PHYS 180 Lecture Notes - Lecture 5: Length Contraction, Nanosecond, 2D Computer Graphics
Document Summary
Length contraction occurs only along the direction of the motion but it stays the same width. It is a constellation of satellites which orbits the earth. Some move around the equator, some move around the poles. It is continually sending out this information in signal. At any particular time we can see many different satellites. In order for gps to work you have to see four different satelites. Based on this information you an use triangulation to determine your location. They key to gps is that you beed to measures your distance from each satellite is the speed of light times the time difference (the time light has been travelling). The satellites have a velocity of 140000km/hr. they lose 7 microseconds/day. Gps needs 50 nanosecond accuracy for 15 meter accuracy without special relativity you would lose 2 km/day. If you didn"t take into account the 7 microsecond/day loss you would lose 2km/day.
