Relativity  laboratory reference frame
Hi everyone, I'm new in here and I need some help to figure out this problem.
A cosmic ray travels at a velocity v = 0.999c. The estimated life span in it's own frame reference is T = 1,22 * 10^6 s
Using the laboratory reference frame, how can I calculate the the average life span of the cosmic rays that travel at the speed of v=0,999c? and the distance traveled?
This is a simple problem but I can't figure it out quite well, can anyone give me some clues?
