What is the Calculated Value of the Hubble Constant from Galaxy Observations?

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Homework Help Overview

The discussion revolves around calculating the Hubble Constant based on observations of a galaxy receding from the Sun at a specific velocity and distance. The subject area is cosmology, focusing on the relationship between velocity and distance in the context of Hubble's law.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of Hubble's equation and question the appropriate units for recessional velocity and distance. There is uncertainty about the correct mathematical operation to use in the calculation.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and clarifying the use of units in calculations. Some guidance has been offered regarding the need for unit conversion and the relationship between the quantities involved.

Contextual Notes

There is a mention of potential confusion regarding the units of measurement for recessional velocity and distance, as well as the mathematical operations required to find the Hubble Constant.

Solomon9$
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Homework Statement


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)?


Homework Equations





The Attempt at a Solution

 
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Do you know Hubble's equation?
 
Solomon9$ said:

Homework Statement


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)?


Homework Equations



recessional velocity = H^o x distance

The Attempt at a Solution


Not sure if recessional velocity in this equation is in km/s and distance in parsecs. Need help with this.
 
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.
 
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...
 
Subtract? :confused:
 
Sorry...it was late.

Divide.
 

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