- All objects are attracted towards the earth by a force which is called The force of gravity.
- This force produces an acceleration which is called acceleration due to gravity and is denoted by 'g'.
- The value of 'g' on the surface of the earth is 9.8m/s^2.
- 'g' is an extremely important constituent of Physics and most of the Physics numerical problems involve the usage of 'g'.

### Effect of The Shape of Earth on 'g'

1)Earth isn't a proper sphere, it's a geoid ( flattened at the poles )

2) g = GM/Re^2

The radius of the earth is lesser at the poles than the equator

Therefore, the value of 'g' will be more at the poles, ( according to calculations, by 0.018m/s^2, it will be more )

###

Variation In 'g'

We take the magnitude of 'g as 9.8 in general, but the value of 'g' varies:-

1) IF THE OBJECT IS ABOVE THE SURFACE OF THE EARTH,

g(at h) = g(1+2h/Re)

2) IF THE OBJECT IS BELOW THE SURFACE OF EARTH ( AT DEPTH )

g(at d) = g(1+d/Re)

As a final note, we also have to remember that 'g varies at different celestial bodies as well

EG :- 'g' on the earth = 9.8m/s^2

'g' on the moon = 1.64m/s^2

- Aryan Awasthi

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