A spaceship passes a space-dock at speed 0.5 c. (A) Its length as measured by the space-dock personal is 121 m. What is its length as measured by ship's crew members aboard? (B) The space-ship reaches a planet called Theia in 9.2 days according to the time measured by the space-dock personal. What is this time interval as measured by the ship's captain? (C) Space-ship crew were playing a game on board which took them 65 min to finish one round. How long did the crew memebers take to complete one round of the game as measured by the space-dock personal?

Twins who are 19.0 years of age leave the earth and travel to a distant planet 12.0 light-years away. Assume that the planet and earth are at rest with respect to each other. The twins depart at the same time on different spaceships. One twin travels at a speed of 0.867c, and the other twin travels at 0.515c. (a) According to the theory of special relativity, what is the difference between their ages when they meet again at the earliest possible time? A₂-A₁ = i (b) Which twin is older?

1. You are an observer in a 100-m long spacecraft traveling from the earth to the moon at 0.8c. (a)What is the proper length of the spacecraft? (b) For a proper time interval of 1 sec., the relativistic time interval for the spacecraft measured from the earth reference frame would be: (c)Time dilation does not apply to all time-dependent physical and biological processes. T/F? (c) What is the relativistic length, DL measured from the reference frame of earth? (d) An APOLLO crew left a flat mirror reflector on the surface of the moon (for all you deniers out there, in the 50th anniversary year of APOLLO 11!). If the average surface-to-surface distance from the earth to the moon is 3.83 x 10^8 m, then how long does it take moonlight to reach earth?

How fast is a rocket going it its passengers measure its length to be 25.5 but the people on earth watching it go by measure its length to be 18.8? Please give your answer as a fraction of c. For example, if v=1.5*10^ 8 m/s,use V/c=0.5 .