Question

what is gravitational constant and how it's value was obtained​

Answer 1

Gravitational Constant

“Big” G is Newton’s gravitational constant and gives the constant of proportionality in Newton’s Universal law of gravitation which is the basis of our understanding of non-relativistic gravity. The gravitational force F between two bodies of mass m1 and m2 at a distance R is:

$ F = {{G m_1 m_2}\over{R^2}} $

In SI units, G has the value 6.67 × 10-11 Newtons kg-2 m2.

The direction of the force is in a straight line between the two bodies and is attractive.

• Thus, an apple falls from a tree because it feels the gravitational force of the Earth and is therefore subject to “gravity”. The acceleration g=F/m1 due to gravity on the Earth can be calculated by substituting the mass and radii of the Earth into the above equation and hence g= 9.81 m s-2.

$\huge \mathbb \red {HOPE \: THIS \: WILL \:}$

$\huge \mathbb \red {HELP \: YOU \:}$

☺

Answer 2

$\huge{ \colorbox{yellow}{ \color{black}{Answer}}}$

Simple Definition:

• In Newton's law of universal gravitation, the attractive force between two objects (F) is equal to G times the product of their masses (m1m2) divided by the square of the distance between them (r²)

How it was obtained:

• The first direct measurement of gravitational attraction between two bodies in the laboratory was performed in 1798, seventy-one years after Newton's death, by Henry Cavendish. He determined a value for G implicitly, using a torsion balance invented by the geologist Rev. John Michell (1753).

Formula:

$\huge \tt \boxed{G = \frac{m_{1}m_{2}}{ {r}^{2} } }$

Value:

$\huge \tt \boxed{6.67×{10}^{-11}Nm²{Kg}^{-2}}$