Question

Why gravitational force is more at poles and less at equator?

Answer 1

Gravitational field between two bodies, as expressed by Newtonian equation, is inversely proportional to square of distance between their centres of gravity i.e. the higher the distance between the bodies the lower the gravitational field. The Earth is not a perfect sphere and its radius varies at poles and the equator, the radius being more at the equator than at the poles. This means that a body at the equator is farther away from the earth’s centre than a body at the poles. Therefore, the gravitational field at the equator will be lesser than that at the poles
that is,
Sir Isaac newton discovered gravity and studied to give a formula : g=GM/r^2
What u r asking is the gravitational force i.e.
F=GMm = mg
r^2
M=mass of earth
m=mass of object
So, the gravitational force is inversely proportional to the spuare if the radius of the earth.
Since, our earth is not a perfect sphere it has a shape of ellipsoid that is, it bulges out at the equator.
That means the radius is slightly greater (about 21 km) at the equator as compared to the poles. Therefore due to the inverse relation , gravitational force at poles turns out to be 10m/s^2 and at equator 9.8 m/s^2.