1. The problem statement, all variables and given/known data 2. Relevant equations MaVa+MbVb=MaV'a+MbV'b PE=mgh KE=.5mv^2 mgh=.5mv^2=KE of small ball just before collision 3. The attempt at a solution I first determined the starting height of the pendulum using the pythagorean theorem through sin15=y/.95 y=.2459 m .95-.2495m=.704 m above the x axis (where the pendulum would be vertical). I tried mgh (with h being .704m)=.5mv^2 v=3.715 m/s Ke just before collision: .5 mv^2 (small ball) + 0 = .5 mv'^2 (small ball) + .5 mv'^2 (big ball) I found the KE just before the collision to be 0.138 J, which is the left side of the above equation. The PE just before the collision is zero, and the PE when the balls reach their maximum height is mgh (small ball) + mgh (big ball) = 0.138 J (KE just before collision) Does it look like I'm on the right track? I'm not sure how to proceed - once I find out the final velocities of each ball (and I have no idea how to do that right now) will I then use kinematic equations to figure out how long until they reach their peak height and then find out how high that will allow them to go? Any help would be greatly appreciated!