How Close to Light Speed Do Protons Move in the LHC?

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SUMMARY

The Large Hadron Collider (LHC) collides protons at a center-of-mass energy of 14 TeV, resulting in protons moving at approximately 20,000 m/s less than the speed of light, equivalent to 72,000 km/h. The calculations utilize the equation E = γmc² and the relativistic velocity addition formula to determine the relative speed of one proton to another. The discussion emphasizes the importance of maintaining accuracy by considering higher-order terms in the calculations, particularly when approximating velocities close to the speed of light.

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  • Understanding of special relativity and Lorentz transformations
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  • Knowledge of the Large Hadron Collider (LHC) and its operational parameters
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  • #31
PeroK said:
n the first method you used the approximation 1−ϵ1−ϵ1-\epsilon in the calculations for part b) and dropped the term in ϵ2ϵ2\epsilon^2 (which wasn't needed for part a). If you put that term back in, you should get the same answer as in the second method.
This was never an issue. The relation ##v=c(1-\epsilon)## from (a) is what defines ##\epsilon## and it is therefore exact. He only needs to keep terms to order ##\epsilon^2## when adding the velocities, which he did.
 
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  • #32
Orodruin said:
This was never an issue. The relation ##v=c(1-\epsilon)## from (a) is what defines ##\epsilon## and it is therefore exact. He only needs to keep terms to order ##\epsilon^2## when adding the velocities, which he did.

I thought the same.
 
  • #33
PeroK said:
Which is the order of ##\epsilon^2##.

In the first method you used the approximation ##1-\epsilon## in the calculations for part b) and dropped the term in ##\epsilon^2## (which wasn't needed for part a). If you put that term back in, you should get the same answer as in the second method.

Ignored this comment.

PeroK said:
You may also want to check that value for ##\epsilon##. Shouldn't it be approx ##10^{-8}##?

Showed the equivalence of the two approaches using this piece of advice.
 
  • #34
Thanks so much to vela, Orodruin and PeroK for helping me out with this problem with your suggestions and problem-solving tips!

I've learned a lot from solving just this one single problem. :smile:
 

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