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Collision questions (physics) please help?
Two train cars, with masses of 1000 kg and 4000 kg, are joined together with a heavy duty spring compressed between them. The cars roll together with negligible friction along a straight and level track at a speed of 20 m/s. The connection between cars is broken, and the spring pushes them apart. After being separated, the 1000-kg car rolls at a speed of 8 m/s. How fast is the 4000-kg car moving now?
The answer is 23 m/s but I have no idea how to get there. My final is at 12:20 today. Would someone PLEASE break this down for me? I'm desperate.
1 Answer
- Andrew SmithLv 78 years agoFavorite Answer
Momentum is conserved.
Prior to releasing the spring the momentum was mv = 5000 * 20 = 100000kg m/s
After the collision the total must be the same.
1000 * 8 + 4000 * v = 100000
4000 * v = 92000
v = 92000/4000 = 23 m/s
