Lorenzo rides his bike at a rate of 2.2 meters per second. About how many miles per hour can Lorenzo ride his bike?

Question

 In the chapter Convert Measurements lesson Convert Rates.

Answer 1

The way in which I figure out how to multiply conversion rates to get the desired outcome is to set up
my units like fractions ....

First I need to change m/sec to ft/sec so I multiply (m/sec)(ft/m)

 

Looking up the conversion chart I see that 1m = 3.2808399 ft.

If I want to change meters to feet then I multiply the number of meters by that conversion factor

Thus:  (2.2 m/sec)(3.2808399 ft/m) = 7.21784778 ft/sec

 

Looking at my units as fractions I need to change ft/sec to ft/hr

(ft/sec)(sec/min)(min/hr) = ft/hr

 

So..   (7.21784778 ft/sec)(60 sec/min)(60 min/hr) = (7.21784778)(60)(60)ft/hr = 25985.25201 ft/hr

 

All that is left is to convert ft/hr to miles/hr:  Note that (ft/hr)(miles/ft) will give miles/hr

 

There are 5,280 ft in a mile so the conversion factor of miles/ft is 1mi/5280ft

 

(25985.25201 ft/hr) (1/5280 mi/ft) = 25985.25201/5280 mi/hr = 4.92125985 mph

 

Round this to the desired decimal place and Lorenzo rides his bike approximately 4.92 mph

 

Note this is the same answer Chris arrived at below:  I merely tried to explain the conversion process step by step as I went through the problem.  I hope this helps.

Answer 2

For unit conversion, I like to cancel units out as we go through the problem...

 

(2.2 m/s) * (3600 s/hr) * (1/1000 km/m) * (1/1.60934 mi/km)

 

If you go through each step above, you convert from meters per second to meters per hour, then to kilometers per hour, and finally to miles per hour.

 

=4.92 miles per hour