Two equal masses travel in opposite directions with equal speeds.They collide in a collision that is between elastic and inelastic.Just after the collision,their velocities are
A)zero.
B)equal to their original velocities.
C)equal in magnitude but opposite in direction to their original velocities.
D)less in magnitude and in the same direction as their original velocities.
E)less in magnitude and opposite in direction to their original velocities.

Question

Quizplus · Accepted Answer

Since the collision is between elastic and inelastic, kinetic energy is not fully conserved, but momentum is. The two masses have equal speeds but opposite directions, so their momenta cancel out before the collision. After the collision, because it's not perfectly inelastic, they don't stick together but move apart with less kinetic energy, meaning their speeds are reduced. Their directions are opposite to their original directions because they have to move away from each other after the collision.

Two Equal Masses Travel in Opposite Directions with Equal Speeds