8.6 Exercise 1

Two cars of equal mass approach an intersection. Car A is moving east at a speed of 45 m/s. Car B is moving south at a speed of 35 m/s. They collide inelastically and stick together after the collision, moving as one object. Which of the following statements is true about the center-of-mass velocity of this system?

1. The center-of-mass velocity will decrease after the collision as a result of lost energy (but not drop to zero).
2. The center-of-mass velocity will remain the same after the collision since momentum is conserved.
3. The center-of-mass velocity will drop to zero since the two objects stick together.
4. The magnitude of the center-of-mass velocity will remain the same, but the direction of the velocity will change.