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Point-like body

  1. Aug 5, 2005 #1
    my question is as follows:
    when do we need to consider a three dimension body as a point like body in our calclulations?
    i mean outside our theoretical/homework practices when should we assume the body as a point like?

    one thing i can think of is when the geometric properties of a body is not important and therefore isnt taken into consideration into our calculations.
    and maybe also when the body is a particle but other than that i dont know.
  2. jcsd
  3. Aug 5, 2005 #2
    When it makes it easier or possible to solve the problem.
  4. Aug 5, 2005 #3


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    Staff Emeritus
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    We can treat the Newtonian gravitational field (GM/r^2) of a spherically symmetric body as if the body were a point.

    The center of mass is a useful concept for the motion of rigid bodies as well. If we apply a force to a rigid body, we know that the acceleration of the center of mass is F/m.
  5. Aug 6, 2005 #4


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    I don't do much in the way of science other than haunting these premises. My experience with your question actually is the basis of how I play and teach pool. When calculating how to hit a ball, I treat each one as a mathematical point rather than a spherical object. I then envision what angle to fire a laser at in order to achieve the proper 'reflection', followed by extrapolating the radii in order to accommodate the edge-to-edge contact of the balls.
  6. Aug 6, 2005 #5
    and ofcourse you always lose... :rofl: :cry:
  7. Aug 6, 2005 #6


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    Gold Member

    Oooh... you sting me! (Wanna play for $$$? :tongue: )
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