- #1
Kreamer
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Homework Statement
A positron is a particle that has the same mass but opposite charge of an electron. An electron and a positron are shot directly toward each other by a particle accelerator. They start very far from each other, each with a kinetic energy of 5 × 10−14 J. When they collide, they disintegrate and completely transform into two photons. What is the total (combined) kinetic energy of the two photons after the collision?
A. 8 × 10−14J
B. 1.6 × 10−14J
C. 1.0 × 10−13 J
D. 2.6 × 10−13J
E. 1.3 × 10−13 J
The attempt at a solution
I know the answer is D. 2.6 x 10-13J from an answer key however I am a little confused as to how to get that answer.
First I started thinking about how momentum is always conserved however photons have no mass so the momentum of the photons is 0 correct? So how is momentum conserved? And how is the answer D?