A space ship travels with a constant speed of .8c as it passes by the Earth on its way to a distant star as shown in the diagram above.
a. the pilot of the spaceship measures the length of the moving ship as 20 meters. Determine its length as measure by a person on Earth.
b. The pilot of the spaceship observes that the spaceship travels for 5 years. Determine how much time has passed according to a person on Earth.
c. Some time after passing the Earth, the pilot shoots a laser pulse backward at a speed of 3x10^8 meters per second with respect to the spaceship. Determine the speed of the laser pulse as measure by a person on Earth.