1. The problem statement, all variables and given/known data Two pendulums collide and stick together after being released from rest at angles given. (See diagram) What is the final swing angle of the stuck-together masses ? (I'm assuming my teacher means the angle when they get to the highest point in their swing) In what direction is the swing? 2. Relevant equations Conservation of Energy, Conservation of Momentum 3. The attempt at a solution I used cons. of e. to find both velocities just before impact, plugged that into cons. of momentum to get Φ in terms of θ, then used cons. of e. with initial being just as they hit and final being when they swing to a maximum height and got the height to be 5L(1-cosθ), which seems horribly, horribly wrong. Trying to go from there, I got the angle to be arccos(5cosθ-4), which can't be right either. Should I have approached this another way? I've done ballistic pendulum problems, but not when both are moving.