (D)

Nothing can be said.

Momentum of the three particle system will be conserved since there is no external force.
Option(A): We cannot say about its correctness from only momentum conservation.
Option(B): Though initial momentum and final momentum are zero, the particles can move after collision and make the final momentum zero also. Hence, it is incorrect.
Option(C): Since kinetic energy energy is not conserved in inelastic collision, it is possible that they will move with lesser speed but we cannot say that the particles will move in the original directions. Hence, it is incorrect.
Option(D): correct.