Good day to you. Thanks for visiting my last post and for upvoting it.
It's nice having you here again to read my post which will focus on the physical phenomenon "Weightlessness"; the reason while you feel a weight loss when you descend in an elevator and to clear some misconceptions about the topic to be considered.
Hope you find this post interesting
My experience
My last experience of weightlessness brought me a little fortune while a pretty lady hugged me for like a minute in an elevator. It was a great moment but I pity myself if my wife had been there. lol. She can be jealous sometimes. The observation I made from the short incidence and the kind of shoe the lady wore inspired me to write this post. If you really want to know what brought about the hug, I think you need to read this post and learn the lesson thereof.
During the cause of the weekend, I visited one of the gigantic hotels in Abuja for an official meetup. After the meeting, I am to descend to the last floor of the building from the fifteenth floor. I entered into an elevator, followed by a lady, we slightly exchange greetings, I guess she is also off to the last floor, I pressed a button to take us to the last floor. As the elevator moved, the lady grabbed me on the suit, trying to use me as a support. Knowing well that the lady had lost her balance, I had to grab her by the waist, she also left my suit and grabbed my waist.
During the grab, it came to my mind the reasons why the lady lost her balance. First, it was due to the kind of shoe she wore. The lady wore a pointed heeled shoe of like 7 inches long. The shoe lacked enough friction due to its small surface area in contact with the floor of the elevator. From my basic knowledge of physics, for a body to be stable, four forces must come into play; the weight of the body (downward force) due to the effect of gravity on the body mass, the upward force (normal force), the forward force and the backward force due to friction. The second reason was due to the physical phenomenon called weightlessness.
Image created by me
Therefore I will be discussing the importance of friction to our body stability and the reasons for weightlessness concurrently.
What make you feel weight loss, force of gravity or normal force(contact force)?
Many people will describe weightlessness as loss of weight or lack of weight. It can also be described as loss of the influence of the gravity on a body. These definitions came into play because weight (in Newton) of a body is achieved due to the effect of gravity on the mass (in kg) of that body, or a force (F) on an object due to the influence of gravity (g) between it and the earth. i.e W = mg. The equation shows that the more reduced the effect of gravity on a body, the more reduced the weight of the body because the two parameters (W and g) are directly proportional to each other. On this note, many people will therefore conclude that a body is considered weightless if the gravity on the body is zero. But my question to you is that can the gravity of a body on earth be equal to zero. Soon you will get answer to this question and I will also show to you if the presumed definitions of weightlessness as defined by many are correct or not.
Okay. lets analyze the forces on a body in an elevator so that we can really understand what we feel in an elevator.
The image below shows the forces at play when an elevator is at rest (not in motion). There two forces involved; weight of the man standing on the elevator floor denoted by mg (a downward force) and the upward force known as the normal force (a contact force) denoted by N. A normal force is an upward force from the surface of the elevator floor, it is the actual force that makes us feel our weight, we are always in contact with it. If the normal force is not there, we will not be able to stand on the floor, we will just be like a free falling body. It can be simply put that the more the force I feel from the elevator floor the heavier I am. The normal force is influenced by the magnitude and the direction of movement of the elevator. The net force on the body is N-mg
Image created by me
When an elevator ascends with a certain force F = ma
Lets see what happens when an elevator ascends with a certain force F = ma. "m" is mass and "a" is the acceleration at which the elevator moves. The image below shows the forces acting on a body in an ascending elevator. The force at which the elevator ascends is positive because its moving upward (a positive direction).
Image created by me
When an elevator descends with a certain force F = ma
The image below shows the forces acting on a body in a descending elevator. The force at which the elevator descends will take negative sign because it moves in a downward direction.
Image created by me
To maintain stability in an elevator, it is important to maintain a high frictional force (usually created between the sole of your shoe and the floor of the elevated). This force ensures to balance with the forward force incase there is a little slide when the elevator is about to move. The image below show all the four forces that must be balanced before a body is considered stable. It is not advisable to wear a pointed heeled shoe is an elevator. Our young ladies should take note.
Conclusion
There was a misconception that for a body to feels a loss of weight (weightlessness), the gravitational force on the body is zero. I was able to clear the misconception that the normal force acting on a body is liable for the feeling of weight and not gravity because, a gravitational force is categorized as a force acting at a distance which can not be felt, but the normal force can be felt because it is a contact force. Though, the fact is that weight is a force experienced by a body of mass (m) under the influence of gravity. Weightlessness is simply described as the feeling of total loss in weight due to the effect of loss of normal force from a supporting material (contact made with the floor of an elevator).
Conclusively, the force of gravity on a body on earth can never be equal to zero, therefore its effect couldn't have resulted in a complete loss of weight of an object. Click here to read more. Note that it's not only in an elevator we can feel weight loss, it can also happen in some instance such as when you go over the hump, when an aircraft passed through a parabolic path, orbiting through the earth by Astronauts etc.
Thanks for your time
Note that all images are created by me
References
- https://github.com/leeyt/Physics/blob/master/8.01%20Classical%20Mechanics/07.%20Weight%2C%20Perceived%20Gravity%2C%20and%20Weightlessness.md
- https://www.wyzant.com/resources/lessons/science/physics/weightlessness
- https://www.britannica.com/science/weightlessness
- http://hyperphysics.phy-astr.gsu.edu/hbase/Mechanics/hump.html
- https://en.wikipedia.org/wiki/Weightlessness
