# Thread: Kinetic energy at v = c

1. Hi,
can anyone tell me what energy we must give a proton to reach 0.999 999 991 c?
It ought to be 3.5 or 7 TeV, can you show me how you do that?

2.

3. Originally Posted by whizkid
Hi,
can anyone tell me what energy we must give a proton to reach 0.999 999 991 c?
It ought to be 3.5 or 7 TeV, can you show me how you do that?

where is the rest mass of the proton and .

4. [QUOTE=xyzt;474899]
Originally Posted by whizkid
where is the rest mass of the proton and .
Thanks,xyzt,
938 000 000 eV*9*10^20/ 0.00134164 = 6,29 *10^33 eV.
If I skip c^2, I get 7*10^11 which is almost right, not quite so,
Where do I go wrong?

5. [QUOTE=whizkid;474905]
Originally Posted by xyzt
Originally Posted by whizkid
where is the rest mass of the proton and .
Thanks,xyzt,
938 000 000 eV*9*10^20/ 0.00134164 = 6,29 *10^33 eV. If I skip c^2 I get 7*10^11 which is almost right, not quite so, Where do I go wrong?

6. deleted

7. [QUOTE=xyzt;474907]
Originally Posted by whizkid
Thanks, and I dropped one 0 : 938 000 000: 0.000134 164= 7 TeV
Do you know why E is divided by c^2?

8. [QUOTE=whizkid;474911]
Originally Posted by xyzt
Originally Posted by whizkid
Thanks, and I dropped one 0 : 938 000 000: 0.000134 164= 7 TeV
Do you know why E is divided by c^2?
in order to express mass, .

9. Originally Posted by xyzt
Originally Posted by whizkid
Hi,
can anyone tell me what energy we must give a proton to reach 0.999 999 991 c?
It ought to be 3.5 or 7 TeV, can you show me how you do that?

where is the rest mass of the proton and .

Technically, if you are just looking for the kinetic energy.

Granted, at 0.999999991c, the two answers won't vary by much.

10. If I want to find 0.099...1, I can use the formula where M ( 7000 GeV/0.938 GeV = 7641 ) is mass increase (KE/m0*c^2)

Is there another way? I found this formula but can't use it

does it make sense to you?

11. Originally Posted by whizkid
If I want to find 0.099...1, I can use the formula where M ( 7000 GeV/0.938 GeV = 7641 ) is mass increase (KE/m0*c^2)

Is there another way? I found this formula but can't use it

does it make sense to you?
I have no idea what you are asking.

12. Originally Posted by whizkid
I found this formula but can't use it

For massless particles (i.e. photons) , therefore

From which . In other words the velocity of a photon is, not surprisingly, .

13. Originally Posted by Strange
Originally Posted by whizkid
I found this formula but can't use it

For massless particles (i.e. photons) , therefore
The other way around,

14. Originally Posted by xyzt
Originally Posted by Strange
Originally Posted by whizkid
I found this formula but can't use it

For massless particles (i.e. photons) , therefore
The other way around,
Doh. I meant (of course )

15. Thanks, everybody, for your help, so this:

is the only way to find v^2/c^2

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