Help astronomy math problem!?

Question

Imagine that you have obtained spectra for several galaxies and have measured the redshift of each galaxy to determine its speed away from us. Here are your results:

Galaxy 1: Speed away from us is 15000 .

Galaxy 2: Speed away from us is 20000 .

Galaxy 3: Speed away from us is 25000 .

Estimate the distance to each galaxy from Hubble’s law. Assume that .

thats the ? you need to figure out glaxy 1, 2, and 3. I've used up almost all of my guessing points. Please help!

Answer 1

The Hubble constant was estimated to be about 70 kps per megaparsec in 1997.  I've heard some claim it 80 kps, but I'll stick to the HST version of 70.  So assuming your speeds are in kps, galaxy 1 is 214 million parsecs away (or 699 million light years).  Just divide the speed (in kps) by 70 to get millions of parsecs (then multiply by 3.262 to get millions of light years).

Answer 2

This is easy. You know what Hubble's Law means. Plug in Hubble's Constant and read off the answers.

Answer 3

Try this info:

http://en.wikipedia.org/wiki/Hubble%27s_...

DW