1. The problem statement, all variables and given/known data Let a particle of mass 2M have an initial velocity of v0i (the i merely indicating it is traveling on the x axis) and undergo an elastic glancing collision with a particle of mass M initially at rest. After the collision, the M particle moves off at an angle of 45° above the + x-axis. 1. What is the speed of the M particle after the collision? 2. What is the velocity (magnitude and direction) of the mass 2M particle after the collision? m1 = 2M m2 = M v1i = v0i θ2 = 45° 2. Relevant equations pix = pfx (momentum conservation in the x direction) m1v1i = m1v1fcosθ1 + m2v2fcosθ2 piy = pfy (momentum conservation in the y direction) 0 = m1v1fsinθ1 + m2v2fsinθ2 Ki = Kf (conservation of kinetic energy) m1v1i2 = m1v1f2 + m2v2f2 3. The attempt at a solution It appears to be a 3 equations 3 unknowns problem (the unknowns being v2f, v1f, and θ1, which are the final velocities of the masses and the angle of mass 2M). I tried adding the two momentum equations to eliminate θ1 and get a new equation to use with the energy equation, that way I would have two equations and two unknowns. But I ended up finding a value for v1f to be -1.41v0i, meaning the ball of larger mass collided with the ball of half-mass, then started going in the opposite direction with a larger velocity, which makes no sense... Any help would be appreciated.