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Homework Help: Centripetal force

  1. Feb 22, 2010 #1
    1. The problem statement, all variables and given/known data
    A 0.10 kilogram solid rubber ball is attached to the end of an 0.0 meter length of light thread. The ball is swung in a vertical circle. point P, the lowest point of the circle, is 0.20 meter above the floor. The speed of the ball at the top of the circle is 6.0 meters per second, and the total energy is kept constant.
    a)Determine the total energy of the ball, using the floor as the zero point for gravitational potential energy.

    b)Determine the speed of the ball at point P, the lowest point of the circle

    c)Determine the tension of the thread at...
    i. the top of the circle
    ii. the bottom of the circle

    The ball only reaches the top of the circle once before the thread breaks when the bal is at the lowest point of the circle.
    d)Determine the horizontal distance that the ball travels before hitting the floor

    2. Relevant equations

    PE + KE =TE
    a= m*v^2/r

    3. The attempt at a solution

    for part a, i know im supposed to use PE + KE = TE, but for "h" in PE, whats the height? Is it 1.8 meters?

    and then I'm not sure how to set up the rest of the parts.
    Any tips on how to set up the problem are appreciated.
  2. jcsd
  3. Feb 22, 2010 #2
    Length 0.0m?
    You need to combine the two eqns. you wrote by taking into account the acceleration towards center by the forces involved. Then eliminate v to get T.
  4. Feb 22, 2010 #3
    sorry length is 0.8meters
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