A question regarding action and reaction

AI Thread Summary
The discussion centers on the physics of action and reaction, specifically when a fist strikes a bench. Participants explore the role of atomic nuclei and electron interactions, debating whether repulsion between the nuclei or electrostatic forces are responsible for the reaction felt. One contributor emphasizes that the equal and opposite reaction is fundamentally about symmetry rather than the strength of forces involved. They clarify that while nuclear forces are strong at short ranges, electrostatic forces dominate at larger distances, impacting everyday interactions. Ultimately, the conversation highlights the complexity of atomic interactions in understanding physical reactions.
Deepak K Kapur
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I hit a bench with my fist, I experience equal and opposite reaction...

Science says, it is because the nuclei of the atoms of my fist come close to the nuclei of atoms of the bench and experience repulsion.

Am I on the right track?...Are there other explanations?
 
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Deepak K Kapur said:
Science says, it is because the nuclei of the atoms of my fist come close to the nuclei of atoms of the bench and experience repulsion.

What is your source for "science says" this?
 
jtbell said:
What is your source for "science says" this?
I have given a caveat also...''Am I on the right track..''
 
If it's your thought, you should not say "science says." :smile:

As the nuclei of the atoms of your fist and the bench come closer together, what parts of those atoms come even closer together?
 
jtbell said:
If it's your thought, you should not say "science says." :smile:

As the nuclei of the atoms of your fist and the bench come closer together, what parts of those atoms come even closer together?
Ok, I thought this but well within the parameters of established science...:oops:

I think when my fist touches the bench...the following happens

1. Electrons of fist and bench come together...but their force of repulsion is not strong enough I think...

2. Protons in the nuclei of fist and bench come together...this repulsion I think is strong enough to provide the reaction...well, may be...
 
Deepak K Kapur said:
1. Electrons of fist and bench come together...but their force of repulsion is not strong enough I think...
Have you ever tried touching the north or south poles of magnets together? Electrons and magnetism are inseparable.
 
Deepak K Kapur said:
1. Electrons of fist and bench come together...but their force of repulsion is not strong enough I think...
Why not?
 
Deepak K Kapur said:
I have given a caveat also...''Am I on the right track..''
No. You are on the wrong track. The answer to the question of why action and reaction are equal has nothing to do with the nature of the force or how strong it is and everything to do with symmetry. If you press on the table, the table is pressing back on you. Whether that force is sufficient to prevent your hand from going through the table does not enter in.
 
jtbell said:
Why not?
Because electrostatic force is much weaker than nuclear force. Even in day to day chemical reactions, electrons move between atoms...so, I think they are not 'put' enough to resist strong actions.

For eample, if I drop a heavy iron ball on the bench from a height...the bench would break...in other words, the electrons have 'given way' and chemical bonds have broken..
 
  • #10
Deepak K Kapur said:
electrostatic force is much weaker than nuclear force.
At what ranges are you judging this from? Nuclear forces are limited in range, but electrostatic forces are infinite.
 
  • #11
Deepak K Kapur said:
Because electrostatic force is much weaker than nuclear force. Even in day to day chemical reactions, electrons move between atoms...so, I think they are not 'put' enough to resist strong actions.

For eample, if I drop a heavy iron ball on the bench from a height...the bench would break...in other words, the electrons have 'given way' and chemical bonds have broken..
I think you just accidentally argued (correctly) that your previous reasoning was wrong: It is indeed the electron interactions at play EVERYWHERE in the example of the bench, whether it breaks or not.
 
  • #12
Deepak K Kapur said:
Because electrostatic force is much weaker than nuclear force.
There are two problems with this. First, the strong nuclear force is attractive. It is the force that keeps the nucleus together even though all of the positively charged protons are pushing away from each other through the electrostatic interaction. So if this interaction were governed by the strong nuclear force it would be attractive, not repulsive. Second, the electrostatic force is only weaker than the strong nuclear force at very short distances, specifically at distances about the size of a nucleus. Beyond those distances the electrostatic force is actually stronger.
 
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