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LESSON NOTES

What is Free Fall?

 Due to gravitational force Earth attracts every object towards it.

 So, whenever an object falls towards earth it falls under the influence of
gravitational force and if only gravitational force acts on the object during its

free fall then such a motion of object is said to be free fall motion

 When an object falls freely towards the earth there happens to be no change
in the direction of motion of the object but due to the attraction of earth there
will be a change in the magnitude of velocity.

 Change in velocity involves acceleration. So, whenever the objects falls

towards earth an acceleration is involved due to earth's gravitational force.
 Free fall is defined as a situation when a body is moving only under the

influence of earth’s gravity.

Acceleration due to gravity:

 The acceleration produced in a freely falling body is called as acceleration
due to gravity.

 Symbol of acceleration due to gravity is g.

 S.I unit is m/s .
2

 The value on the Earth’s surface is 9.8m/s .
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RELATION BETWEEN G AND g

Let us find the value acceleration due to gravity during free fall. To find this we take

one assumption that the height from which the ball is dropped is very small as
compared to the radius of the earth.

F = GMm/R ———– (1)
2
According to Newton’s second law,