Acceleration Due to Gravity
The uniform acceleration produced in a freely falling object due to the gravitational pull of the earth is known as acceleration due to gravity.
It is denoted by g and its unit is m / s 2. 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 / s 2 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 a is given by
g = Gm / R 2
where M = mass of the earth = 6.0 * 10 24 kg and R = radius of the earth = 6.38 * 10 6 m.
Acceleration due to gravity at a height h above the surface of the earth is given by
gh = Gm /( R + h) 2 = g( 1 – 2h / R)