Problem 1. A 70-kg person standing on a frictionless platform of ice throws a football forward with a velocity of 12m/s. If the person moves backward (sliding) with a velocity of
34cm/s, what is the mass of the football?

Problem 2. A car traveling at 8m/s crashes into a car of identical mass stopped at a traffic
light. What is the velocity of the wreckage immediately after the crash, assuming that the
cars stick together?
Problem 3. A 30-kg child stands on a frictionless surface. Th father throws a 0.8-kg football
with a velocity of 15m/s. What velocity will the child have after catching the football?

Problem 4. A billiard ball moving to the left at 30 cm/s collides head with another ball
moving to the right at 20cm/s. The masses of the balls are identical. If the collision is
perfectly elastic, what is the velocity of the first ball after impact if velocity of the second
ball is 4cm/s toward the right?

Problem 5. Two metal balls A and B are suspended, as shown in the figure, so that each
touches the other. The masses are given in the figure. Ball A is pulled to the initial side until it
is 12 cm above its initial position, and then it is released. If it strikes ball B in a completely
elastic collision, find the height h reached by ball B assuming zero friction.