Physics
posted by cat21 .
A 40 g marble moving at 2.3 m/s strikes a 29 g marble at rest. Assume the collision is perfectly elastic and the marbles collide headon. What is the speed of the first marble immediately after the collision? What is the speed of the second marble immediately after the collision?
How do you set this up?

two equations: Conservation of momentum
M1V1+m2(0)=M1V1' + m2V2'
solve for v2' in terms of all others.
second equation: conservation of energy
M1V1^2+0=M1V1'^2 + m2V2'^2
put the v2' equation into that equation, and solve for v1'
A bit of algebra is required, get a pad of paper. 
I tried plugging the number in and it didn't work...where are the numbers supposed to be placed in the first equation?