- #1
ajclarke
- 35
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Homework Statement
If a cosmic ray proton has 15J of energy how long, according to the proton's proper time would it take to travel from the galaxy M31 to our Galaxy, a distance that we mesure as 2.5x106 light-years?
Homework Equations
[tex]K.E = m_{o}c^2 (\gamma -1)[/tex]
The Attempt at a Solution
I work out [tex]\gamma[/tex] to be [tex]9.962 \times 10^{10}[/tex] and then using the usual equation for [tex]\gamma[/tex] I get the velocity to be c.
In our frame [tex]T=\frac{\Delta X}{c} = 7.89 \times 10^{13}[/tex] seconds
Proper time [tex]\tau=\frac{T}{\gamma}=\frac{7.89 \times 10^{13}}{9.962 \times 10^{10}} = 792.01[/tex] seconds.THis isn't for an assessment, I am revising for me end of year exam looking through past papers. Anyone give me some indication if this is correct and if not, where my mistakes are.
THanks a bunch.
Adam