Muons are elementary particles that decay like radioactive nuclei with a half-life of 1.5 μs. Consider a stream of nuclei at a speed of 0.9999c and aimed at an underground target d=800km. Assume that none of the muons interact with the earth as they travel to the target.
A) what is the half-life of the muons as measured by an observer stationary on the earth?
B) what fraction of the muons will reach the target before decaying?