A question regarding action and reaction

In summary, the equal and opposite reaction experienced when hitting a bench with a fist is due to the repulsion between the nuclei of the atoms in the fist and the bench. This is supported by the fact that electrons, which are responsible for the electrostatic force, are not strong enough to resist strong actions such as dropping a heavy iron ball on the bench from a height. However, this reasoning is flawed as the electrostatic force is infinite in range and becomes stronger at longer distances. Additionally, the strong nuclear force, which is responsible for keeping the nucleus together, is actually attractive rather than repulsive. Therefore, the equal and opposite reaction is a result of symmetry rather than the strength of the force.
  • #1
Deepak K Kapur
164
5
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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  • #2
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?
 
  • #3
jtbell said:
What is your source for "science says" this?
I have given a caveat also...''Am I on the right track..''
 
  • #4
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
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...
 
  • #6
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.
 
  • #7
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?
 
  • #8
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.
 
  • #9
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.
 

Related to A question regarding action and reaction

What is Newton's Third Law of Motion?

Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal force in the opposite direction.

How does Newton's Third Law apply to everyday life?

This law can be observed in many everyday situations, such as when we walk. As our foot pushes against the ground, the ground pushes back with an equal force, allowing us to move forward. It also explains the recoil of a gun when fired, as the force of the bullet leaving the gun is equal to the force pushing the gun backwards.

Can Newton's Third Law be violated?

No, this law is a fundamental principle of physics and has been repeatedly proven through experiments and observations. It is a fundamental law of nature and cannot be violated.

Is Newton's Third Law the same as the Law of Conservation of Momentum?

No, although they are related, they are not the same. Newton's Third Law deals specifically with action and reaction forces, while the Law of Conservation of Momentum states that the total momentum of a system remains constant unless acted upon by an external force.

How does Newton's Third Law relate to the concept of force pairs?

Newton's Third Law can be understood through the concept of force pairs, which states that every action force has an equal and opposite reaction force. In other words, the force exerted by one object on another is always matched by a force exerted by the second object on the first object in the opposite direction.

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