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-   -   Ratio kinetic energy of alpha particle / kinetic energy of proton (http://www.physicsforums.com/showthread.php?t=308892)

385sk117 Apr21-09 02:17 PM

Ratio kinetic energy of alpha particle / kinetic energy of proton
 
1. The problem statement, all variables and given/known data
A photon and alpha particle are accelerated from rest through the same potential difference.
After acceleration what is the ratio kinetic energy of alpha particle / kinetic energy of proton?


2. Relevant equations
I guess I have to use eV = 1/2mv^2


3. The attempt at a solution
I dont know what value have to be used in place of e in equation eV = 1/2mv^2
the mass of alpha particle is approximately 4 times of photon and that's all i know
I guessed the answer as 4 but the answer was 2
I think there is something to do with the velocity of alpha particle and photon but i'm stucked can not think of anything..

ImAnEngineer Apr21-09 02:24 PM

Re: Ratio kinetic energy of alpha particle / kinetic energy of proton
 
An alfa particle has two protons, so that's twice the charge of one proton.

385sk117 Apr21-09 11:24 PM

Re: Ratio kinetic energy of alpha particle / kinetic energy of proton
 
Thanks a lot! So i didnt have to know the exact charges but the ratio


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