Galaxy A has a velocity away from the Earth that is 3 times larger than the velocity of Galaxy B...?

Question

What do we know about Galaxy A? Pick one.

Galaxy A is 9 times more luminous than Galaxy B

Galaxy A is 3 times more massive than Galaxy B

Galaxy A is 1/3 the diameter of Galaxy B

Galaxy A is 3 times farther from the Earth than Galaxy B

Answer 1

None of the above because there is no information relating to its brightness (which eliminates answer 1), density (which eliminates 2), size (which eliminates 3) or original distance from the Earth (which eliminates 4).

Answer 2

This is a Hubbles law question

v= Hsubo (hubbles constant) x D (distance)

hence

D= v/ h

so as velocity increases so does distance example

v=1

d= 1/75(value for hubbles constant roughly)

d= 0.013

v=3

d=3/75

d=0.04

your answer is the last one

Answer 3

This is to do with the expansion of the universe. On average, the speed of a galaxy away from you is proportional to its distance.