- Books Name
- Science Made Easy Science Book
- Science Made Easy
- CBSE Class 9
Gravitational Acceleration and its value at the surface of earth
→ The uniform acceleration produced in a freely falling object due to the gravitational force of
earth, is called acceleration due to gravity.
→ It is represented by ‘g’ and it always acts towards the centre of the earth.
Mathematical Expression for g
From the second law of motion, force is the product of mass and acceleration.
F = ma
For free fall, acceleration is replaced by acceleration due to gravity.
Therefore, force becomes:
F = mg ….(i)
But from Universal Law of Gravitation,
Factors Affecting the Value of g
- As the radius of the earth increases from the poles to the equator, the value of g becomes greater at the poles than at the equator.
- As we go at large heights, value of g decreases.
To Calculate the Value of g
Value of universal gravitational constant, G = 6.7 × 10–11 N m2/ kg2,
Mass of the earth, M = 6 × 1024 kg, and
Radius of the earth, R = 6.4 × 106 m
Putting all these values in equation (iii), we get:
Thus, the value of acceleration due to gravity of the earth, g = 9.8 m/s2.