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# Weightlessness

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## Introduction

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Weightlessness is the absence of sensation of the weight. The weight of an object is defined as the product of the mass and acceleration due to gravity. While studying gravitation we come across many interesting facts about the effects of gravity, one among them is zero gravity or weightlessness. We know that the weight of an object is the force with which the earth attracts the object. When a person standing on the surface of the earth he/she will be experiencing the weight, earth will exert a force equal and opposite to the weight of the person. In this article, we will come across a detailed understanding of the weight and weightlessness of the object.

## What is Weightlessness:

To understand what is weightlessness we must begin with the effects of gravity and the concept of weight. From the definition of weight, we know that weight is directly proportional to the mass of the object. As the mass of the object increases the weight of the object will also increase. Now, the question that arose after the definition of weight, what is weightlessness?Â

Weightlessness is encountered when the object undergoes free fall. When a person standing on the surface of the earth he/she will be experiencing the weight, earth will exert a force equal and opposite to the weight of the person to keep him at rest. The same principle holds good for when we measure the weight of an object by spring balance hung from a fixed balance. The object will fall unless there is an external force acting on it in the opposite direction of gravity. Now, let us imagine both ends of the spring balance are free, both springs will move concerning acceleration due to gravity, then the object will feel zero gravity. This phenomenon of freefall is known as weightlessness.

Now, let us have a look at the weightlessness definition. So, weightlessness is the phenomenon of zero gravity when an object or a person experiences freefall. In other words, Weightlessness is a condition experienced while in free fall, in which the effect of gravity is cancelled by the inertial (for example, centrifugal force) force resulting from the orbital flight. It is also known as zero gravity and it is often used to describe such a condition i.e., Freefall, where the only acceleration offered is the acceleration due to gravity.

### Weightlessness in Space:

Astronauts orbiting in space feel a way of weightlessness because there's no external contact force in space pushing or pulling upon their bodies. Gravity is the only force acting upon their body. Gravity being an action-at-a-distance force can't be felt and thus wouldn't provide any sensation of weight. Thus astronauts feel weightlessness in space.

Crews of spacecraft are subject to the issues of weightlessness. It was learned from early Soviet and U.S. manned missions that there's a decrease in heart and respiration rates and a progressive loss of weight and bone calcium during flights of relatively short duration. A reversal of most of those effects occurs, however, upon return to Earth. On later missions of extended duration, like those involving the U.S. Skylab and Soviet Salyut space stations, extensive biomedical studies were undertaken.

The sensation of weightlessness, or zero gravity, happens when the effects of gravity are not felt but can be experienced. In general, gravity does exist everywhere in the universe because it is defined as the force that attracts two bodies to each other. But astronauts in space usually don't feel its effects.

The ISS (International Space Station), for example, is in perpetual freefall above the Earth. Its progress, however, almost equals the speed of its fall toward the earth. This means that the astronauts inside aren't pulled in any particular direction. So they float.

Not having in touch weight on your feet sounds relaxing, but within the future, there are many health problems related to it. Bones and muscles weaken, and other changes also happen within the body. One of the functions of the ISS is to study how astronaut health is affected by long periods of weightlessness.

### Examples of Weightlessness:

Let us have a look at some examples of weightlessness. Other than the falling from the top, objects attached to a spring with free ends, etc.. other than these there are many examples that elaborate weightlessness.

1. Astronauts in the spaceship will experience weightlessness almost, we witness them floating due to zero gravity.

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2. People using elevators will experience weightlessness or zero gravity. The weightlessness experienced in the elevators is known as effective weightlessness. This is the best explanation for the weightlessness that elaborates weightlessness doesnâ€™t mean the absence of gravity but it means the absence of sensation of the gravity or weight of the object. Also, this can explain that mass and weight arenâ€™t the same factors, though a person is feeling weightless that doesnâ€™t mean they are massless.

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### Did You Know:

Weightlessness doesnâ€™t make people weightless. People arenâ€™t weightless on the ISS (International Space Station). 90% of the Earthâ€™s gravity still affects the ISS (International Space Station), so people weigh 90% of what they would on Earth. The reason the astronauts float is that the ISS is in perpetual free-fall around the Earth, an orbit in which microgravity takes effect because the people and objects inside fall at the same rate as the ISS itself.

FAQ (Frequently Asked Questions)

1. What is Weightlessness in Physics?

Ans: Weightlessness is a condition experienced while in free fall, in which the effect of gravity is cancelled by the inertial (for example, centrifugal force) force resulting from the orbital flight. Therefore, weightlessness in physics is the absence of the sensation of weight.

2. Is Weightlessness Implied in the Absence of Gravity?

Ans: No. weightlessness is the zero gravity or when we say it canâ€™t be felt. Weightlessness explains the absence of sensation of weight, it is often known as zero gravity because it is against the gravitational force.