- #1
iandelaney
- 4
- 0
Homework Statement
A cue ball with speed U hits a stationary red ball of equal mass. The collision is elastic (ie no energy is converted into other forms). After the collision the cue ball is moving at an angle θ to its original path. Find the final speed of the cue ball.
Homework Equations
conservation of momentum: mu=mv1mv2
conservation of energy: 1/2mu2 = 1/2mv12 + 1/2mv22
The Attempt at a Solution
As I understand it this should be a fairly standard problem but I have been struggling to find any help on the tinterweb hence my posting :-)
I know that from the conservation of momentum that the velocities of the two balls after the collision will be equal to the velocity of the cue ball initially. I would then like to substitute u=v1+v2 into the conservation of energy to obtain (v1+v2)2 = v12+v22 which is only the case when v1 and v2 are zero. I was wondering if anyone could spot my mistake?
thanks in advance
Ian