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Gravitational force: action and reaction

  1. Sep 24, 2009 #1
    Consider two particles 1 and 2 that can interact with each other but are isolated from their surroundings. If an internal force from particle 1, for example, a gravitational force, acts on particle 2, then there must be a second internal force—equal in magnitude but opposite in direction—that particle 2 exerts on particle 1.
    But if the particle 2 exerts a gravitational force too? Will the net force exerted on particle 1 be the sum of the gravitational forces 1 to 2 and 2 to 1?
  2. jcsd
  3. Sep 24, 2009 #2


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    the force is given by

    [tex]F=G \frac{m_1 m_2}{r^2}[/tex]

    the force on 1 = - force on 2

    so F1= -F2
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