Solving Momentum Problem: Superman & Metropolis Express Collision

[runningirl]

Homework Statement

Lois Lane has been tied to the tracks and the Metropolis Express (m=200, 000 kg) is racing toward her at a velocity of +30 m/s. Superman (m=100kg) arrives just in time and comes hurtling at the train, collides with it, and stops it just before it runs over Lois. NOTE: Both Superman and the train come to a stop.

a)What was Man of Steel's velocity prior to his collision with the train?

b) It took 0.20 seconds for the train, and Superman, to come to a stop, what was the average force exerted by Superman on the train?

c) What was the average force exerted by the train on Superman?

Homework Equations

The Attempt at a Solution

i thought for part a:

200000(0)+100(v)=200000(30)+100(0)

v=6000 m/s?! it doesn't make sense..

part b)

J=Fave(t)
P=m(V)

100(v)=Fave(.2)

I realized i had to find Superman's velocity...

 

[cdotter]

Check your calculation, your answer is smaller than what it should be (by a factor of ten.)

But even with your smaller answer, why doesn't it make sense? A 200,000 kg train moving at 30 m/s has a lot of momentum.

 

[runningirl]

Check your calculation, your answer is smaller than what it should be (by a factor of ten.)

But even with your smaller answer, why doesn't it make sense? A 200,000 kg train moving at 30 m/s has a lot of momentum.

sorry, it was 60,000!
what does it mean for the average force exerted by the train on superman?!

 

[runningirl]

also, i got 60, 000, 000 N for part b...
which doesn't seem right for superman who has a mass of 100 kg..
Favg(.2)=100(60,000)