Freefall
•    When an object falls down towards the earth under the gravitational force alone, we say the object is in free fall.
•    The velocity of a freely falling body changes and is said to be accelerated.
•    This acceleration is called acceleration due to gravity, denoted by ’g’. Unit is m/s2.
•    The motion of objects under the influence of gravity ‘g’ does not depend on the mass of the body. All objects fall at the same rate.
We know that, F= ma
Therefore, F = mg
The force (F) of gravitational attraction on a body of mass m due to earth of mass M and radius R is given by

 

 

g.    But the acceleration due to gravity is represented by the symbol g. Therefore, we can write
h.    F = mg               ... (2)
i.    From the equation (1) and (2), we get

 

 

j.    When body is at a distance ‘r’ from the centre of the earth then

 

 

 

 

 

 

 

 

 

Weight of object on the moon
Just like the Earth, the Moon also exerts a force upon objects. Hence, objects on moon also have some weight. The weight will not be same as than on the earth. So, weight on the Moon can be calculated as -