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Note on Free fall

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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 ∝

  • If an object is falling freely under the action of gravity along without any external resistance then the situation is called free fall.
  • If there is atmosphere, there is no free fall because of air resistance.
  • Free fall is the situation of having zero weight of a body with certain mass and acquired when body is in free fall or there is no gravity.
.

Very Short Questions

When there is no air resistance, a coin and a feather fall together. Acceleration of the feather and a coin at that instant is 9.8 m/s2. All objects fall towards the earth"s surface with the same acceleration despite the difference in masses if air resistance is not there. In reality, the objects with greater mass fall faster because they experience less air resistance. But, as the coin and feather do not experience any air resistance they have the same acceleration.

The free fall is defined as the falling of an object in absence of any external resistance with acceleration equal to the acceleration due to gravity.

Weightlessness is a condition when any object falls freely under the action of gravity experiencing no weight of its own.

On the earth the parachute at first falls with higher speed. But after certain time the upthrust of the earth and its downward force balance eachother. Due to balance forces it attains a constant velocity. But on the moon there is no atmosphere. Therefore, parachute falls down with acceleration due to gravity on the moon.

Air is always present in real life due to the obstruction of air objects do not fall freely.

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  •  Free fall does not takes place if a person is falling with the help of parachute, because it will ______.

     not change the air resistance 


    decrease the air resistance 


    increase the air resistance 


    none of the answers are correct 


  • 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  the effect of force also will be less 


    The ground striking velocity while falling from a significant height will be less and therefore the effect of force also will be less


    The ground striking velocity while falling from a significant height will be less and therefore the effect of force also will be more


    The ground striking velocity while falling from a significant height will be more and therefore the effect of force a will also be more


  • Which of the following is the condition required for free fall?

    There should be no gravity, if the body is at earth's center or at null point. 
    The acceleration of a falling body should not be equal to the acceleration due to gravity.
    The object should not be beyond the gravitation field

    The object should not be in free fall

  • Why it is not safe to use parachute on the moon?

    Because due to absence of gravity, parachute will fall-freely on the moon. There is high change of getting hurt.
     Because due to absence of air resistance, parachute will fall-freely on the moon and there  is high chance of getting hurt.
    None of above 
    Because the ground striking velocity while falling from a significant height will be more and therefore the effect of force also will be more.
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Difference between freefall and weightlessness


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