Halliday, Resnick & Walker — Center of Mass and Linear Momentum: Problem 67

67 In Fig. 9-58, particle 1 of mass $m_1 = 0.30 \text{ kg}$ slides rightward along an $x$ axis on a frictionless floor with a speed of $2.0 \text{ m/s}$. When it reaches $x = 0$, it undergoes a one-dimensional elastic collision with stationary particle 2 of mass $m_2 = 0.40 \text{ kg}$. When particle 2 then reaches a wall at $x_w = 70 \text{ cm}$, it bounces from the wall with no loss of speed. At what position on the $x$ axis does particle 2 then collide with particle 1?