Question

Why is the value of gravitational constant $6.67\times {10}^{-11}$?

Answer 1

G is the number expressing the proportionality between the attractive force exerted by two objects and the ratio of the product of their masses to the square of the distance between them (Newton’s law of universal gravitation). It is the universal gravitational constant which was calculated by Henry Cavendish in 1798. He followed a method prescribed and used apparatus built by his countryman, the geologist John Michell, who had died in 1793. The apparatus employed was a torsion balance, essentially a stretched wire supporting spherical weights. The attraction between pairs of weights caused the wire to twist slightly. The experiment was popularly known as weighing the Earth because the determination of G permitted calculation of the Earth’s mass.