A 2.8 kg block of wood sits on a frictionless table. A 3.0 g bullet, fired horizontally at a speed of 510 m/s , goes completely through the block, emerging at a speed of 210 m/s . What is the speed of the block immediately after the bullet exits?

Cuttlefish use jet propulsion to move rapidly. To do this, a cuttlefish fills its muscular mantle cavity with water and then quickly expels the water through a tube-like opening. The mass of a cuttlefish is about the same as the mass of water of the same volume. A 14-cm-long and 6.0-cm-wide cuttlefish, initially at rest, is moving at a speed of 4.0 m/sm/s after expelling the water from its body. Assume that the cuttlefish has a cylindrical form, the mantle cavity has a form of a cylinder with a length of 9.0 cm, and the thickness of the muscle surrounding the sides of the cavity is 1.0 cm. Estimate the speed of the expelled water relative to the sea bed. Express your answer with the appropriate units.

A 7.17 g pellet is shot horizontally from a BB gun at a speed of 24.8 m/s into a 28.7 g wooden block. The wooden block is attached to a spring and lies on a frictionless table. If the collision is inelastic and the spring constant k = 16.0 N/m, what is the maximum compression of the spring?

A 38.0-kg boy, riding a 1.90-kg skateboard at a velocity of 5.60 m/s across a level sidewalk, jumps forward to leap over a wall. Just after leaving contact with the board, the boy's velocity relative to the sidewalk is 6.00 m/s, 9.60° above the horizontal. Ignore any friction between the skateboard and the sidewalk. What is the skateboard's velocity relative to the sidewalk at this instant? Be sure to include the correct algebraic sign with your answer.