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The problem described with image in topic

  1. Nov 4, 2011 #1
    [PLAIN]http://img842.imageshack.us/img842/336/angleqj.png [Broken]
    Lets say that the body has force F in the direction B(β).
    What is the formula that would let me calculate X velocity and Y velocity of the body?
    The formula should include all three factors, A(α), B(β), and F (force of the body)

    I've encountered this problem while developing computer game. Thanks for help!
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Nov 4, 2011 #2
    Create a right triangle with F as the hypotenuse and one side being the X Velocity and the other side being the Y velocity. Then if you know the angle of the object, you can use right-angle trig to figure out the other sides.

    Sorry about the error in posting, accidentally pressed 'post quick reply' instead of 'go advanced.'
    Last edited: Nov 4, 2011
  4. Nov 4, 2011 #3
    I can only include 1 angle (α) and force in right triangle (other angle will always be 90-α).
  5. Nov 4, 2011 #4
    You only need one angle and one side.
  6. Nov 4, 2011 #5
    For the angle I take γ=α-β
    From that I get that X velocity = cosγ*F and Y velocity = sinγ*F
    Now lets say that α=0 and β=-90. It's obvious that both X and Y velocities are equal to 0. But from the equations above I get that X velocity = 0 while Y velocity = F which is wrong.
  7. Nov 4, 2011 #6
    No they wouldn't both be zero. If F is only in one direction, one vector will have all of the force and the other will have none.
  8. Nov 4, 2011 #7
    Yes all the force would be in Y direction, but it just couldn't be applied so Y velocity would still be 0.
  9. Nov 5, 2011 #8
    I don't understand what's wrong, if you just use right angle trig I know it will work out, it's basic vectors.
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