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# Weightlessness

• Last Updated : 21 Jul, 2021

The sensation of being completely or nearly completely weightless is referred to as weightlessness. Weightlessness is a common feeling for astronauts circling the Earth. The feelings felt by orbiting astronauts are similar to those felt by anyone who has been suspended above a seat on an amusement park ride for a short period of time. In each of these circumstances, the reasons for the sense of weightlessness are the same.

### What is Weightlessness?

Weightlessness is a terminology used to express the experience of being completely or nearly completely weightless. Weightlessness is a common sensation for astronauts in orbit around the Earth. These feelings felt by the astronauts in orbit are similar to those felt by anyone who has been momentarily suspended above the seat on an amusement park ride.

When your body is in free fall and the acceleration is downward at gravity, you are said to be weightless. The term “zero gravity” can be used to describe this state. When there is no support of force on our bodies, we are said to be weightless.

### Why do we feel weightless?

Weightlessness occurs when the gravitational pull is zero. We feel weight because, after our body produces a force on the ground owing to gravitational attraction, the earth exerts an equal and opposite force on our body. When falling freely under g, there is no solid object that can impose a force on us, giving us the sensation of being weightless.

A person experiencing weightlessness feels as if no exterior items are touching his or her body. In other words, when all contact forces are gone, the experience of weightlessness exists. The sensations described above are frequent in free fall. The force of gravity is the sole force acting on the body during free fall. Gravity cannot be sensed without an opposing force since it is a non-contact force. When you’re in free fall, you’ll feel weightless because of this.

It’s vital to understand that weightlessness is only a sense, not a reality associated with someone who has lost weight. Weightlessness is more about the presence and absence of contact forces than it is about weight.

### Why do Astronauts Feel weightless in Space?

Since there is no external contact force pushing or tugging on astronauts in space, they experience a sensation of weightlessness. The only force exerted on their body is gravity. Gravity is an action-at-a-distance force that can’t be felt, thus it can’t give you a sense of weight.

Many pupils believe that astronauts experience weightlessness because there is no gravitational pull in space. This isn’t correct. If this were true, the circular motion principles would be violated. If one believes that the absence of gravity in space is the cause of weightlessness, then why are people orbiting in space?

### Is the Gravity in Space lesser than the Gravity on Earth?

The force of gravity operating on an astronaut in space is unquestionably smaller than that acting on surface of the Earth. However, it is not modest enough to account for a significant weight loss. If space station is orbiting at height of 800 km above the Earth’s surface, the value of g will be lowered from 9.8 m/s2 to around 7.35 m/s2 at that position.

While it does help astronauts lose weight, it doesn’t account for the feeling of being completely weightless. Because they are free-falling towards the Earth, they feel completely weightless due to lack of a surface to support them.

### Ways to avoid weightlessness

Weightlessness contrasts with contemporary human experiences that involve a non-uniform force, such as:

• When a vehicle decelerates due to atmospheric drag during reentry or the use of a parachute,
• Sitting on a chair on the ground, standing on the ground and other activities where gravity is counteract by the ground’s support force,
• While a spacecraft is performing an orbital manipulated or when rocket engines are providing thrust during the launch phase,
• Flying in a plane, when the lift created by the wings produces a support force.

When an item is not weightless, as in the examples above, a force operates on the item in a non-uniform manner. Drag, aerodynamic lift and thrust are all non-uniform forces that operate on a point or surface rather than acting on an object’s total mass, resulting in the weight phenomenon. This non-uniform force can also be transferred to an item when it comes into touch with another item, such as when one’s feet come into touch with the Earth’s surface or when a parachute harness comes into touch with one’s body.

### Sample Problems

Problem 1: Why do we feel weightlessness in a space?

A person might feel weightlessness in space as there is nothing to oppose the force of gravity. Since, there is ground or normal force to be opposed for, so the person feels weightlessness.

Problem 2: Is it really zero gravity in space?

Some individuals believe that space has no gravity. In truth, there is a minor amount of gravity everywhere in space. The moon is held in orbit around Earth by gravity. Gravity, on the other hand, weakens with distance.

Problem 3: Imagine swinging back and forth on a swing on a swing set. When do you feel “weightless?”

Only when you have a net zero force will you feel weightless.

You must not be speeding despite the fact that you are moving. You’re catapulted up at the top of the swing, and you’ll experience a net zero force owing to your upward momentum, which is equivalent to gravitational force but in the opposite (upward) direction. This situation happens when you are still in the air, i.e. at the top of the swing.

Problem 4: Is the gravity smaller or greater in space than gravity on the Earth?