## Free fall and Weightlessness

Subject: Science

#### Overview

Weightlessness is the situation of having zero weight of a body with certain mass. This note has brief explanation of free fall and weightlessness.

##### Free fall and Weightlessness

Freefall

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 freefall then a < 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 the moon:

One cannot land safely, because due to the absence of the 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:

If the reaction that makes us conscious of our weight, when we stand or walk, becomes zero due to some reasons, one will feel weightless.  Weightlessness is the condition in which the weight of the body seems to be zero. A body with a fixed mass will be weightless under the following conditions:

1. When a body falls freely under the influence of the force of gravity only.
2. When the acceleration of a falling body is equal to the acceleration due to gravity.
3. When a body is at the center of the earth or in the space at null point (g = 0 → w = mg = 0)
4. The body in the artificial satellite or rocket becomes weightless while orbiting around a heavenly body.
##### Things to remember
1. If an object is falling freely under the action of gravity along without any external resistance then the situation is called free fall.
2. If there is atmosphere, there is no free fall because of air resistance.
3. Freefall is the situation of having zero weight of a body with certain mass and acquired when a body is in free fall or there is no gravity.
4. Weightlessness of a body is the state in which the body experiences that the body is not being attracted by any force.
5. Weightlessness occurs during free fall and at the null point.
6. The space between any two heavenly bodies at which the resultant gravity is zero is said to be a null point.
7. In a falling parachute, when a weight of the parachute becomes equal to the air resistance, its acceleration is zero.
• It includes every relationship which established among the people.
• There can be more than one community in a society. Community smaller than society.
• It is a network of social relationships which cannot see or touched.
• common interests and common objectives are not necessary for society.