1. Spaceships A and B are traveling directly toward each other at a speed 0.5c relative to the Earth, and each has a headlight aimed toward the other ship. What value do technicians on ship B get by measuring the speed of the light emitted by ship A's headlight?
(a) 0.5c.
(b) 0.75c.
(c) 1.0c.
(d) 1.5c.
2. Relativistic formulas for time dilation, length contraction, and mass are valid
(a) Only for speeds less than 0.10c.
(b) Only for speeds greater than 0.10c.
(c) Only for speeds very close to c.
(d) For all speeds.