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What's the relation between Mass Defect and the Strong Nuclear Force?

  1. Feb 1, 2014 #1
    Hello. Sorry for being annoying, I've posted like three questions today. But I'm studying nuclear chemistry and still somewhat confused regarding the binding energy and mass defect and their relation with the strong nuclear force..

    1) in this Hank Green video...

    He says that the mass defect is actually present in the form of energy that ties the nucleones together. Isn't that what the strong nuclear force does? Does this mean they're both the same thing? What's the relation between the two?

    2) in E=MC^2.. I can see why the mass defect matters to calculate the binding energy. but how does the speed of light constant matter in this case?

    3) Seeing that the binding energy is the energy needed to split the nucleones. and the strong nuclear force is what ties them together. Would it be correct to say they're opposites? and could they be calculated using that assumption?

    thanks in advance..
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Feb 1, 2014 #2


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    The mass defect is the result of the strong interaction (binding the nucleons together) and the electromagnetic interaction (as repulsive force between the protons), indeed.

    This comes from special relativity, and the factor depends on the unit system. You can use different units (called "natural units" as some constants like the speed of light are 1 there), where the equation is just E=M (better: E0=M, indicating that it is the rest energy).

    What do you mean with "opposites"?
    It is possible to estimate the nuclear binding energy with models for the strong and the electromagnetic interaction, yes. The result is the Semi-empirical mass formula.
  4. Feb 1, 2014 #3


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    The mass defect is obviously present in atoms. The mass of individual electrons, protons and neutrons is well known and they simply fall additively short of the measured mass of atoms.
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