Quick question concerning conversions

1. Sep 11, 2006

wtf_albino

my book is rather vague on how to do unit conversions.

I have 60 Mi/H and need to get it into M/s.

Could i just set it up as:

[(60 Mi/H)(1609m)] / 3600 s

with this i come out to 26.8 m/s which sounds fairly correct.. am i making any errors?

2. Sep 11, 2006

JMuse

The easiest way, and the way usually taught, is to do each step seperately. So, you would have: $$\frac{60mi}{hr} * \frac{hr}{60min} * \frac{1min}{60sec} * \frac{1609meters}{1mi} = \frac{26.8meters}{sec}$$

The miles, hours, and minutes cancel out to give you meters/sec. You want to show how the units cancel out in your work, so in your calculation, you would want it to be 1609meters/mile and 1hr/3600seconds.

Last edited: Sep 11, 2006
3. Sep 11, 2006

Staff: Mentor

The answer is correct, but it would be less confusing if one would work out the steps.

60 mi/hr * (1609 m/mi) * (1 hr/3600 s) = 26.8 m/s. Show the ratios.

Also, one could realize that 1 mi = 5280 ft, and 60 mi/hr (60 mph) is the same as 88 ft/sec. Now 88 ft/s * (1 m/ 3.28084 ft) = 26.8 m/s, or 88 ft/s * 0.3048 m/ft = 26.8 m/s