Weightlessness

Introduction:

Weightlessness is an essential concept of physics in class 11th. Many critical physics applications are based on it, and hence it is a point of concern. The relation of weightlessness with gravity and Otis L Evaderz’s elevator experiment further helps understand it correctly. Let us learn all about this concept, including some prominent examples.

Weightlessness: Definition

The sensation of complete or new complete absence of weight is defined as weightlessness. Astronauts orbiting the earth in space feel this sensation. These are similar to the sensations felt by a person sitting on any ride in the amusement park.

There is no external contact force in space pushing or pulling the bodies, and hence astronauts feel the same. Gravity is the only force counteracting the object. When in space, this force of contact is acting at a considerable distance, and hence it can’t be felt on the body. Thus, the astronauts feel weightless in space.

The studies from early Soviet and the US manned missions indicated a decrease in heart and respiration rate along with weightless astronauts in space. It also hints at the loss of bone calcium, especially in short-duration flights. For missions involving astronauts in the long-term, detailed studies were conducted by the Soviet Salyut space and the US Skylab.

It is surprising to note that gravity exists everywhere globally as it is the force of attraction. Thus, it is also present in space, but only due to the different conditions its effects are nullified, making astronauts feel weightless.

Further, the International Space Station is in freefall above the earth. Astronauts float, and they’re not pulled in any direction as the speed of their movement matches the freefall.

Reasons for weightlessness:

Weightlessness is the sensation experienced by a person or an object when no external forces touch one’s body. This sensation is observed when all the contact forces are removed from the person or object. It is a familiar sensation to the state of free fall. When a body falls freely, the only force acting on it is the force of gravity. Further, it is hard to feel gravity without any opposing force. This is the main reason for feeling weightless.

After going through its reasons, it becomes clear that weightlessness is only a sensation but not an actual condition. Thus, it can be drawn that it has nothing to do with the body weight or the person/ object losing weight.

Examples of weightlessness:

Some of its common examples include:

• We feel astronauts floating as they experience weightlessness due to zero gravity in space
• People using elevators feel the sensation of the absence of gravity or body weight even in the presence of gravity, the weightlessness felt is called effective weightlessness

Otis L Evaderz’s elevator experiment:

The famous physicist Otis L Evaderz has conducted an elevator experiment that involves a person riding up and down the elevator while standing on the bathroom scale. It is important to note that a bathroom scale doesn’t measure the body’s weight. It gives the reading of the measure of the upward force applied by the scale to balance the downward force of gravity acting on the person standing on the scale. A body is thus said to be in equilibrium when these forces equal each other. The amount of the upward force that balances the force of gravity equals the object’s weight.

When a person moves up and down on the scale, the scale reading quickly changes as the person accelerates. The changing body weight is thus due to the upward balancing force of the scale. Hence, it only means that the weight is not changing but the counter-acting force changes due to the body’s movement.

Otis L Evaderz observed that while going up and down on a bathroom scale, the scale’s reading was different while accelerating up and down in the elevator. The same was also different when the person was at rest or travelling constantly. Hence, it becomes easy to measure this normal upward force that can be predicted during different motion stages. Further, Newton’s second law of motion and acceleration value helps calculate the normal force acting on Otis’s 80-kg body.

The normal force on the person is greater than the force of gravity when the person is accelerating upwards and is less than when the person is on downward acceleration.

Conclusion: 

It is easy to understand the definition of weightlessness with the help of the best examples. Some of the top reasons for weightlessness include balancing the bodyweight with the gravitational forces. Also called zero gravity, it can be simply understood with the observations from Otis L Evaderz’s elevator experiment. The difference between the force of gravity on earth and space further makes it easy to understand this phenomenon.