Identify reasons for possible variations from the value of 9.80665 m/s2

The value for the gravitational acceleration on Earth's surface mainly have to do with geographical location. The factors that cause these are:

**Composition and structure of the ground**- The composition of the Earth's lithosphere is not constant.
- As greater mass creates a stronger gravitational field, the gravitational force would be STRONGER where the soil is DENSER.

**The shape of the planet.**- The Earth is NOT a perfect sphere, rather it is an ELLIPSOID.
- It is flatter at the poles and bulged out at the equator.
- As gravitational force is affected by distance ($F_g = \frac{GMm}{r^2}$) the CLOSER one is to the Earth the STRONGER the gravitational force.
- Thus, gravitational acceleration is:
**GREATER**($9.83ms^{-2}$) at the**POLES**- LESSER ($9.78ms^{-2}$) at the EQUATOR

**Earth's rotation**- The spin of the Earth can
**reduce**the effective gravitational force due to a**centrifuge effect**as some of the weight force actually provides the centripetal force for the Earth to rotate. - As the Earth effectly doesn't spin at the poles and spins the fastest at the equator, gravitational acceleration is:
**GREATER**($9.83ms^{-2}$) at the**POLES**- LESSER ($9.78ms^{-2}$) at the EQUATOR

- The spin of the Earth can
**Altitude**- As said before, the distance from the centre of mass effects the gravitational force and subsequently the gravitational acceleration at that point.
- From that, Altitude will obviously affect the gravitational acceleration in some way.
- A body that is x metres above the planet will undergo the gravitational acceleration of $g = \frac{GM}{(r+h)^2}$ (This is talked about in the next dot point.)
- Thus, the HIGHER the altitude, the LESSER the gravitational acceleration.

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