# What are their velocities in m/s after the collision?

#### remaan

Hello every one,
I am new here, I 've just registered few minutes ago, and I wish I get the help I need.
My question is about collision, here is it:
Two of equal masses A and B have velocities of 6i m/s and -4i m/s respectivly. If they collide elastically, what are their velocities in m/s after the collision?

remaan

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#### berkeman

Mentor
Re: collision

Hello every one,
I am new here, I 've just registered few minutes ago, and I wish I get the help I need.
My question is about collision, here is it:
Two of equal masses A and B have velocities of 6i m/s and -4i m/s respectivly. If they collide elastically, what are their velocities in m/s after the collision?

remaan
Thread moved to Homework Help forums.

Welcome to the PF, remaan. You must show us the relevant equations and your attempt at a solution before we can help you. That's part of the PF rules for homework help.

How would you go about setting up this problem's solution?

#### remaan

Re: collision

I tried doing the following :
Because it is elastic colliosn, then the Enery and the momentom are conserved and I used the conservation of momentom

pi= pf
Ava+Bvb=AVaf+BVbf

and cancling the equal masses we get that the sum of their voliecities are equal in both cases, however, we still cannot say that have same velocities after the collison.

That was my attemp
Hope that works
remaan

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