A positive K meson (K+) is an unstable subatomic particle that decays into other particles. At rest, its mean lifetime is 1.23 * 10-8 s. (a) What do you measure the mean lifetime of a K+ to be if it is moving at 0.800c relative to you? (b) As measured from the reference frame of this K+, what is the mean lifetime of a second K+ that is at rest relative to you?

A positive K meson (K+) is an unstable subatomic particle that decays into other particles. At rest, its mean lifetime is 1.23 * 10-8 s. (a) What do you measure the mean lifetime of a K+ to be if it is moving at 0.800c relative to you? (b) As measured from the reference frame of this K+, what is the mean lifetime of a second K+ that is at rest relative to you?