1. A 9 kg blob of putty moving at 10 m/s collides with an identical blob of putty at rest and they stick together. What speed do they move off together at?
2. A 25 kg boulder moving at 3 m/s collides with an identical boulder at rest and
they stick together. What speed do they move off together at?
3. A 40 kg girl and a 60 kg boy are both on ice skates. They push off of each other
and the girl moves at 5 m/s. What is the boy's speed?