Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Quick question concerning conversions

  1. Sep 11, 2006 #1
    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?

    sorry.. i'm very confused about this!:frown:
  2. jcsd
  3. Sep 11, 2006 #2
    The easiest way, and the way usually taught, is to do each step seperately. So, you would have: [tex]\frac{60mi}{hr} * \frac{hr}{60min} * \frac{1min}{60sec} * \frac{1609meters}{1mi} = \frac{26.8meters}{sec} [/tex]

    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
  4. Sep 11, 2006 #3


    User Avatar
    Staff Emeritus
    Science Advisor

    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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook