Irodov Problem 1.346

The Particle moves very fast compared to someone in the Laboratory. Consequently, time will appear to be slower for the fast moving particle as seen from Laboratory reference frame. While in its own reference frame, the particle will decay exactly within its correct lifetime , to someone in the Laboratory reference frame this will appear to be a longer interval . The relation is given by,


This means that as seen in Laboratory, the particle would have traveled a distance of,