Examples of use of Hubble's Law:

1. A galaxy is 100 Mpc away. What is its recession velocity due to the expansion of the Universe?
[Assume H₀ = 75 km/s/Mpc]

Hubble's Law: v = H₀ d
so v = (75 km/s/Mpc) x ( 100 Mpc )
and therefore
v = 7500 km/s



2. Say an object is located 10 kpc away. What is its velocity of recession due to the Hubble expansion?

v = H₀ d
v = ( 75 km/s/Mpc ) x ( 10 kpc )

reminder: 1 kpc = 1000 pc; 1 Mpc = 10⁶ pc

So
v = ( 75 km/s / 10⁶ pc ) x ( 10 x 1000 pc )
v = ( 75 km/s / 10⁶ pc ) x ( 10⁴ pc )
v = ( 75 km/s / 10² )
v = 75 km/s x 10^-2
v = 0.75 km/s