Explain how you could convert a rate of 18,000 miles per hour to miles per second.

You could multiply that fraction by (1 hour / 3,600 seconds) .

               (18,000 mile / 1 hour) x (1 hour / 3,600 second) =

               (18,000 x 1) / (1 x 3,600)  (mile-hour) / (hour-second) =

                     (18,000 / 3,600)  (mile / second)  =  5 mile/second