An Electron with an Energy of 20 GeV (3

Multiple Choice

An electron with an energy of 20 GeV (3.20 × 10^-9 J) moving in the +x direction collides head on with a stationary proton. After the collision, the electron travels in the -x direction. What is the momentum of the electron after the collision? Note that this is an ultrarelativistic collision so that the energy of the moving masses can be approximated by the expression E ≈ pc. The mass of a proton is 1.67 × 10^-27 kg and that of an electron is 9.11 × 10^-31kg.

A) 2.5 × 10^-19 kg∙m/s
B) 5.0 × 10^-19 kg∙m/s
C) 1.1 × 10^-17 kg∙m/s
D) 2.2 × 10^-17 kg∙m/s
E) 2.7 × 10^-22 kg∙m/s