042-Fundamentals-of-Physics-II-Electromagnetism-Optics-and-Quantum-Mechanics-R.-Shankar-Edisi-1-2016 · Problem 1.1
Electrostatics I
Physics — Shankar · circular-orbit-dark-matter
Problem
For a star in a circular orbit of radius r around the center of a galaxy, the orbital velocity v satisfies
v2r=GM(1.9)
where M is the enclosed mass. Using this relation, explain how observations of stellar velocities at increasing orbital radii can be used to infer the existence of a dark matter halo in our galaxy.