Suppose that a beam of mesons (or pions) is moving with a velocity of 0.9c with

Suppose that a beam of π mesons (or pions) is moving with a velocity of 0.9c with respect to the laboratory. When the pions are at rest, they decay with a half-life of 1.77 x 10^-8 s.
a. Calculate the factor γ for the velocity of the pions relative to the laboratory.
b. What is the half-life of the moving pions as seen by an observer in the laboratory?
c. How far do the pions travel, as measured in the laboratory, before half have decayed?
d. As measured in a frame of reference that moves with the pions, how far do the pions travel before half have decayed?