Gravity and the Galaxies

[ecoli]

How much does gravity have an effect on galaxies pulling on each other? What is the gravity constant for a galaxy?

[ydoaPs]

the gravitational constant is about [math]6.67x10^{-11}[/math].

 

i think you meant gravitational acceleration. to get that, you need the mass of two galaxies, and their distance from each other.

 

[math]F=ma[/math]

 

[math]F=\frac{Gm_{1}m_{2}}{r^2}[/math]

 

now, substitute "ma" for "F"

 

[math]ma=\frac{Gm_{1}m_{2}}{r^2}[/math]

 

for this example, we are going to assume that the galaxies in question have the same mass, so that the masses cancel.

 

[math]a=\frac{Gm}{r^2}[/math]

 

put in a mass for m, distance for r, and approzxamately [math]6.67x10^{-11}[/math] for G

[ecoli]

Sorry, I did mean acceleration due to gravity.

 

How could you measure the mass of a galaxy?

[Severian]

How could you measure the mass of a galaxy?

 

From its acceleration due to gravity...