## Conceptual Physics (12th Edition)

The final momentum vector P is the sum of the two initial momentum vectors, each with amount of momentum p. In terms of magnitude, $P=1.41p$.
The incoming momentum vectors are perpendicular. Use the Pythagorean theorem to find the magnitude of the combined momentum. $$p^{2}+p^{2}=P^{2}$$ $$P=1.41p$$