1. A boat that can travel with a velocity of 12 m/s in still water is moving at maximum speed against the current of a stream that flows with a velocity of 5 m/s relative to the Earth. What is the velocity of the boat relative to the bank of the stream?

3. A swimmer swims upstream with a velocity of 4 m/s rela-tive to the water. The velocity of the current is 3.5 m/s (downstream). What is the velocity of the swimmer relative to the bank?

5. An astronaut aims a flashlight toward the tail of his space- ship, which is traveling with a velocity of 0.5c relative to the Earth. What is the velocity of the light beam relative to the Earth?

7. An astronaut cooks a three-minute egg in his spaceship whizzing past Earth at a speed of 0.6c. How long has the egg cooked as measured by an observer on Earth?

9. A spaceship that is 50 m long as measured by its occupants is traveling at a speed of 0.1c relative to the Earth. How long is the spaceship as measured by mission control in Houston?

11. A spaceship is traveling with a velocity of 0.8c relative to the Earth. What is the momentum of the spaceship if its mass is 5000 kg? (p =rmv and c = 3 x 10^8 m/s.)