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Homework Help: AP Physics C lab involving incline planes featuring motion laws

  1. Aug 27, 2012 #1
    1. The problem statement, all variables and given/known data

    A dot on the floor with a diameter of 2cm.

    A table that is at a distance of 46cm horizontally from the center of said dot.

    The table is 90cm tall.

    The meat of the problem: A ping pong ball rolls off an incline plane (a wooden board) that is on top of the table. The incline plane must be some height. The ball must hit the table before it flies off the edge of the table. The ping pong ball must hit the dot on the floor.

    2. Relevant equations

    These are the formulas I believe to lead me to the answer:

    Rotational energy: 1/2(moment of inertia)(angular velocity)^2

    mgh = (1/2)mv^2

    3. The attempt at a solution

    At first I thought a simple formula of v=2√(height1)(height2) would solve it, untill I realized that it is only for objects having no mass......

    I am stumped on how to go about finding the appropriate variables in finding the height of the ramp.

    Primarily finding angular velocity
  2. jcsd
  3. Aug 27, 2012 #2
    Unless I am misunderstanding the setup, it seems to me rotational mechanics won't do you much good.

    Wouldn't it be better to find the velocity/angle that the ping pong ball would have to bounce off the table to land on the dot and then work backwards to figure out the ramp height?
  4. Aug 27, 2012 #3
    Dont I have to account for the mass of the ping pong ball?
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