ACTIVITY 1 1. Compute the apparent mass of a negative charge traveling at a quarter of the speed of light. Rest mass = 9.31 x 1031 kg 2. What is the rest energy of a single proton? (rest mass = 1.67 x 10-27 kg) 3. An athlete knows from his knowledge of physics that, if he measures the earth a time interval on a moving spaceship, what he finds will be greater than what someone on the spaceship would measure. Is it a good idea for the athlete to set a world record for the 100-m dash by having his time taken by someone on a moving spaceship? 57