Where does the value of G come from in displacement experiments?

AI Thread Summary
The gravitational constant G, valued at 0.0000000000667, is derived from experiments by Henry Cavendish and Philip von Jolly, which measure the force between masses without explicitly timing the displacement. The numerical value of G is influenced by humanity's choice of units for distance, time, and mass, leading to its specific representation. G is one of the least accurately measured constants, with only six significant figures, and its value may be unique to our universe, potentially differing in others. Understanding G requires applying Newton's law of gravitation, and resources are available for laymen to grasp this concept. The discussion highlights the interplay between measurement, units, and fundamental physics in defining gravitational interactions.
omin
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The magnitude of G is the same as the magnitude of the force between two masses of 1 kilogram each, I meter apart: 0.0000000000667.

Where does 0.0000000000667 come from?

G is an acclerlation rate. The experiments in my text from Henry Cavendish and Philip von Jolly. Both experients seem to only show a displacement rather than the time the displacement occurs. Wouldn't they have to know in the experiment the time the displacement occurs to get the constant G? If they didn't test for the time, how did they get it from the experiment?
 
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Well, not to be pedantic, but the numerical value of G is simply a result of mankind's arbitrarily-chosen units of distance, time, and mass. In many situations, physicists use natural units in which G (and other constants) are simply unity.

- Warren
 
To be even more pedantic: G is not an "acceleration rate", "g" is.
 
That really helpfull. I sit in a better place now. Thanks for the wonderfull explanation.
 
omin said:
Where does 0.0000000000667 come from?

That is a good question. Why is G the value it is?

Maybe it is the only conceivable value possible that would lead to a stable Universe where thinking lifeforms could evolve and wonder why G was that value!

Maybe in other Universes it has a different value?
It is one of the least accurately measured constants - only 6 significant figures I think...
 
I have misled things unintentionally in my first quesiton.

Humans have chosen distance, mass and time constants. These constants are used to define G, 0.0000000000667.

Is there an accessable to the laymen way, and brief way, to step through how we use our constants to arrive at 0.0000000000667?
 
omin said:
Is there an accessable to the laymen way, and brief way, to step through how we use our constants to arrive at 0.0000000000667?
It is found by application of Newton's law of gravitation. Perhaps http://www.npl.washington.edu/eotwash/gconst.html will help.
 
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