Earth’s gravitational acceleration :
- The earth exerts gravitational force on objects near it.
- According to Newton’s second law of motion, a force acting on a body results in its acceleration.
- Thus, the gravitational force due to the earth on a body results in its acceleration. This is called acceleration due to gravity and is denoted by ‘g’.
- Acceleration is a vector.
- As the gravitational force on any object due to the earth is directed towards the centre of the earth, Direction of the acceleration due to grav-ity is also directed towards the centre of the earth i.e. vertically downwards.
- Value of g on the surface of the earth :
F= GMm/r²
F=mg
∴ mg = GMm/r²
∴ g = GM/r²
The mass and radius of the earth are 6 x10²⁴ kg and 6.4x10⁶ m, respectively.
- This acceleration depends only on the mass M and radius R of the earth.
- Acceleration due to gravity at a given point on the earth is the same for all objects.
- It does not depend on the properties of the object.