: distanCC( apat.

gravitational

strength.

Gravity is the special case

gravitation. If one body

is the earth, then th

attractiob

between the earth an

3.

he force of attractjon between any two

bodies is called 'gravitation.' Its

constant is denoted by "G".

force of

any other material objec

is called "gravity." Th

acceleration of the bod

produced by this force

denoted by 'g'.

Its dimensions are L' MT,

Its SI unit is Nm'kg.

It is a universal constant. It has the 6. It is a local constant. Its value

4

Its dimensions are LT

5.

Its SI unit in ms

same value for all pairs of

bodies. Its value is 6.67x 10

N.m kg,

constant.

Its value

changes from place

place. Its average value

on the surface of the

earth is 9.8ms4.

of

It is n: Anse Mass of the earh can be desermined by using Newtoms law of graviation

Assumptis

The earthisa perfect sphere

2 The eurth possesses hocmogenecus coposiion

Qantitative Descriptiom:

Coesider an object of mass M placed near (or om) the surface of he eanh

Suppose beight of the objet from the base to its CG =

Let mss of the earth

Let radis of the earth

Let distance of the object from its CG. to the cemter of the earth = Re+t= Re

The gravitational force of atraction iof an object towards the cemner of the eah s

given by the law of gravitation:

M

=ReF GMM(1)

R

But the force with which the earth attracts a body towards its cenre is called

eight.

m

=W F Mg

mparing eq. (1) and 2, we have

F2)RMg =GM

)

Earthof the Earth:

Fig &.4

ss multiplication, GMRM=

ing the values in RH.S., we can compute mass of the earth

ons:

6.37 x 10m. So.

9.8 ms x(637 x 10m

667 v 10