Momentum math question?

Question

A 1.0-kg ball with a velocity of 5 m/sec hits another ball that is stationary. What is the momentum of each ball before the collision?

Answer 1

Well first of all you need to know the mass of the second ball but assuming that both balls have the same mass you use the following equation:

m1u1+m2u2=m1v1+m2v2

m= mass

u= velocity before collision

v= velocity after collision  

so you will have :

10x5+10+0=10x?+10x?

?= unknown vectors

60=10x? +10x?

Since 60 equals 2 equal vectors this means that we can divide 60 by them.

We only do this because we assumed that both ball have the same mass.

Thus 60/2=30      thus: 30=10x?   30/10=3

So you answer is as following

Each ball repel from each other at a speed of 3m/s

Answer 2

Ali aus found the momenta after the collision, but that wasn't the question, which was 'momentum of each ball before the collision.'

First ball: 5 kg-m/sec, second ball zero.

Which question did you intend to ask?