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Gravitational force & escape velocity

  1. Sep 21, 2012 #1
    1- F = mk/r^2 ... k is -ve value ...why ?? please in concise way

    2- for escape velocity .......
    v( inital) = root ( 2gR ).... with proof

    thank u
  2. jcsd
  3. Sep 21, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Gravity is an attractive force, which acts in the -r direction.

    Prove it for yourself using conservation of energy.
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