Universal Gravitation
Universal Gravitation Constant
G in the expression that shows the law of universal gravitation is an universal gravitation constant.
The value of the universal gravitation constant is "6.672x10-11Nm2kg-2".
In view of the index of the 11th minus power, it is understood that the value of gravitation is minute.
Obtaining the value of G after the age of Newton became a problem.
It is Henry Cavendish taht decided universal gravitation constant G by the experiment.
At that time, gravitational acceleration g and radius of the earth r have already been known.
Therefore, if the value of G is obtained, mass of the earth M can be calculated from the relation of GM/r2=g.
This experiment by Cavendish was criticized , saying that "Experiment that decided the mass of the earth".