How does table exert force on me?

In summary, when you slam your hand on a table, the force you exert on the table is also exerted back on your hand due to the rigidity of the table's atoms and molecules and their resistance to compression. This force does not require any energy to work and is a result of the charged particles in the atoms constantly exerting forces on objects around them. This idea can be difficult to understand, but it is explained by Newton's Third Law and the strength of molecular forces in solid objects. Changing your perspective of motion can also help in understanding this concept.
  • #1
Erika E.
5
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I now this is a very fundamental idea, that when I slam my hand on a table, the force that I exert on the table is also exerted back to my hand, if this were not true then the table would move in the direction that I hit it or I would make a dent in it. This idea is hard for me to grasp, because I don't understand how an inanimate object can get energy to exert force on my hand? I think it has something to do with the atoms, and the energy they hold, maybe? Thanks.
 
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  • #2
Erika E. said:
I now this is a very fundamental idea, that when I slam my hand on a table, the force that I exert on the table is also exerted back to my hand, if this were not true then the table would move in the direction that I hit it or I would make a dent in it. This idea is hard for me to grasp, because I don't understand how an inanimate object can get energy to exert force on my hand? I think it has something to do with the atoms, and the energy they hold, maybe? Thanks.

When you slam your fist down on a table, the table compresses slightly, just like a spring. The force of the table on your hand is the resistance to compression.
 
  • #3
When your hand contacts the table the atoms and molecules in the table repel those in your hand. This force requires no energy to work, as atoms are made of charged particles that always exert forces on things around them and never stop. In fact, energy is a result of these forces acting on objects and accelerating them. For example, a book sitting on a table is repelled by the table, otherwise it would pass through it, yet no energy is expended and no work is performed on either the book or the table.
 
  • #4
The resisting force provided by the table is NOT the force of atoms and molecules repelling those in your hand and it has nothing to do with the charge of particles. It is the strength of the structure of the atoms and molecules, the rigidity of the material, and it's resistance to compression. Consider what would happen if you slapped the surface of water vs. a pillow vs. a wooden table.
 
  • #5
AndrewBerkeley said:
The resisting force provided by the table is NOT the force of atoms and molecules repelling those in your hand and it has nothing to do with the charge of particles.

To clarify, the rigidity of the table is exactly what you said it was and is the reason the table doesn't collapse. The force repelling your hand works just like I said it does.

AndrewBerkeley said:
It is the strength of the structure of the atoms and molecules, the rigidity of the material, and it's resistance to compression. Consider what would happen if you slapped the surface of water vs. a pillow vs. a wooden table.

Absolutely.
 
  • #6
@Erika E., You are right about the energy coming from molecular forces. You have probably not realized the strength of molecular forces in a solid object. They are enormous compared with the forces that we are used to observing in daily life. Most people think that the force of gravity is strong. When something falls 30 feet, it is pulled by the entire Earth and accelerates to a fast speed in that 30 feet. If it hits concrete, it will stop dead in millimeters just from the molecular forces in that tiny impact area. Those local molecular forces are many orders of magnitude stronger than the gravitational attraction of the entire Earth. That is where the energy comes from.
 
  • #7
All you need to know is Newton's Third Law, that's all. You don't have to care about energy, mocule or quantum or even temperature of black hole.
 
  • #8
Erika E. said:
This idea is hard for me to grasp, because I don't understand how an inanimate object can get energy to exert force on my hand?
best way to grasp this is to change your perspective of motion .
an ant sitting on your hand as you hit table, will instead think that table (along with planet earth) is hitting your hand, not the other way round
 
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1. How does the table exert force on me?

The table exerts force on you through the interactions of the molecules in your body and the molecules in the table. These interactions create a force called normal force, which is the force that keeps you from falling through the table.

2. Why do I feel the table pushing against me?

You feel the table pushing against you because of the normal force. This force is directed perpendicular to the surface of the table and is equal in magnitude to the force you are exerting on the table. This creates the sensation of the table pushing against you.

3. Does the type of material the table is made of affect the force it exerts on me?

Yes, the type of material the table is made of does affect the force it exerts on you. Different materials have different molecular structures and strengths, which can affect the amount of normal force exerted on you. For example, a table made of wood may exert less force than a table made of metal.

4. How does the weight of the table affect the force it exerts on me?

The weight of the table does not directly affect the force it exerts on you. The force exerted on you is determined by the normal force, which is equal to the force you are exerting on the table. However, a heavier table may require more force to hold up, resulting in a greater normal force being exerted on you.

5. Can I change the force the table exerts on me?

Yes, you can change the force the table exerts on you by changing the force you are exerting on the table. For example, if you push down harder on the table, the normal force will increase. Additionally, you can change the materials or weight of the table to alter the force it exerts on you.

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