Problem 1. True or False: A rocket is fired upward and as it rises its speed increases.The work done by gravity on the rocket is therefore positive. Problem 2. True

or False: A piano is dropped from a high window. As it falls, the work done by gravity on the piano is positive. Problem 3. True or False: A rifle bullet is fired straight upward. As it rises, the work done by gravity on the bullet is negative. Problem 4. True or False: A hockey puck is gliding across a flat ice rink. The work done by gravity on the puck is zero, but the work done by friction is negative. Problem 5. True or False: Consider a piston-cylinder apparatus whose cylinder chamber is filled with a gas. If the gas expands by forcing the piston to move in the cylinder in such a way as to increase the volume of the chamber, then the work done by the gas on the piston is positive.