I've got one...
The mean lifetime of a pion = 2.6 x 10^-8 seconds.
If a beam of pions has a speed of 0.85c, where c=speed of light, what would their measured lifetime be in a labarotory?
This is the kinda shit thats on my exam on Tuesday
Studying for an Astrophysics degree is my fulltime 'dayjob'