You and your friends are tubing down the San Marcos River. Your friend and his tube have a combined mass of 100 kg
and are initially drifting at 4 m/s. You and your tube have a combined mass 20 kg and are drifting directly in front of him at 1 m/s. When you collide, you grab onto your friend's tube and travel together.
a. What kind of collision is this?
b. What is the final speed of your tubes?