A 71.80 kg person holding a steel ball stands motionless on a frozen lake. The person then throws the ball, which propels the person at 0.15 m/s to the
right and the ball 3.50 m/s to the left. If the initial momentum of the system is
zero, what is the mass of the steel ball?
A. 3.08 kg
B. 3.50 kg
O C. 20.51 kg
O D. 23.33 kg

You are driving directly behind a pickup truck, going at the same speed as the truck. a crate falls from the bed of the truck to the road. (a) will your car hit the crate before the crate hits the road if you neither brake nor swerve? (b) during the fall, is the horizontal speed of the crate more than, less than, or the same as that of the truck?