Page 62 - Force 10

Variation of acceleration due to gravity:

(a) Due to shape of the earth: From the relation between g and G, we have

g =

2

This gives the acceleration due to gravity on the surface of the Earth. The shape of the Earth is not

perfectly spherical. It is bulged at equator and flattened at poles. Its equatorial radius ( ) is more than

polar radius ( ), (nearly 21km equatorial radius is more than polar radius).

At equator, = 2 Let us suppose = 3 and

= 2

At poles, = 4

2 =
9

Or, 9 = 4

2
Therefore, =
2

Since, >

So, >

Thus , acceleration due to gravity on the poles is greater than that on the equator

and correspondingly, weight of a body is more at poles than at equator.