3. The third graders are on one side of a schoolyard, and the fourth graders are on the other. They are throwing snow- balls at each other. Between them, snowballs of various masses are moving with different velocities as shown in Fig- ure OQ5.3. Rank the snowballs (a) through (e) according to the magnitude of the total force exerted on each one. Ignore air resistance. If two snowballs rank together, make that fact clear. 300 g 12 m/s 400 g 12 m/s b 200 g 9 m/s с 10 m/s a 8 m/s 500 g 400 g d e Figure OQ5.3

Firecracker a. A firecracker is at rest on a frictionless horizontal table. The firecracker explodes into two pieces of unequal mass that move in opposite directions on the table. Before i. Is the net force on the left piece always zero? Explain. After I1. Is the net force on the system consisting of both pieces always zero? Explain. iii. Is the momentum of the left piece conserved? Explain. 1V. Is the momentum of the system consisting of both pieces conserved? Explain.

Jenny and Betty are having a great time at Busch Gardens riding the Ubanga Banga bumper cars. Jenny, who is traveling southward in her bumper car, aims her car toward Betty, who is traveling northward in her bumper car. The cars collide and briefly come to a stop. What can you say about the magnitude of the force that Jenny's car exerts on Betty's car versus the magnitude of the force that Betty's car exerts on Jenny's car?

360 N marine in basic training climbs a 15 m vertical rope at uniform speed in 8 minutes. His output power