Free fall

If an object is falling freely under the action of gravity alone without any external resistance then the situation is called free fall.

During free fall an object falls with the acceleration which is equal to the acceleration due to gravity of that planet or satellite.

i.e. Acceleration of falling body = acceleration due to gravity during free fall. a = g

But if there is air resistance the situation of free fall does not arise. Thus, if there is no free fall thena < g

Examples of free fall

1. The fall of an object on the moon where there is no air resistance
2. The fall of an object in the space where there is no effect of gravity.

The paratroopers land safely on the ground with the help of parachute:

It is because no free fall takes place if a person is falling with the help of a parachute. The parachute will increase the air resistance. Due to this, the acceleration of the falling parachute becomes less than the value of acceleration due to gravity. As a result, he or she could safely land on the ground.

In case of moon:

One cannot land safely, because due to the absence of atmosphere (air resistance). Hence, the parachute will fall freely on the moon. There is a high chance of getting hurt.

The probability of getting hurt is more when one falls from the significant height because:

The ground striking velocity while falling from a significant height will be more and, therefore, the effect of force also will be more. It is because momentum (M) will be more since,

Momentum = Mass x Final Velocity.

i.e. p = m x V

Weightlessness:

It is the situation of having zero weight of a body with certain mass.

Conditions required for weightlessness.

Following are the condition required for weightlessness:-

1. The object should be in free fall i.e. a = g.
2. The object is beyond the gravitation field i. e. g = 0.

Factors Affecting:Acceleration due to gravity.

Gravitation field intensity.

1. The factors affecting acceleration due to gravity are as follow:-

   Since,

   g=

   Therefore, the affecting factors are:-

   Mass of the planet or satellite i.e. F∝ M

   Radius of the related body i.e F ∝

2. The factors affecting gravitation field intensity are as follow:-

   Since,

   I =

   Therefore, the affecting factors are:-

   Mass of the planet or satellite i.e. I∝ M

   Radius of relation body i.e. I ∝