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Collision detection between a moving circle and stationary point

  1. Aug 15, 2010 #1
    I'm trying to figure out the best way to find a collision between a moving circle and a stationary line segment. I have the x and y of the point, and the x, y, radius, x velocity, and y velocity of the circle.

    I tried using the equation of a circle with the origin at the point (P) and a radius equal to that of the original circle, and then solving that for x, substituting the equation for the line of motion of of the ball in place of y:


    I multiplied it all out and simplified it to standard form. Then I collected like terms and came up with these variables


    Then I used the quadratic formula to find the intercepts

    That should work, but it doesn't...
    Last edited: Aug 15, 2010
  2. jcsd
  3. Aug 15, 2010 #2
    Wow...never mind, I am an idiot...I forgot to subtract r2 before collecting terms!
  4. Aug 15, 2010 #3
    Oh...but this doesn't work if the circle has an x velocity of 0...How do I deal with that?
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