Why relativistic momentum equals the following?

In a solution to a problem we were given, it is written that a positron momentum with energy of 2mc2
(where γ=2) is √(γ2-1)*mc = √(4-1)*mc = √3*mc

How did they get that P=√(γ2-1)*mc?

Last edited by a moderator:

Related Introductory Physics Homework Help News on Phys.org
Nathanael
Homework Helper
You are familiar with p = ϒmv right?
And also with ϒ = 1/√(1-(v/c)2) right?

Eliminate v from the two equations and what do you get?

What I get is the answer thank you

Orodruin
Staff Emeritus
While it gives you the right answer, it is much simpler to use the energy-momentum relation $E^2 - p^2 c^2 = m^2 c^4$ and just solve for $p$.