# Homework Help: Conservation of momentum

1. Dec 23, 2009

hi i am doing physics 30 by modules after doing it by class. and i am having a hard time working this question out.

A car with a mass of 1400kg is westbound at 50km/h. it collides at an intersection with a northbound truck having a mass of 2000kg and travelling at 40km/h. what is the inital common velocity of the car and truck immediatley after the collision if they have an inelastic collision?

i did all my conversions but i just cant figure out the proper steps in receiving the answer.

2. Dec 23, 2009

### denverdoc

Momentum should be conservered along both the x and y axes. Write some eqns to express the momenta before and after the collision--the mass of the car/truck is just the sum of the two individually.

3. Dec 23, 2009

so i dont really have to worry about the inelastic collision.
because i was stuck on that part.
just go along with finding the inital momentum and final and go from there?

4. Dec 23, 2009

### jegues

Inelastic collisions only effect the conservation of kinetic energy, not momentum.

5. Dec 24, 2009

### Redbelly98

Staff Emeritus
Yes.