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Need help converting units, momentum of quark question 
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#1
Jan213, 06:18 AM

P: 40

1. The problem statement, all variables and given/known data
A proton has a diameter of about 1fm. Estimate the minimum momentum in units of MeV/C of a quark confined in a proton. 2. Relevant equations 3. The attempt at a solution I used the uncertainty relation [itex]\Delta[/itex]P[itex]\Delta[/itex]X ~ [itex]\frac{\hbar}{2}[/itex] [itex]\Delta[/itex]P ~ [itex]\frac{\hbar}{2 x 1x10^{15}}[/itex] = 5.276x10[itex]^{20}[/itex] kgm/s I'm unsure how to put this into MeV/C thanks 


#2
Jan213, 09:00 AM

Mentor
P: 11,815

You can convert kg in J/c^2 and that to MeV/c^2. Isolate a factor of c (based on m/s) and use this to cancel one c in the denominator.
Alternatively, use ℏ given in MeV/c * length. 


#3
Jan213, 11:27 AM

P: 40

And I ended up getting 2.96775x10[itex]^{16}[/itex]eV / C. the answer should be around 200 MeV/C 


#4
Jan213, 12:02 PM

Mentor
P: 11,815

Need help converting units, momentum of quark question
Did you consider m/s > c?
If I divide your value by 3*10^{8}, I get 10^{8}eV/c or ~100MeV/c. 


#5
Jan313, 05:17 AM

P: 40

Hmm that seems more correct, did I do the sum incorrectly?



#6
Jan313, 11:05 AM

Mentor
P: 11,815

I don't see a sum, but a missing factor of 3*10^8 would explain the difference.



#7
Jan313, 12:52 PM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,489




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