OpenStax College Physics for AP® Courses, Chapter 28, Problem 36 (Problems & Exercises)

This is College Physics Answers with Shaun Dychko. An electron is traveling with a speed of 0.980c and the question is what is its relativistic momentum? That's going to equal the Lorentz factor multiplied by the electron's rest mass multiplied by its speed. So that's mu divided by square root 1 minus v squared over c squared when you replace γ with 1 over this denominator. So that's 9.11 times 10 to the minus 31 kilograms— rest mass of an electron— times 0.980 times the speed of light— 2.998 times 10 to the 8 meters per second— divided by square root of 1 minus 0.980c squared over c squared and that's 1.35 times 10 to the minus 21 kilogram meters per second.