- #1
jk4
I'm a little unsure about a certain part of this shown in a book.
There is an electron and a positron moving in the +x direction. They annihilate each other and release 2 photons. to conserve momentum 1 moves in the -x and one in the +x direction.
So then the first step is to do conservation of momentum: [tex]p_{1} - p_{2}[/tex] (photon momentum 1 - photon momentum 2). It's a (-) because the second photon moves in the -x direction.
Then we find conservation of energy: [tex]p_{1}c + p_{2}c[/tex]
(obviously we set these equations equal to the electron values, but I'm leaving that out.)
Ok, so, they find values for both of those equations. But, what I'm not sure of is the next step. It says
"Now we add the two results and solve for [tex]p_{1}[/tex] and [tex]p_{2}[/tex]
so it looks like:
[tex](p_{1} - p_{2}) + (p_{1} + p_{2})[/tex]
Then I understand the rest, I just don't know why they add the 2 values. Total Energy and net Momentum.
There is an electron and a positron moving in the +x direction. They annihilate each other and release 2 photons. to conserve momentum 1 moves in the -x and one in the +x direction.
So then the first step is to do conservation of momentum: [tex]p_{1} - p_{2}[/tex] (photon momentum 1 - photon momentum 2). It's a (-) because the second photon moves in the -x direction.
Then we find conservation of energy: [tex]p_{1}c + p_{2}c[/tex]
(obviously we set these equations equal to the electron values, but I'm leaving that out.)
Ok, so, they find values for both of those equations. But, what I'm not sure of is the next step. It says
"Now we add the two results and solve for [tex]p_{1}[/tex] and [tex]p_{2}[/tex]
so it looks like:
[tex](p_{1} - p_{2}) + (p_{1} + p_{2})[/tex]
Then I understand the rest, I just don't know why they add the 2 values. Total Energy and net Momentum.