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: Unorthodox Conversions

  1. Sep 15, 2008 #1
    Ok, i know how to convert to and from the metric system and how to convert within, but what exactly am i supposed to do with this. Notice im not asking for it solved, but guidance on how to solve, bc this seems like a really stupid way for us to have to convert with extra steps added and mixed in. Also there is not much to work out by hand i believe other than writing and cancelling out. thank you. also i believe number seven is A
    Last edited: Sep 15, 2008
  2. jcsd
  3. Sep 15, 2008 #2
    Suppose you were stranded on a desert island and didn't have a table of conversion factors, and suppose also that you'd had a coconut fall from a tree and lost your memory of all but the most basic conversion factors. Using your remaing knowledge of simple unit ratios (12 inches / 1 ft, for example), you could write one of the expressions in #7 to convert m/s to mi/h.

    To start with mi/h and end with m/s, one must write a series of simple unit ratios, one of which has mi in the denominator (so as to 'cancel' mi from the final expression) and another of which that has m in the numerator (so we end up with m/s). The only answer to #7 that could be correct (can't see all of it) is answer e; its the only one that has a unit ratio with m in the numerator of one of the factors.

    This is just an exercise in writing and simplifying unit ratios, aka unit fractions.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook