Question

write any three differences between the acceleration due to gravity (g) and universal gravitational constant (G)

Answer 1

Universal gravitational constant(G) : All the objects that exist in universe attract other objects. The attractive force that exists between any two objects(say A and B, as in picture below) is directly proportional to the product of their masses and inversely proportional to the square of distance between their center(center of gravity or centroid). The value of G was obtained by sensitive balance in laboratory, firstly by Cavendish.

Acceleration due to gravity(g) : Whenever we drop something we observe the thing falls towards the center of the earth. The force that enables this movement is indeed the one that’s shown above. Here, object A(say), having mass M, is the earth and object B, having mass m, is the body being dropped. From Newton’s second law of motion it can be written,

Force = Mass X Acceleration,

now the force(F) on body B that’s dropped is

F = m X a ,

where say ‘a’ is the acceleration with which it’s falling,

when we equate these two forces we get, (if the body B is near the surface of the earth, then distance can be considered equal to radius of the earth i.e. R)

so, the acceleration a here is nothing but the acceleration due to gravity i.e. g.

Answer 2

$\huge\mathfrak{Gravitational\:constant(G)}$

• its value remain constant always and everywhere.

• its unit is N${m}^{2}$${kg}^{-2}$.

• It is a scaler quantity.

$\huge\mathfrak{Acceleration\:due\:to\:gravity\:(g)}$

• It value varies at various places.

• Its unit is ${ms}^{-2}$

• It is a vector quantity.