The mean lifetime of muons is $2.2 \mu \mathrm{s}$. How fast are they moving if their measured mean lifetime is $1.1 \mu \mathrm{s}$ ?
A) $0.56 \mathrm{c}$
B) $0.50 \mathrm{c}$
C) $0.94 \mathrm{c}$
D) $0.87 \mathrm{c}$
E) This cannot happen.

Question

Quizplus · Accepted Answer

The measured mean lifetime cannot be less than the proper mean lifetime due to time dilation effects in special relativity.

The Mean Lifetime of Muons Is 2.2μs2.2 \mu \mathrm{s}2.2μs How Fast Are They Moving If Their Measured Mean

The Mean Lifetime of Muons Is $2.2 \mu \mathrm{s}$ How Fast Are They Moving If Their Measured Mean