Join two broke pieces of the same material

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Discussion Overview

The discussion revolves around the question of why two broken pieces of the same material, such as wood, do not rejoin when pressed together, despite atomic attraction. Participants explore the differences in behavior between materials like wood and metal, the effects of surface modification, and the energy requirements for atomic bonding.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why atoms do not rejoin when two pieces of broken wood are pressed together, suggesting that atomic forces should facilitate this process.
  • Another participant explains that while metals can bond under specific conditions (clean surfaces and vacuum), wood's surface modification during breakage creates irregularities that prevent clean rejoining.
  • A participant challenges the need for energy in the bonding process, questioning the nature of atomic attraction.
  • Further clarification is provided that not all atoms attract each other uniformly, and energy may be required to initiate bonding, even if energy can be released afterward.
  • An analogy involving wood burning is used to illustrate that energy must be supplied to initiate a reaction, rather than relying solely on atomic attraction.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of energy for atomic bonding and the nature of atomic attraction, indicating that multiple competing perspectives remain without consensus.

Contextual Notes

The discussion highlights the complexity of atomic interactions and the specific conditions required for bonding, which may depend on material properties and surface conditions. Unresolved assumptions about atomic behavior and energy dynamics are present.

scientifico
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Hello, if I broke for example a piece of wood in two pieces I give the atoms enough force to separate in the break point with the others, so why putting the two pieces together and pressing them the atoms don't join again ?

Thank you!
 
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This is possible with metal, but it has to be extremely clean and in a vacuum.
If you break wood, you modify the surfaces, if you try to combine them again you get a lot of ripples which do not fit. And on a molecular level, you need energy to combine the parts as well, which would be released as heat afterwards.
 
why would I need energy if atoms attract each others?
 
scientifico said:
why would I need energy if atoms attract each others?
Deformation of the material during breakage would prevent you from joining them cleanly afterward.
 
scientifico said:
why would I need energy if atoms attract each others?
Atoms do not generally attract each other. Some do, some do not. In many cases, you have to add some energy to the system first, even if you can extract more energy afterwards.

Think of a wood fire: It burns, and it can release a lot of heat. But if you just place wood somewhere, it does not begin to burn. You have to add energy first.
 

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