Rotation Curves & Dark Matter

Question 1

v stands for

Answer 1

velocity

Question 2

R stands for

Answer 2

Orbit size (radius)

Question 3

G

Answer 3

Gravitational constant

Question 4

v, drop off as 1/R^1/2 (inverse
square root).

Answer 4

Keplerian Rotation

Question 5

Keeping the mass the same, as you increase the radius, the velocity must fall off as the sqrt of 1 / R

Answer 5

My Keplerian rotation explanation

Question 6

rotation curve of the Milky way; evidence of dark matter

Answer 6

stays roughly flat at large radii

Question 7

Although there is no material beyond the visible edge; orbital speeds do not drop off; There is more gravity than accounted for by the stars

Answer 7

Evidence of dark matter

Question 8

If Area A has a curve increasing in both the radius and velocity, the enclosed mass will stay the same; increase; decrease?

Answer 8

increase because both radius and velocity are increasing

Question 9

If Area B has a curve increasing in the radius but the velocity remains the same, the enclosed mass will stay the same; increase; decrease?

Answer 9

increase, but slower than A; R is increasing but v remains constant.

Question 10

If Area C has a curve increasing in the radius but the velocity dropped off, the enclosed mass will stay the same; increase; decrease?

Answer 10

Stay the same; Total enclosed mass cannot decrease; the velocity fell off while radius increased which cancels the variables other out.

Question 11

If you know an object’s luminosity and measure its brightness, you can calculate its distance by ___

Answer 11

The inverse-square law

Question 12

a plot of the velocities (y-axis) vs. radial distance R (x-axis) of objects orbiting around the center of a galaxy

Answer 12

A rotation Curve Graph