Can gravitational force be reactive?

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Discussion Overview

The discussion revolves around the nature of gravitational force in relation to Newton's third law of motion, particularly whether gravitational forces can be considered reaction forces. Participants explore examples and analogies involving different types of forces, such as electromagnetic forces and inertia, to question and clarify the principles of action and reaction in various contexts.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants argue that if the Earth attracts the Moon with gravitational force, then the Moon must also attract the Earth with an equal and opposite force, questioning whether this can be classified as a reaction force.
  • Others suggest that the nature of the forces involved in action and reaction pairs must be the same, raising questions about the classification of gravitational and electromagnetic forces.
  • A participant proposes that when pushing a car, the action force is electromagnetic, and the reaction force felt is due to inertia, which they argue is of a different nature than the action force.
  • Another participant challenges the idea of a 'force of inertia' and asserts that both forces in the car-pushing example are electromagnetic in nature.
  • Some participants seek clarification on whether action and reaction forces must be of the same nature according to Newton's laws, with mixed responses regarding this requirement.
  • There is a discussion about the gravitational force acting on an object falling to Earth and the corresponding reaction force, which is the object's gravitational force on the Earth.

Areas of Agreement / Disagreement

Participants express differing views on whether action and reaction forces must be of the same nature, and the discussion remains unresolved regarding the classification of gravitational forces as reaction forces.

Contextual Notes

Some arguments depend on interpretations of Newton's laws and the definitions of forces, which may not be universally agreed upon. The discussion includes speculative reasoning about forces in isolated systems and the nature of inertia.

xAxis
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If Earth attracts the Moon with gravitational force, then according to 3,rd Newton's law the Moon attracts the Earth with the same but opposite force. But what if someone argues that the Moon attracts the Earth anyway due to its own gravitation, can we really say that it's the reaction force?
Another example: You push the car. Here the action force is electromagnetic. The car pushes you back and it's the reaction force, electromagnetic. So it seems that action and reaction must be the forces of the same nature. But what if someone uses the same argument here, and explains the third Newton law like this:
When you push the car, the action force is electromagnetic. Because of the inertia of the car, it oposes the push and you feel the reaction force. Thus, here the reaction force is the force of inertia and is therefore of different nature than the action force.
So two questions:
1 Is this explanation of the 3.rd Newtons law better than the first one?
2 Can gravitational force really be force of reaction?
 
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Lookup some numbers (google calculator). Calculate the force of the moon's gravity attracting the earth. Then calculate the force of the Earth's gravity attracting the moon. Learn by exploration. It's not a matter of whether it is the reaction force. The reaction law just asserts that there will be such a force.
 
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xAxis said:
If Earth attracts the Moon with gravitational force, then according to 3,rd Newton's law the Moon attracts the Earth with the same but opposite force. But what if someone argues that the Moon attracts the Earth anyway due to its own gravitation, can we really say that it's the reaction force?
Another example: You push the car. Here the action force is electromagnetic. The car pushes you back and it's the reaction force, electromagnetic. So it seems that action and reaction must be the forces of the same nature. But what if someone uses the same argument here, and explains the third Newton law like this:
When you push the car, the action force is electromagnetic. Because of the inertia of the car, it oposes the push and you feel the reaction force. Thus, here the reaction force is the force of inertia and is therefore of different nature than the action force.
So two questions:
1 Is this explanation of the 3.rd Newtons law better than the first one?
2 Can gravitational force really be force of reaction?

In what sense electromangetic are u talkin in refrence to friction which is produced due to electromagtic intraion b/w two surface.
Now Newtons 3rd law is not a general term it always exists in pairs as you know. Gravitaion is again not a general term it also exsists in pair consider this in clasical physics a planet is there in an insolated space and think that there is no other planet or star think it is completely isolated. what could you think what will be its stabiltiy and gravitation
 
xAxis said:
When you push the car, the action force is electromagnetic. Because of the inertia of the car, it oposes the push and you feel the reaction force. Thus, here the reaction force is the force of inertia and is therefore of different nature than the action force.
I have not heard of a 'force of inertia' as such. In the example you have given, both force pairs are electromagnetic in nature.
 
I'd like to know if action and reaction must be forces of the same nature according to Newton.
When the object falls to Earth, we say it falls (accelerates) due to gravitational force. If you push an object it accelerates due to which force?
 
xAxis said:
I'd like to know if action and reaction must be forces of the same nature according to Newton.
Yes.
When the object falls to Earth, we say it falls (accelerates) due to gravitational force.
OK. And the 3rd law pair to the force of the Earth's gravitational force on the object is the object's gravitational force on the Earth.
If you push an object it accelerates due to which force?
You exert a contact force on the object, which is fundamentally electromagnetic; the object, per Newton, exerts an equal but opposite contact force on you, also electromagnetic.
 

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