# Kinetic energy of positron and proton

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1. Jul 9, 2016

### Gummy_Bear

1.e problem statement, all variables and given/known data
Two positrons and two protons are kept on the four corners of a square of side a. Positrons are kept at vertices A and C and protons are kept at B and D. let q denote the charge on both positron as well as the proton. So what is the kinetic energy of the positron and proton respectively after a long time ?

2. Relevant equations
I used the work energy theorem ie
Change in k.e. = wk. done
And work done = kq²/a

3. The attempt at a solution
First I calculated the kinetic energy of the positron due to all the 3 charges. I got the equation 2*kq²/a + kq²/root 2.
But the value that came after simplifying this equation did not match with the answer given in my book...

2. Jul 9, 2016

### TSny

Is this the complete statement of the problem? Are all four particles released from rest at the same time?

3. Jul 9, 2016

### Gummy_Bear

Yes this is the complete statement. I am also confused because i can't figure out how to solve it.

4. Jul 9, 2016

### TSny

Without knowing how many particles are released and whether or not they are released simultaneously, the question is ambiguous. The question states that the protons and positrons are "kept" on the corners of the square which could imply that none of the particles are able to move (which would make the problem fairly easy to solve ).

Last edited: Jul 9, 2016