For a two-body collision, involving objects with different masses, a frame of reference which has the same velocity relative to the laboratory as does the center of mass of the two objects is:
A)a frame for which the momentum of the incident object is zero
B)a frame for which the momentum of the target object is zero
C)a frame for which the average momentum of the two objects is zero
D)a frame for which the total momentum of the two objects is zero
E)none of the above

Question

Quizplus · Accepted Answer

In a two-body collision, the total momentum of the two objects is conserved. Therefore, in a frame of reference where the total momentum of the two objects is zero, the momentum before and after the collision is also zero. This frame of reference is called the center of mass frame, and it has the same velocity relative to the laboratory as the center of mass of the two objects. Therefore, the best choice is D.

For a Two-Body Collision, Involving Objects with Different Masses, a Frame