A question regarding action and reaction

  • #1

Main Question or Discussion Point

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?
 

Answers and Replies

  • #2
jtbell
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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?
 
  • #3
What is your source for "science says" this?
I have given a caveat also....''Am I on the right track..''
 
  • #4
jtbell
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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?
 
  • #5
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....
 
  • #6
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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.
 
  • #7
jtbell
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1. Electrons of fist and bench come together...but their force of repulsion is not strong enough I think...
Why not?
 
  • #8
jbriggs444
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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.
 
  • #9
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
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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
russ_watters
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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
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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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