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Homework Help: Different way to solve projectile motion components?

  1. Oct 11, 2008 #1
    Different way to solve projectile motion components???

    1. The problem statement, all variables and given/known data
    solve projectile motion formulas for [tex]\Theta[/tex] and [tex]v_0[/tex]
    all measurements are in m, t is seconds
    [tex]y_0=.005[/tex]
    [tex]x_0=0[/tex]
    the averages from my trials were:
    [tex]x=8.775 m[/tex]
    [tex]t=1.3 s[/tex]

    2. Relevant equations
    [tex]x=x_0+v_0*cos\Theta*t[/tex]
    [tex]y=y_0+v_0*sin\Theta*t+.5a_yt^2[/tex]

    3. The attempt at a solution
    after plugging in my numbers gives:
    for x
    [tex]6.75=v_0*cos\Theta[/tex]
    which as far as I can see still has two unknowns, where do I go from here?

    I'm pretty confused about the y component because I'm not even sure what y is supposed to be. Don't I need a y(max) number first?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 11, 2008 #2

    Redbelly98

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    Re: Different way to solve projectile motion components???

    You don't need ymax necessarily.

    What is y when t=1.3s and x=8.775m?
     
  4. Oct 11, 2008 #3
    Re: Different way to solve projectile motion components???

    Alright, so I got some more insight from my roommate and managed to boil the equations down to:
    [tex]6.75=v_0Cos\Theta[/tex]
    and
    [tex]8.28=v_0Sin\Theta[/tex]

    am I headed in the right direction by then solving the x component for [tex]v_0=Cos\Theta[/tex] and then combining it with the y formula to get something like [tex]8.28=6.75Tan\Theta[/tex]?

    BTW I gave the wrong number for [tex]y_0[/tex]. It should be .0125 m. if you are actually checking my work
     
  5. Oct 11, 2008 #4

    Redbelly98

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    Re: Different way to solve projectile motion components???

    Looks like you're on the right track, though I'm not sure where [itex]8.28=v_0Sin\theta [/itex] comes from.
     
  6. Oct 11, 2008 #5
    Re: Different way to solve projectile motion components???

    does [tex]6.37=v_0Sin\theta[/tex] sound better?
     
  7. Oct 11, 2008 #6

    Redbelly98

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    Re: Different way to solve projectile motion components???

    Since I don't know what y is, I don't know.

    Welcome to PF, by the way.
     
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