Momentum, impulse and collisions

Use this for “A 1 kg cart at 4 m/s meets a 3 kg cart coming the other way at 2 m/s. They bounce apart elastically. What are their velocities after?”

Use this for “A spring pushes a 1.5 kg cart and a 0.5 kg cart apart from rest. The big cart moves left at 1 m/s. How fast does the small one go, and how much energy did the spring give?”

Use this for “A 0.6 kg cart at 0.5 m/s meets a 0.4 kg cart rolling the other way at 0.25 m/s. The first cart slows to 0.1 m/s. How fast does the other cart move, and how much kinetic energy is lost?”

Use this for “A 0.2 kg ball at 25 m/s bounces straight back at 15 m/s after touching a wall for 0.05 s. What average force acts on it? Why would a softer wall push less hard?”