Cart A, with a mass of 0.2 kg, travels on a horizontal air track at 3 m/s and hits cart B, which has a mass of 0.4 kg and is initially at rest.After the collision the center of mass of the two cart system has a speed in m/s of:
A)0 m/s
B)1.0 m/s
C)2.3 m/s
D)2.5 m/s
E)5.0 m/s

Question

Quizplus · Accepted Answer

The speed of the center of mass of the system can be calculated using the formula for the conservation of momentum, which states that the total momentum before the collision is equal to the total momentum after the collision. Before the collision, only cart A has momentum, given by its mass times its velocity (0.2 kg * 3 m/s = 0.6 kg*m/s). Since cart B is at rest, its initial momentum is 0. The total mass of the system is 0.2 kg + 0.4 kg = 0.6 kg. The speed of the center of mass is the total momentum divided by the total mass, which is 0.6 kg*m/s / 0.6 kg = 1.0 m/s.

Cart A, with a Mass of 0