# A train car with mass m1 = 529 kg is moving to the right with a speed of v1 = 8.1 m/s and collides with a second train car.?

A train car with mass m1 = 529 kg is moving to the right with a speed of v1 = 8.1 m/s and collides with a second train car. The two cars latch together during the collision and then move off to the right at vf = 5.2 m/s.

1)What is the initial momentum of the first train car?

ans:4284.9 kg-m/s

2)What is the mass of the second train car?

ans:295.019 kg

3)What is the change in kinetic energy of the two train system during the collision?

J

4)Now the same two cars are involved in a second collision. The first car is again moving to the right with a speed of v1 = 8.1 m/s and collides with the second train car that is now moving to the left with a velocity v2 = -6 m/s before the collision. The two cars latch together at impact.

What is the final velocity of the two-car system? (A positive velocity means the two train cars move to the right – a negative velocity means the two train cars move to the left.)

m/s

5)Compare the magnitude of the momentum of train car 1 before and after the collision:

p1 initial = p1 final

p1 initial > p1 final

p1 initial < p1 final

### 2 Answers

- NCSLv 75 months agoFavorite Answer
3) change in KE

½*[(529+295)kg*(5.2m/s)² - 529kg*(8.1m/s)²] = -6213 J

indicating a loss of KE

4) conserve momentum

529kg*8.1m/s + 295kg*-6m/s = 824kg * V

V = 3.05 m/s

5) Clearly p1 initial > p1 final

Hope this helps!