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Thread: mass of proton

  1. #1 mass of proton 
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    Someone told me that no two protons have the exact same mass. Are they full of crap? Because I thought that all protons had the same mass like electrons do.


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  3. #2  
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    They are full of crap. Protons contain an equal number of quarks. Maybe he was reffering to an antiproton as the second?


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    Sounds a bit strange, but I presume there are complications, particularly because of matter-energy equivalence.

    Off the top of my head (and I'm hoping better physicists will correct any nonsense I spout):

    1. There is a form of nuclear binding energy which means the mass of a proton in a nucleus is probably slightly different from an 'independent' proton.

    2. Protons tend to be very fast (outside the nucleus, that is), thanks to their electro-magnetic reactivity. Again, because the velocities can vary, I presume, continuously, the overall mass (including the added energy to reach that velocity, assuming it is a significant proportion of c) will vary continuously. I don't know if the difference is measurable in all cases, but theoretically, it might be possible to state that no free proton has 'exactly' (for a given definition of exact) the same mass as any other proton.

    Having said which, I suspect that yes, it is a bit of poppycock...
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    Quote Originally Posted by sunshinewarrio
    Sounds a bit strange, but I presume there are complications, particularly because of matter-energy equivalence.

    Off the top of my head (and I'm hoping better physicists will correct any nonsense I spout):

    1. There is a form of nuclear binding energy which means the mass of a proton in a nucleus is probably slightly different from an 'independent' proton.

    2. Protons tend to be very fast (outside the nucleus, that is), thanks to their electro-magnetic reactivity. Again, because the velocities can vary, I presume, continuously, the overall mass (including the added energy to reach that velocity, assuming it is a significant proportion of c) will vary continuously. I don't know if the difference is measurable in all cases, but theoretically, it might be possible to state that no free proton has 'exactly' (for a given definition of exact) the same mass as any other proton.

    Having said which, I suspect that yes, it is a bit of poppycock...
    Yes as Shanks said the mass of one can only be greater if it is faster than the other. If there was a diatomic molecule such as hydrogen, then if they rotate they would both from each others reference frame percieve one of the two more massive. But we would percieve the difference to be the same, its relativity again. I think whoever told you this is trying to prove that he may know relativity and brag about it, so beware and put it in his face that you know! Mass of a moving object is given in this formula:

    m = m0y

    Where m is the mass of the object
    Where m0 is the mass of the object at rest
    Where y is the Lorentz factor
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    What everyone has been saying about two protons having different masses if they're travelling at different velocities is true, but I believe that the masses of any two bound protons in a nucleus is the same, because if they weren't that would screw with the masses that we've assigned to each element.

    Another interesting little fact that goes along with the more velocity = more mass idea is that the masses of the constituent quarks of a proton (or neutron, or any hadron, really) don't nearly account for the protons mass - the majority of the mass actually comes from the energy in the strong-force bonds holding the quarks together.
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  7. #6  
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    Yeah my friend probably knows nothing or little about relativity, he wouldn't have looked into it that deep. I had never heard that before so I figured he was wrong. Thanks for the answers.
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    Quote Originally Posted by Chemboy
    What everyone has been saying about two protons having different masses if they're travelling at different velocities is true, but I believe that the masses of any two bound protons in a nucleus is the same, because if they weren't that would screw with the masses that we've assigned to each element.

    Another interesting little fact that goes along with the more velocity = more mass idea is that the masses of the constituent quarks of a proton (or neutron, or any hadron, really) don't nearly account for the protons mass - the majority of the mass actually comes from the energy in the strong-force bonds holding the quarks together.
    Relativity explains the SNF? Hm, interesting.
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  9. #8  
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    Quote Originally Posted by svwillmer
    Quote Originally Posted by Chemboy
    What everyone has been saying about two protons having different masses if they're travelling at different velocities is true, but I believe that the masses of any two bound protons in a nucleus is the same, because if they weren't that would screw with the masses that we've assigned to each element.

    Another interesting little fact that goes along with the more velocity = more mass idea is that the masses of the constituent quarks of a proton (or neutron, or any hadron, really) don't nearly account for the protons mass - the majority of the mass actually comes from the energy in the strong-force bonds holding the quarks together.
    Relativity explains the SNF? Hm, interesting.
    Darn it, I screwed that up. Sorry. "more velocity = more mass" should have been "more energy = more mass." The way I understand it, the energy of the gluons mediating the strong force adds most of the mass of a given hadron.
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  10. #9  
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    Quote Originally Posted by Chemboy
    Quote Originally Posted by svwillmer
    Quote Originally Posted by Chemboy
    What everyone has been saying about two protons having different masses if they're travelling at different velocities is true, but I believe that the masses of any two bound protons in a nucleus is the same, because if they weren't that would screw with the masses that we've assigned to each element.

    Another interesting little fact that goes along with the more velocity = more mass idea is that the masses of the constituent quarks of a proton (or neutron, or any hadron, really) don't nearly account for the protons mass - the majority of the mass actually comes from the energy in the strong-force bonds holding the quarks together.
    Relativity explains the SNF? Hm, interesting.
    Darn it, I screwed that up. Sorry. "more velocity = more mass" should have been "more energy = more mass." The way I understand it, the energy of the gluons mediating the strong force adds most of the mass of a given hadron.
    Don't it strike you that gluons and photons are very similar?
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  11. #10  
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    Quote Originally Posted by svwillmer
    Don't it strike you that gluons and photons are very similar?
    Doesn't it strike me that gluons and photons are similar? Well, they are. They're both gauge bosons, both have a spin of 1, both have a mass of 0. On the other hand, they mediate different forces, one 'feels' the force it carries and one doesn't, and one can't exist in a free state and the other can. What exactly are you getting at?
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  12. #11  
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    Quote Originally Posted by Chemboy
    Quote Originally Posted by svwillmer
    Don't it strike you that gluons and photons are very similar?
    Doesn't it strike me that gluons and photons are similar? Well, they are. They're both gauge bosons, both have a spin of 1, both have a mass of 0. On the other hand, they mediate different forces, one 'feels' the force it carries and one doesn't, and one can't exist in a free state and the other can. What exactly are you getting at?
    It's right in front of our eyes. Come on surely your not that gullable? :wink:
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  13. #12  
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    You should elaborate svwillmer because I have no idea what your hinting towards.
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