What happens when two masses touch?

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In summary, classical electrostatics can't account for why two masses wouldn't just 'touch' and fuse.
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What happens when two masses touch? I mean, really touch. When I touch something, I know that the atoms in my hand are separated by some distance from the object I am touching, due to mutual repulsion by the electromagnetic force.

So, if two charge-less masses were to collide with each other, what force governs that interaction?
 
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  • #3
It's a question that simply cannot be answered by classical physics.

It was a big problem in the 19th Century that contemporary theory suggested that the most energetically favourable configuration of charged particle would be 'all on top of each other'.

It was only when Heisenberg came along that the 'exclusion principle' was formulated.

The idea is that these new laws predicted that two particles (like the neutral ones you mention) can never end up in the same place. As they get too close, the quantum mechanical 'degenerecy pressure' prevents them from ever 'overlapping'.

Not a great explanation, apologies.

Van der Waals forces are just one particular manifestation of classical electrostatics.

Incidentally, this degenerecy pressure is also the reason we never 'touch' anything ourselves. Classical electrostatics cannot account for that. Why would the atoms in our hand repel the atoms in the brick (or whatever)? Clasically, they would attract (due to polarisation within the atom), and then overlap, with the protons all hugging up to the electrons in a big particle soup.

Amazing to think that no-one before the beginning of the 20th century could even begin to explain why we don't fall through the floor.
 
  • #4
opsb said:
It was only when Heisenberg came along that the 'exclusion principle' was formulated.

Do you mean pauli
 
  • #5
Thanks, sorry. History a little shaky.
 
  • #6
The electromagnetic force still plays it's part with adjacent neutral masses "touching"...like your hand and a baseball...because the neutral masses consist of electron clouds surrounding nuclei...and the electron clouds come into first "contact"...

If they REALLY "touch" they might fission or fuse as in bombs...or form a new compound like hydrogen and oxygen to form water...
 

1. What happens when two masses touch?

When two masses touch, they experience a force called the normal force. This force is perpendicular to the surface of contact and is equal in magnitude to the force pushing the two masses together. The normal force prevents the two masses from passing through each other and determines the amount of compression or deformation that will occur.

2. Does the mass of the objects affect what happens when they touch?

Yes, the mass of the objects affects what happens when they touch. The normal force is directly proportional to the mass of the objects. This means that the heavier the masses are, the greater the normal force will be.

3. What other forces are involved when two masses touch?

In addition to the normal force, there may also be other forces involved when two masses touch, such as the force of gravity, friction, and electromagnetic forces. These forces can affect the motion and behavior of the masses when they touch.

4. Can two masses touch without any forces acting on them?

No, two masses cannot touch without any forces acting on them. According to Newton's first law of motion, an object will remain at rest or continue moving at a constant velocity unless acted upon by an external force. Therefore, the two masses must experience some type of force to come into contact with each other.

5. What determines the behavior of the masses when they touch?

The behavior of the masses when they touch is determined by a combination of factors, including the forces acting on them, the properties of the materials they are made of, and the relative velocities and positions of the masses. These factors can result in a range of outcomes, from elastic collisions where the masses bounce off of each other, to inelastic collisions where the masses stick together after contact.

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