Question

[4] Answer the questions about the two galaxies below.

(a) Find the velocity of a galaxy if it is 8.22 Mpc away.
(b) Find the distance to a galaxy if it is moving away at a speed of 50,000 km/s.

Note: be sure to always use the formula sheet.

Answer: 592 km/s, 694 Mpc

Answer 1

a) Velocity of the galaxy=573.756 km/s

b) Distance to the galaxy=716 Mpc

Explanation:

a)
`v=H_0 D\\Where\ v=Velocity\ of\ the\ galaxy\\H_0= Hubble\ constant=69.8\pm 1.9\ as\ of\ 16\ July\ 2019\\D= Proper\ distance=8.22\ Mpc\\\Rightarrow v=69.8* 8.22\\\therefore v=573.756\ km/s\\`

b)
`v=H_0 D\\v=50000\ km/s\\H_0= Hubble\ constant=69.8\pm 1.9\\\Rightarrow D=(v)/(H_0)\\\Rightarrow D=(50000)/(69.8)\\\therefore D=716\ Mpc`