Homework Help: Velocity and momentum?

stargirl17 · Mar 7, 2010

1. The problem statement, all variables and given/known data

A 24,000 kg box car travelling north at 2 m/s collides with an 18,000 kg box car. Upon collision the two box cars lock together. What is the velocity of the 18,000 box car before the collision if after the collision the two box cars are traveling south at 1 m/s?

2. Relevant equations

MaVai + MbVBi = MaMaf + MbVbf

3. The attempt at a solution

lightgrav · Mar 7, 2010

what does "locked together" mean ? (show this on your "after" diagram)

stargirl17 · Mar 7, 2010

like the cars combined

lightgrav · Mar 7, 2010

so, what is v_a,f ? ... what is v_b,f ?

stargirl17 · Mar 7, 2010

mass of a, velocity of a initial etc

lightgrav · Mar 7, 2010

don't you know _numerical_values_ for the velocities afterward ?

Interceptor_1 · Mar 7, 2010

It is a case of a complete inelastic collision,the two carts will move together with a common velocity.
m1v1 +m2(-v2)=(m1+m2)v