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Homework Help: Repulsion between two pith balls

  1. Nov 22, 2004 #1
    i kinda need help. okay im posting my question:
    Two pith balls have a mass of 1.0g and have equal charges. One pith ball is suspended by an insulating thread. The other is attached to a static insulator and is brought close to the suspended ball so that they are 5 cm apart when repulsion occurs. After repulsion, they come to rest such that both are at the same height above ground. The suspended ball is now hanging with the thread forming a 30 degree angle with respect to its former position. Calculate the following:
    1-Force of weight of the suspended ball.
    2-The force of repulsion between the two. :confused: :confused:
    3-The net charge on each. :confused:
    I have no idea how to find out the force of repulsion and the net charge. We can find the weight my using the W=mg formula. So i'm confused with that. I need help :cry: . Thank God i found this cool forum
    Last edited: Nov 22, 2004
  2. jcsd
  3. Nov 22, 2004 #2


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    Staff Emeritus
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    Gold Member

    Start by drawing a force diagram. Since both balls are stationary you forces must all balance.
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