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Newton's First Law of Motion

  1. Aug 9, 2011 #1
    Forgive me if I'm missing a basic concept,

    A body does have a natural tendency to move, but a body does need energy to move! Where does this energy come from when no external force is applied on it?

    Please help, I've been pondering over this doubt since a week..
  2. jcsd
  3. Aug 9, 2011 #2

    Doc Al

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    Staff: Mentor

    It does not need additional energy to continue moving, but a moving body certainly has kinetic energy.
    If no external forces act on a body, it will continue its motion without the need for additional energy.
  4. Aug 9, 2011 #3
    So,the kinetic energy comes from it's initial velocity..?
  5. Aug 9, 2011 #4

    Doc Al

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    Staff: Mentor


    Newton's first law just says that if there are no external forces acting, then the body continues its motion at the same speed (and thus kinetic energy) in the same direction.

    External forces would be required to change the motion or the kinetic energy.
  6. Aug 9, 2011 #5
    Thankyou :)
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