Question

question 5
2 pts
if galaxy a is four times more distant than galaxy b, then according to hubbles law, galaxy a will recede ____________ times faster than galaxy b.

Explanation:

Step1: Recall Hubble's Law

Hubble's Law is $v = H_0 d$, where $v$ is recessional velocity, $H_0$ is Hubble constant, and $d$ is distance.

Step2: Define distances of galaxies

Let distance of B be $d_B$, so distance of A: $d_A = 4d_B$.

Step3: Calculate velocities

Velocity of B: $v_B = H_0 d_B$; Velocity of A: $v_A = H_0 (4d_B) = 4H_0 d_B$.

Step4: Find ratio of velocities

$\frac{v_A}{v_B} = \frac{4H_0 d_B}{H_0 d_B} = 4$.

Answer:

4