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Question about potential

  1. Jun 28, 2012 #1
    Let's say we have three objects, moon, earth and a ball.

    Suppose that the ball is in a point in space such that the gravity from the moon cancels out the gravity from the Earth, so that the net force on the ball is zero. Also assume that the ball is at rest.

    Then by Newton's laws, the ball will remain at rest.

    My question: What is the potential energy of the ball? I can calculate the potential energy due to the moon and the potential energy due to the earth, but will they cancel each other out because they are due to opposing forces? Or do they add up?

    Thanks.

    BiP
     
  2. jcsd
  3. Jun 28, 2012 #2

    Doc Al

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    Staff: Mentor

    The potential energies are scalars--they add accordingly.
     
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