# Acceleration Due to Gravity | Definition, Formula, Units – Gravitation

Acceleration Due to Gravity Definition:
The uniform acceleration produced in a freely falling object due to the gravitational pull of the earth is known as acceleration Due to Gravity.

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## Acceleration Due to Gravity | Definition, Formula, Units – Gravitation

Acceleration Due to Gravity Denoted by:
It is denoted by g.

Acceleration Due to Gravity Units:
SI unit is m/s²

It is a vector quantity and its direction is towards the centre of the earth.

The value of g is independent of the mass of the object which is falling freely under gravity.

The value of g changes slightly from place to place. The value of g is taken to be 9.8 m/s² for all practical purposes. The value of acceleration due to gravity on the moon is about one sixth of that on the earth and on the sun is about 27 times of that on the earth.

Among the planets, the acceleration due to gravity is minimum on the mercury.

Relation between g and G is given by, g = $$\frac{G M}{R^{2}}$$

where, M = mass of the earth = 6.4 x 1024 kg
and R = radius of the earth = 6.38 x 106 m.

Gravitational mass Mg is defined by Newton’s law of gravitation.
Mg = $$\frac{\mathrm{F}_{\mathrm{g}}}{\mathrm{g}}=\frac{\mathrm{w}}{\mathrm{g}}=\frac{\text { Weight of body }}{\text { Acceleration due to gravity }}$$
∴ $$\frac{\left(M_{1}\right)_{\mathrm{g}}}{\left(M_{2}\right)_{g}}=\frac{F g_{1} g_{2}}{F g_{2} g_{1}}$$
Inertial mass (= Force/Acceleration) and gravitational mass are equal to each other in magnitude.

Inertial Mass and Gravitational Mass
(a) Inertial Mass = $$\frac{\text { Force }}{\text { Acceleration }}$$
(b) Gravitational mass = $$\frac{\text { Weight of body }}{\text { Acceleration due to gravity }}$$
(c) They are equal to each other in magnitude.
(d) Gravitational mass of a body is affected by the presence of other bodies near it. Inertial mass of a body remains unaffected by the presence of other bodies near it.

Gravitation:
Have you ever thought, when we throw a ball above the ground level, why it returns back to the ground. It’s because of gravity. When a ball is thrown above the ground in the opposite direction, a gravitational force acts on it which pulls it downwards and makes it fall. This phenomena is called gravitation.

Learn relation between gravitational field and potential field, Kepler’s law of planetary, weightlessness of objects in absence of gravitation, etc.