Sorry, I've been out sick all week. Its been a struggle with the whole family sick. Here are some more lecture notes on center of mass of and systems of particles. Read through those and the worked out examples.

There are also some essential practices problems. The ballistic pendulum. A basic collision comparing the results whether the collision is perfectly inelastic or perfectly elastic. And a collision with a spring between the block and you find the max compression of the spring. Try these in class today, solutions are posted below.