# Homework Help: Hubble Constant (in km/s/Mpc)

1. Mar 17, 2010

### Solomon9$1. The problem statement, all variables and given/known data A galaxy is observed to be receding from the Sun with a velocity of 7500 km/s. The distance to the galaxy is determined to be 1.4×10^8 parsecs. From this observation, what is the value of the Hubble Constant (in km/s/Mpc)? 2. Relevant equations 3. The attempt at a solution 2. Mar 17, 2010 ### ideasrule Do you know Hubble's equation? 3. Mar 17, 2010 ### Solomon9$

Not sure if recessional velocity in this equation is in km/s and distance in parsecs. Need help with this.

4. Mar 17, 2010

### ideasrule

For any equation in physics, it doesn't matter what units you use; a relationship between physical quantities doesn't depend on how said physical quantities are measured. However, you do have to include the units in your calculations and convert when appropriate.

5. Mar 17, 2010

### Solomon9$so am I to simply subtract 7500 km/s from 1.4×108 parsecs to solve for Hubble Constant (in km/s/Mpc)? Seems too easy... 6. Mar 17, 2010 ### ideasrule Subtract? 7. Mar 18, 2010 ### Solomon9$

Sorry...it was late.

Divide.