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What is force ?

  1. Jun 30, 2007 #1
    What is "force"?


    As far as I know, there are two ways to look at force:

    1. A mathematical shorthand for the quantity [itex]ma[/itex] or [itex]\frac {dp}{dt}[/itex]. Someone got the bright idea that this particular quantity is useful in explaining a particular phenomenon in nature. "The heavier something is, and the faster I want to accelerate it, the more effort I will have to expend in order to push it. I will refer to this effort as 'force'."

    2. Force is an actual, physical influence that causes something to accelerate. This influence can be readily explained by one of the four fundamental interactions in nature: the strong and weak nuclear force, gravitational force, and electromagnetic force. Hence, any discussion about force must necessarily involve one of these interactions.

    Which viewpoint is the one that is considered more correct?
  2. jcsd
  3. Jun 30, 2007 #2


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    Well... the first is content free, in that "F=ma" doesn't really say anything if you simply take it as the definition of "F."
  4. Jul 1, 2007 #3

    Andrew Mason

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    They are both correct. Neither is "more correct" than the other.

    Force is a concept that exists independently of F=ma and it can be measured independently as well. We could define a unit of force as a certain displacement of a particular spring, for example. Or we could define a unit of force as the "weight" of a certain object. We could then apply various numbers of units of those forces to different masses and measure their acceleration and conclude that F = ma.

  5. Jul 1, 2007 #4
    Force is technically the net result of the electromagnetic forces experienced by the billions of atoms in the objects in question. Therefore, the electromagnetic force is technically the correct definition of force, however we use approximations, such as F = ma to make the calculations much more palatable, and frankly reasonable for humans to solve. F = ma is at its heart a model of the electromagnetic interactions that we experience on a daily basis.

    We could model the electromagnetic forces on each atom, and then sum them to find the net "force," however the computations involved are prohibitively expensive.
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