Expert: Steve Holleran - 7/1/2007

Question
I am having trouble evaluating this equation.
44ft/s x 1 mi/5280 ft x 3,600 s/h. I would appreciate an idea on how to write this. It is like greek to me, and my text book does not show this particular scenario.

Answer
Hi Laura,

Well, it looks like a conversion from ft per sec to miles per hour.  You want it set up so that the units you want to get rid of cancel out, and the units you want to convert to are left.

The way it is set up, the "ft" will cancel and the "sec" will cancel, so after doing the arithmetic, the units will  be miles per hour:

    44 ft / 1 sec  * 1 mi / 5280 ft  * 3600 sec / 1 hr

 =  (44 * 3600) / 5280  mi / hr = 30 miles per hour.

Hope this is what you were asking.

Steve Holleran