Question

Suppose a $W^{-}$ created in a bubble chamber lives for $5.00\times 10^{-25}\text{ s}$. What distance does it move in this time if it is travelling at $0.900c$? Since this distance is too short to make a track, the presence of the $W^{-}$ must be inferred from its decay products. Note that the time is longer than the given $W^{-}$ lifetime, which can be due to the statistical nature of decay or due to time dilation.