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Homework Help: Motion in a Circle Problem

  1. Oct 23, 2006 #1

    There is an inverted cone with height h. There is a ball rolling around inside creating a horizontal circle. The height from the tip of the inverted cone to the ball is y. a is given from the center of the cone to the outer edge.

    The question asks to express the ball's speed in terms of a, h, y, and g.

    I am confused as to why a is shown from the center of the cone to the edge. Is a in this case the same as acceleration?

    I know a = w^2 * r as well as a = (v^2)/r
    I have the forces in the y-direction: N = mg
    I have the forces in the x-direction: (h-y)sin(theta) = (mv^2)/r

    I believe I am screwing up on the x-direction forces. Any suggestions?

    Thank you very much,
  2. jcsd
  3. Oct 24, 2006 #2
    The normal force is perpendicular to the surface. That's not where you put it in your force equation. That will also help you fix the force equations for X.

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