Question

A bug travels at the rate of 3.0 miles per hour. How fast is this in um/nsec? Hint: 2.54cm = 1 inch and 1 mile = 5,280 feet

Answer 1

Note that
1 mi = 1609.34 m = 1609.34 x 10⁶ um
1 h = 3600 s = 3600 x 10⁹ ns

Therefore the speed of the bug is
 (3.0 mi/h)*(1609.34x10⁶ um/mi)*(1/3600x10⁹ h/ns)
$(3.0 \, \frac{mi}{h}) (1609.34\times10^{6}\, \frac{um}{mi} )( \frac{1}{3600\times 10^{9}} \frac{h}{ns} ) =1.34\,\times 10^{-3} \, \frac{um}{ns}$

Answer: $1.34 \times 10^{-3} \, \frac{\mu m}{ns}$