Circle/Sphere Touching: Perfection & Friction

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In summary: Atom%E2%80%93molecule_interaction2. If two atoms are touching, their wavefunctions will overlap. This means that the amplitude of each atom's wavefunction at the point where they overlap will be ridiculously small. However, the two atoms will still be influencing each other. In practice, if two atoms are more than a few nanometers apart, their influence on each other typically becomes so small that it is overshadowed by the influence of closer atoms. Therefore, although two atoms a mile apart may technically be touching (if we define touching as the overlap of atomic wavefunctions), this touching is typically so insignificant that it can be ignored
  • #1
Shropcakes
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Theoretically, if you had a perfect circle, and a perfectly flat surface, wouldn't only one atom touch at a time (assuming friction can't take away the perfect circle/flat surface)? Personally this doesn't sound right, but I can't think of why it wouldn't.
 
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  • #2
Shropcakes said:
if you had a perfect circle, and a perfectly flat surface, wouldn't only one atom
If they are made from atoms, how can they be perfectly flat or circular?
 
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  • #3
What do you mean by "touch"? That term does not have a clear meaning at the atomic scale.
 
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  • #4
mrspeedybob said:
What do you mean by "touch"? That term does not have a clear meaning at the atomic scale.
As close as possible. I'm not very knowledgeable of physics, so feel free to explain.
 
  • #5
A.T. said:
If they are made from atoms, how can they be perfectly flat or circular?
When I say perfectly round/flat, I mean as round or flat as atoms can get. I understand that because of the electron cloud, the round or flat part can never be the same.
 
  • #6
Shropcakes said:
When I say perfectly round/flat, I mean as round or flat as atoms can get. I understand that because of the electron cloud, the round or flat part can never be the same.

Then you've answered your own question. "As round or flat as atoms can get" is not the same thing as "perfectly exactly geometrically round or flat" so you already know that you cannot reason about this system as if it were perfectly flat and perfectly round.
 
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  • #7
Nugatory said:
Then you've answered your own question. "As round or flat as atoms can get" is not the same thing as "perfectly exactly geometrically round or flat" so you already know that you cannot reason about this system as if it were perfectly flat and perfectly round.
What is the difference?
 
  • #8
Shropcakes said:
What is the difference?

reread you own answer in post #5Dave
 
  • #9
So...as round as atoms can get means that on the atomic scale, the circle looks pretty flat, just as the round Earth looks pretty flat to our eyes.
 
  • #10
Shropcakes said:
I understand that because of the electron cloud, the round or flat part can never be the same.
If you understand that on the particle level you just have electron clouds, wobbling atoms and varying force fields, then you should see how pointless it is to ask questions based on idealized geometric shapes.
 
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  • #11
+1

http://sciencequestionswithsurprisinganswers.org/2013/04/16/do-atoms-ever-actually-touch-each-other/

1. If "touching" is taken to mean that two atoms influence each other, then atoms are always touching. Two atoms that are held a mile apart still have their wavefunctions overlapping. The amplitude of one atom's wavefunction at the point where it overlaps with the other atom's center will be ridiculously small if they are a mile apart, but it will not be zero. In principle, two atoms influence each other no matter where they are in the universe because they extend out in all directions. In practice, if two atoms are more than a few nanometers apart, their influence on each other typically becomes so small that it is overshadowed by the influence of closer atoms. Therefore, although two atoms a mile apart may technically be touching (if we define touching as the overlap of atomic wavefunctions), this touching is typically so insignificant that it can be ignored.
 
  • #12
CWatters said:
+1

http://sciencequestionswithsurprisinganswers.org/2013/04/16/do-atoms-ever-actually-touch-each-other/

There are other possibilities to define "contact", than the three mentioned there. But they might not be generally applicable. See also:

 
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1. What is meant by "perfection" in the context of circle/sphere touching?

In this context, perfection refers to a theoretical state in which two circles or spheres touch each other at a single point, with no overlap or gaps between them. This is also known as "tangent" or "point contact."

2. Can two circles or spheres touch each other perfectly in real life?

No, perfect tangency is a mathematical concept and cannot be achieved in the physical world due to imperfections in the objects and the surfaces they touch. However, with careful engineering and precise measurements, we can come close to achieving perfect tangency.

3. What is the significance of friction in circle/sphere touching?

Friction plays a crucial role in circle/sphere touching as it determines the amount of force required to keep the two objects in contact. In perfect tangency, there is no friction between the two objects, but in real-life situations, there is always some degree of friction that needs to be considered in engineering designs.

4. How is circle/sphere touching related to the concept of contact mechanics?

Circle/sphere touching is one of the fundamental concepts in contact mechanics, which studies the behavior of two objects in contact with each other. It involves understanding how forces are transmitted between the two objects and how they deform under the applied load.

5. What are some real-life applications of circle/sphere touching?

Circle/sphere touching has numerous applications in various fields, including engineering, physics, and mathematics. Some examples include ball bearings, car tires, and the contact between the wheels and the rails in a train. It is also essential in fields such as robotics, where precise contact between components is crucial for optimal performance.

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