1. Why do you do no work on a 25- kg backpack when you walk a horizontal distance of 100 mm?

2. The Sun puts out twice as much solar energy in 2 hours as it does in 1 hour. But the solar power of the Sun is the same from one hour to the next. Distinguish between the terms solar energy and solar power.

3. Someone wanting to sell you a Superball claims that it will bounce to a height greater than the height from which it is dropped. Can this be?

4. What famous equation describes the relationship between mass and energy?

5. If two objects have equal kinetic energies, do they necessarily have the same momentum? Defend your answer.