## Fundamentals of Physics Extended (10th Edition)

$\beta=1.7\times 10^{-12}$
To find the speed parameter beta, remember that $$\beta=\frac{v}{c}$$ The velocity must be in meters per second, so dimensional analysis must be performed. $$\frac{0.5mm}{1s}\times \frac{1m}{1000mm}=5\times 10^{-4}m/s$$ Substituting known values of $v=5\times 10^{-4}m/s$ and $c=3\times 10^8m/s$ yields a beta value of $$\beta=\frac{5\times 10^{-4}m/s}{3\times 10^8m/s}=1.7\times 10^{-12}$$