Question

Consider a completely elastic head-on collision between two particles that have the same mass and the same speed. What are the velocities after the collision? 

•  The magnitudes of the velocities are the same but the directions are reversed. 

•  One of the particles continues with the same velocity, and the other reverses direction at twice the speed. 

•  Both are zero. 

•  One of the particles continues with the same velocity, and the other comes to rest. 

•  More information is required to determine the final velocities.

Answer 1

In a perfectly elastic head-on collision, the velocities of the objects exchanged, and travel directions are reversed.

On the given case, the speeds of particle before Collison is same. Therefore, their speed is the same in magnitude after the collision, but the directions are reversed.

Thus, the correct option is the magnitudes of velocities are the same, but the directions are reversed.