Question

define acceleration due to gravity and derive relationship between g and G? ​

Answer 1

Answer:

The acceleration on an object due to the gravity of any massive body is represented by g (small g). The force of attraction between any two unit masses separated by unit distance is called universal gravitational constant denoted by G (capital G). The relation between G and g is not proportional

Answer 2

Answer

Relation between Acceleration due to Gravity (g) and Universal Gravitational Constant (G) 

The acceleration produced by the gravitational force of the Earth is called acceleration due to gravity (g)

" The acceleration gained by an object freely falling the Earth because of gravitational force is called acceleration due to gravity".

It is represented by 'g'. This value is independent of the shape and mass of the body. Its S.I unit is m/s2.

Suppose, that the Earth's radius is R and its mass is M. The value of the gravitational force acting on a particle of mass 'm' at a distance 'r' from the center.

F=r2GMm  (1)

By Newton's second law of motion

F=ma 

∴ If the acceleration due to gravity is g at point P

F=mg  (2) 

From the equation (1) and (2) we get 

∴ mg=r2GMm 

or g=r2GM (3)

∵ r=(R+h) 

 

          g=(R+h)2GM  (3) 

where ' h' is the height of the particle above the Earth's surface. If point P is close to the surface of the Earth then the value of h will be negligible with reference to the radius R of the Earth , i.e., 

h<<R 

∴h+R≈R 

From the equation (3) 

∴ g=R2GM  (4) 

If Earth's average density is ρ then;

Mass of the Earth , M = Volume × Density 

M=34πR3ρ

From the equation (4) 

g=R2G34πR3ρ 

or g=34πGRρ  (5) 

This equation (5) shows the relationship between (g) and density (ρ).