Question

A particle travels at 1.90×10⁸ m/s and lives 2.10×10⁻⁸ s when at rest relative to an observer. How long does the particle live as viewed in the laboratory?

c = 3.0×10⁸

Answer 1

$t=\frac{t_0}{\sqrt{1-\frac{v^2}{c^2}}}=2.7\cdot 10^{-8}~s.$