1. You drive past a potential parking space in center city. Your new car is travelling at 85% the speed of light. If your car is 6.0 m long (which you measured the day you bought it) and you observe the space to be 3.0 m, should you try to park? Why is your friend on the sidewalk (who hasn't studied relativity) so sure that you can park? How does the situation appear to him?
2. Light requires 4.5 years to travel from the nearest star to earth. If we could travel there in a spaceship going 90% of the speed of light, the trip would require 5.0 years according to clocks on earth. How much time would pass for the passengers in the ship?
3. Astronaut Flo wishes to travel to a star 20 light years away and return. Her husband Malcolm, who was the same age as Flo when she departs, stays home (baking cookies). If Flo travels at a constand speed of 80% of the speed of light (except for a short time to turn around), how much younger than Malcolm will Flo be when she returns?
Hint--How long does Malcolm sit around baking cookies? How far is the distance to Flo?
4. The US uses about 8 x 1019 J of energy per year. How much mass would that require if we could totally convert mass to energy? If the mass came from, say, turning used cars entirely into energy, estimate how many would be required?