Hubble's Law

Galaxies appear to be speeding away from each other.  Radial velocity, called by astronomers, is apparent speed from the earth.
There is also the observance that the farther away a galaxy was, the faster it seems to be moving away from earth, thus, larger radial velocity.

Edwin Hubble, an astronomy, found that there is a mathematical relation between how far away a galacy is and how fast it is moving away from us.  The relation is called Hubble's Law.  Included in the relation is the Hubble constant 20 km/sec per million light years
 

  distance to galaxy = radial velocity of galaxy  
                              Hubble constant
Radial velocity is in kilometers per seconds.  The distance is in million of light years.    Using many measurements of distances and radial velocities, they can determine the values for Hubble constant.  There are several estimates for the Hubble constant.  Review the formula and equation of a galaxy that has a radial velocity -  1,000 kilometer per second. What is the distance of the galaxy?

 

distance = 1,000 km/sec  
20km/sec per million ly
               = 1,000 km/sec  
20km/sec per million ly
 
               = 1,000 million light years 
                       20 

           = 50  million light years 
 
 
Complete the following .

1.  If the radial velocity of a galaxy is 2,000 km.sec, what is the distance to the galaxy?
 
 
 
 

2.  If the radial velocity of agalaxy is 4,000 km/sec, what is the distance to the galaxy?
 
 
 
 

3.  The radial velocity of a galaxy in the constallation Virgo is about 1,200 km/sec.  What is the distance to the galaxy?
 
 
 
 
 

4.  A galaxy in the constellation Ursa Major is  moving away from earth at a bout 15,000km/sec.  What is the distance to the galaxy?
 
 
 
 
 

adapted from Mark Twain Media, Inc., Publishers