**End Question: **

Suppose a freight-train car rolls along a track at 10 m/s and collides with an identical freight car at rest. The two cars couple together and move as one along the track. How fast do the coupled-cars move?

**HEWITT DREW IT
**

25. Conservation of Momentum

Paul shows how Newton’s laws lead to the impulse-momentum relationship, which then leads to the conservation of momentum.

**End Question: **

Suppose a freight-train car rolls along a track at 10 m/s and collides with an identical freight car at rest. The two cars couple together and move as one along the track. How fast do the coupled-cars move?