Thesis Abstract and Dissertation Abstracts

Action of a book on a table:
When a book is kept on a table, its weight presses the table. Weight is the gravitational force. It acts relentlessly. This phenomenon of gravity raises the question, why the book is in equilibrium ? The answer had been that the table reacts with an equal and opposite force.

If so following three questions arise:
1. If for every action there is equal and opposite reaction, Can there be any action at all ?
2. Every action needs energy. In the same way, reaction, too, needs energy. As for the action, it is evident that the energy needed comes from within the body, or is supplied from outside, or by interaction of the body with other bodies such as gravity, magnetism etc and combination of different factors.
As for reaction, from where does the force of reaction gets the energy ? It is not evident that there is energy available.
3. Why does the table deforms irreversibly or break when a ton of books are laid on it? Why there is no equal and opposite reaction to stop the table from breaking?

Answer to the question No.1
The first question opens many arguments. Or the answer is just evident. If for every action there were equal and opposite reaction, then there can be neither action nor reaction. Because, every action is cancelled by the equal and opposite reaction from the very beginning.

Answer to the question No.2:
In the action of the book on the table, the force is the weight. If a force exists, then energy exists. In the case of the book on the table, the energy is the gravitational potential energy.
If reaction did exist, there must be supply of energy to have the force of reaction. It is not evident that such a force exists.
How is the Equilibrium attained ?
Before the book is laid on the table, the molecules of the table are in equilibrium. That means the internal forces of the molecules are balanced. When the book is laid on the table, the weight of the book presses the molecules of the table. It results in sqeezing the molecules in the upper part and legs of the table, and stretching the molecules in the lower part of the plank of the table. This means: equilibrium is attained in new positions, size and form of the molecules.
To change positions work is done. The work done is the force in action multiplied by the distance shifted. The work done is also said to be the stored energy.
In equation-form: work done = force x distance moved.
Stored energy = weight x distances (new positions, sizes and forms of the molecules)
The energy which comes into the table is stored as potential energy in the molecules of the table. It is stored in elasticity. In the same time a little amount is lost to the surroundings as heat.
Since the energy in the force of action gets stored as potential energy in the molecules of the table, the action does not need a force of reaction to bring the book to equilibrium.
The equilibrium with the book and the table is an active equilibrium. Because the weight of the book is ever present. The squeezed and stretched molecules of the table will remain squeezed and stretched as long as the book is on the table ( a spring effect).
When the book is removed from the table, the pressured molecules come back to their original positions. The energy for the return movement comes from the stored energy in the molecules. The stored energy is the gravitational energy taken from the book. And a little amount that has been lost as heat is taken back from the surrounding.
But, the state of equilibrium has a limit. It is called the limit of elasticity. It varies from object to object and material used. As soon as the limit is crossed the table deforms or breaks irreversibly.

Answer to the question No.3:
When large amount of books are laid on the table, the plank or the legs of the table deform and/or break irreversibly. The force exerted by the books are so much that the force of bondage of the molecules are not enough to hold the molecules together.
When the breaking or deformation occurs in the stretched side of the plank, the molecules are pulled apart from one another so much that the intermolecular force of bondage is not strong enough to hold the molecules together. The bondage snaps.
In the squeezed side, the force of the books brings the molecules so much together that the molecules begin to slide past one another. The instant when they begin to slide, the structure breaks. The week point varies from material to material. For instance: fibrous materials like wood fail in the stretched side; hard materials like stone, concrete can fail on both sides; some of the plastics deform and never break.

Summary:
In an action of a book on a table, the energy brought in by the weight is stored as potential energy in the molecules of the table. The storage remains as long as the weight is acting and the force is within the limit of elasticity of the table. If the weight exceeds the elasticity, the table deforms and/or breaks irreversibly.
In both cases, there is no force of reaction. In the first case the energy involved gets stored as potential energy, and in the second, it goes to deform and/or break the table.
When the weight is removed, the molecules get back to the original positions, sizes and forms. The energy needed to get back is the stored energy.
Copyright: Hamsen B Paramahamsa snb1898@gmail.com or eecoltd2@gmail.com

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Submission Details: Paper Abstract submitted by Balasupramaniam Paramahamsa from Germany on 17-Sep-2013 19:51.
Abstract has been viewed 2423 times (since 7 Mar 2010).

Balasupramaniam Paramahamsa Contact Details: Email: eecoltd2@gmail.com