particle 1 of mass m1 = 0.29 kg slides rightward along an x axis on a frictionless floor with a speed of 1.8 m/s. When it reaches x = 0, it undergoes a one-dimensional elastic collision with stationary particle 2 of mass m2 = 0.40 kg. When particle 2 then reaches a wall at xw = 70 cm, it bounces from it with no loss of speed. At what position on the x axis does particle 2 then collide with particle 1?

How do i set this problem up?

2 answers

The first collision (conservation of energy, momentum) gives you the speeds of M1 and m2 after the collision. Then, the distance m2 travels is 70 cm + (70-x) cm. But it does it in the same time as m1 travel x cm. You have the distances, velocitys, and times, solve for x.
ok so velocity of m1 = 150 m/s and m2 = -29 m/s.....where do i go from there?