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Eliminating time (t) between two equations

  1. Oct 1, 2012 #1
    I'm working through several example problems, and one thing that has come up a couple of times is where the person who solved these problems says "Eliminating t between equations (1)
    and (2) yields", or something similar. He's deriving an equation based on two other equations obviously, but I don't understand how or why (well, I sort of understand why, but...)

    So, in this instance, equation (1) is:
    [itex]x=V_{0x}t=(V_{0}Cos\Theta_{0})t[/itex]

    Equation (2) is:
    [itex]y=y_{0}+V_{0y}t+{1/2}a_{y}t^{2}[/itex]

    So, smashing them together (however you do that) and "eliminating t" (whatever that means, beyond the obvious), yields:
    [itex]y=y_{0}+(Tan\Theta_{0})x+({a_{y}/2v_{0}^{2}Cos^{2}\Theta_{0}})[/itex]
    I mean... I basically have that memorized now, but... how?
     
  2. jcsd
  3. Oct 1, 2012 #2
    it looks like he solved for t in the first equation and then substituted that in for t in equation 2
     
  4. Oct 1, 2012 #3
  5. Oct 1, 2012 #4
    ooooh, parametric equations... haven't started those yet (in my calc class).
    Thanks azizlwl!

    That's actually a good insight too, shishkabob.
    So, thanks to both of you.

    (actually, after skimming through that parametric equations tutorial, I think that we've started on this material... some of it, anyway. humm...)
     
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