Question

You run a 100-yd dash in 9.8 seconds. What is your speed in miles per hour?

Answer 1

20.90 mph

Explanation:

This is a problem that is employing conversion and conversion factors.

we'er given a yards per second speed, so need to convert yards to miles and seconds into hours.

`(100 y)/1` x# (5.68E^-4m)/(1 y)`=`.0568 m#

then we convert the seconds into hours

`(9.8 s)` x# (1m)/(60 s) `x` (1 h)/(60 m)`=`.0027 hr#

Now that you have the right units, you can use the speed equation

`S=D/T` = `.0568/.0027` =`20.90 mph`

It's important to note that when I did this calculations I did not round. Therefore, if you were to calculate `.0568/.0027` your answer would be slightly different due to rounding errors.