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Homework Help: Deriving an equation?

  1. Oct 1, 2012 #1
    1. The problem statement, all variables and given/known data
    Can you come up with (i.e. derive) equations 5-1 and 5-2 on your own using UAM equations? Try it

    2. Relevant equations

    This is the equation I need to end up at...


    3. The attempt at a solution

    I am not really sure where to start. I was trying to use the equations for range and height but it does not seem to be getting me anywhere. This is my first physics course.
  2. jcsd
  3. Oct 1, 2012 #2


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    Science Advisor
    Homework Helper

    welcome to pf!

    hi jensgt! welcome to pf! :smile:

    (try using the X2 button just above the Reply box :wink:)

    don't try to memorise (or use) the range or height equations :wink:, go back to the standard constant acceleration equations, for the x and y directions (separately)

    they'll use the same t …

    show us what you get :smile:
  4. Oct 1, 2012 #3
    The equations I know are

    Vx = Vox + Axt

    X = Xo + Voxt + 1/2axt^2

    X-Xo = [(Vox + Vx)/2]t

    Vx^2 = Vox^2 +2ax(X-Xo)

    I am just confused as to where to start. I derived the other one he asked us about this one has me stuck.
  5. Oct 2, 2012 #4


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    hi jensgt! :smile:

    (just got up :zzz:)
    use x = xo + Vxot + 1/2axt2

    and y = yo + Vyot + 1/2ayt2

    (obviously, ax = 0) …

    show us what you get :smile:

    (btw, never use "x" for times, it's too confusing … use "*" instead, or nothing at all! :wink:)
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