1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I need a unit Conversion

  1. Jul 9, 2015 #1
    Hi ALL
    i need to unit Conversion :
    from: 28.8 Volts/(Meter/Second) to (.............) Volts/(Inch/Second)
    from: 28.8 Volts/(Meter/Second) to (.............) milliVolts/(milliMeter/Second)
  2. jcsd
  3. Jul 9, 2015 #2


    User Avatar
    Homework Helper

    Hi and welcome to PF!

    Volts = V
    Meter = m
    Second = s
    Inch = in


    So if you were given a problem that said, for example, the metal costs $10/m, then could you figure out how much it costs per inch instead? That is, what is the value of x such that


    If you can figure this out, then your problem is essentially the same because we can ignore the Volt-seconds in the numerators since they're both equivalent (think of them as merging into the $ symbol in my example).
  4. Jul 10, 2015 #3
    I do not understand your answer
    Do you can , give me more Explain

    Are you mean , like this:
    28.8 v(m/s) = 1135 v(in/s) ?????

    your example:$10/m to x$/in
    i thenk
    $10/39.4in = $0.254/in
  5. Jul 10, 2015 #4
    Thanks, now I understand (Excellent)

    1 m/s = 39.4 in/s
    28.8v/(m/s) / 39.4v/(in/s) = 0.73 v/(in/s)
    28.8v/(m/s) = 0.73 v/(in/s)
    it's good
    but,What about the second question
    from: 28.8v/(m/s) to (.........)mv/(mm/s) ???
  6. Jul 10, 2015 #5


    User Avatar
    Homework Helper

    You can make it more simple for yourself by ignoring a lot of the common units.
    We know that 1m = 39.4in, therefore we convert metres to inches by making that substitution wherever we see metres.
    And cancel all of the common units on both sides (which is the same as dividing both sides by [itex]V/(in/s)[/itex]) to get

    Now for the next question, again, do the substitutions as I've just shown you. 1000 millivolts = 1 volt, 1000mm = 1m.

    Note: remember we are striving for simplicity, so in your first problem, you could have cancelled common factors by going straight from

    by cancelling V/s. This helps to draw focus onto the problem at hand and not get messed up with all of the units.
  7. Jul 10, 2015 #6
    http://im86.gulfup.com/ckruO5.png [Broken]
    Last edited by a moderator: May 7, 2017
  8. Jul 10, 2015 #7


    User Avatar
    Homework Helper

    Very good, but you don't need to do it in 2 steps. Do it all in 1.

    Converting the LHS (left hand side):
    Cancelling the 1000's

    Hence x=28.8
  9. Jul 10, 2015 #8
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook