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Homework Help: Trouble with Projectile Motion

  1. Sep 29, 2010 #1
    I'm having trouble with projectile motion, mainly with understanding which formulas do what. I understand some, others I do not.
    Here are my formulas:

    Vx= V cos theta-- I know this is to find x components
    Vx= V sin theta-- I know this is to find y components

    tan theta=Ry/Rx-- I know i use my resultant x and y components in these, but I don't know what tan theta is.

    X=V0t-- I do not understand this formula

    Its mainly the V0x and V0y that I do not understand.

    Thank you for your help.
  2. jcsd
  3. Sep 29, 2010 #2


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    It's the tangent of the angle theta, which is most likely your incident angle.

    It has units of (m/s)*(s) = m. Therefore it is a distance. In the above example it'd be the distance in the x-direction.

    I think you might mean V0x and V0y? That's more or less standard notation for the initial velocity in the x or y directions.
  4. Sep 29, 2010 #3
    V0x and V0y are the initial vector components, I was confused on this too.
  5. Sep 29, 2010 #4
    Thank you,it's always the small things that can mess one up.
  6. Sep 29, 2010 #5
    this is for 1D motion and you travel at a constant velocity, so keep that in mind
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