## TyroCity

Physics XI Notes for Physics Notes

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# Variation Of g -variation Of Acceleration Due To Gravity

Variation of g-variation of acceleration due to gravity

We know that the force of gravity varies from place to place on the surface of earth.
There are two reasons behind this variation:

• The shape of earth.
• The rotation of earth.

The earth is not a perfect sphere, but bulges at the equator. Therefore, if a body is taken from pole to the equator its distance from the centre of the earth will change. Consequently, the gravitational force also varies.

Variation of g with altitude

Consider the variation of g when a body moves distance upward or downward from the surface of earth.
Let g be the value of acceleration due to gravity at the surface of earth and g’ at a height h above the surface of earth.
If the earth is considered as a sphere of homogeneous composition, then g at any point on the surface of the earth is given by:

This expression indicates that the acceleration due to gravity decreases with altitude.