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1			A sprinter crosses the start line (event 1) and runs at constant velocity until she crosses the finish line (event 2). In what reference frame would an observer measure the proper time interval between these two events? In what reference frame would an observer measure the proper length of the track from start line to finish line?
2			A particle with nonzero mass m can never move faster than the speed of light. Is there also a maximum momentum that the particle can have? A maximum kinetic energy? Explain.
3			The light-second is a unit of distance; 1 light-second is the distance that light travels in one second. (a) Find the conversion between light-seconds and meters: 1 light-second = ? m. (b) What is the speed of light in units of light-seconds per second?
4			An astronaut wears a new Rolex watch on a journey at a speed of 2.0 × 108 m/s with respect to Earth. According to mission control in Houston, the trip lasts 12.0 h. How long is the trip as measured on the Rolex?
5			A spaceship is traveling away from Earth at 0.87c. The astronauts report home by radio every 12 h (by their own clocks). At what interval are the reports sent to Earth, according to Earth clocks?
6			A spaceship is moving at a constant velocity of 0.70c relative to an Earth observer. The Earth observer measures the length of the spaceship to be 40.0 m. How long is the spaceship as measured by its pilot?
7			Particle A is moving with a constant velocity vAE = +0.90c relative to an Earth observer. Particle B moves in the opposite direction with a constant velocity vBE = -0.90c relative to the same Earth observer. What is the velocity of particle B as seen by particle A?
8			As observed from Earth, rocket Alpha moves with speed 0.90c and rocket Bravo travels with a speed of 0.60c. They are moving along the same line toward a head-on collision. What is the speed of rocket Alpha as measured from rocket Bravo?
9			Captain Kirk is measuring the speed of light in an evacuated chamber aboard a spaceship traveling with a constant velocity of 0.60c with respect to Earth. The light is moving in the direction of motion of the spaceship. Mr. Spock is on Earth watching the experiment. With what speed does the light in the vacuum chamber travel, according to Spock's observations?
10			An electron has momentum of magnitude 2.4 × 10-22 kg·m/s. What is the electron's speed?
11			An electron has a total energy of 6.5 MeV. What is its momentum (in MeV/c)?