Question

2. Galaxy X in the Virgo Cluster has a cosmological redshift in its spectrum of z = 0.003 indicating it is moving away from us at 900 km/s. Galaxy Y has z = 0.015 a) Using z = v/c and our math shortcut, how fast is Galaxy Y moving away from us? (You can review the method in Box 23-2.)

Answer 1

Answer:

Speed of Galaxy Y is 4500 km/s

Explanation:

As we know that the Galaxy X has redshift given as

$z = \frac{v}{c}$

$0.003 = \frac{900 km/s}{c}$

$c = 3\times 10^5 km/s$

now in similar way for galaxy Y we have

$z = 0.015$

so we will have

$0.015 = \frac{v}{3 \times 10^5}$

$v = 4500 km/s$