Question

A rotation curve, which plots the rotation speeds of objects as a function of their distance from the center of the Milky Way Galaxy, can be used to determine which property of the Galaxy?

Answer 1

The velocity curve

Explanation:

A plot of the rotation speed versus the distance from the center of the galaxy gives the movement of the galaxy. In essence, a rotation curve or the velocity curve is a plot of the orbital speeds in the galaxy as seen from the center of the galaxy.

Answer 2

The Mass distribution

Explanation:

Once you know the tangent speed v of a star which has an orbit of radius R around the center of the Galaxy, one can calculate the mass enclosed by such orbit.

As an estimation, consider the orbit as circular, then the newtonian force of gravity must account for the centripetal acceleration. In other words:

`(G M_(enclosed))/(R^(2) ) =(v^(2) )/(R)`

And so

`M_(enclosed)=(v^(2)R )/(G)`

Hope my answer helps.

Have a nice day!