If a weighted air-filled balloon sinks in deep water, it will

An open freight car rolls friction-free along a horizontal track in vertically pouring rain. As water accumulates in the car, its speed

A flat piece of iron is tightly tied against top of a wooden block. The iron-wood block floats in a bucket of water. If the iron-wood block flips over so the iron is on the bottom, the water level at the side of the bucket

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will move in the opposite direction at

Just after a big fish swallows a small fish, the momentum of the two-fish system is

The total momentum of a flock of identical birds could be zero only if the birds are

A hunter aims a rifle at an angle of 10° below the horizontal. The hunter fires a bullet while simultaneously dropping another bullet from the side of the rifle. The bullet to hit the ground first is

A boxer punches a sheet of paper in midair from rest to a speed of 40 m/s in 0.05 s. If the mass of the paper is 0.01 kg, the force of the punch on the paper is

A bullet fired horizontally hits the ground in 0.5 s. If it had been fired with twice the velocity it would have hit the ground in

Using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 s. How much power does the elevator use?