A meson when at rest decays 2 $\mu$s after it is created. If moving in the laboratory at 0.99c, its lifetime according to laboratory clocks would be:
A) the same
B) 0.28 s
C) 14 $\mu$s
D) 4.6 s
E) none of these

Question

Quizplus · Accepted Answer

According to time dilation, the lifetime of a moving particle is dilated, meaning it appears to last longer in the laboratory frame of reference than in its own rest frame. 
The formula for time dilation is:
t' = t/sqrt(1-(v^2/c^2))
where t is the proper time (lifetime in meson's rest frame), v is the velocity, and c is the speed of light. 
Plugging in the given values, we get:
t' = 2s / sqrt(1-0.99^2) = 14.14s, which is closest to choice C, 14μs.

A Meson When at Rest Decays 2 μ\muμ S After It Is Created

A Meson When at Rest Decays 2 $\mu$ S After It Is Created