Forces of gravitation of moon and earth + Newtons 3rd law

AI Thread Summary
The discussion centers on the gravitational forces between the Earth and the moon, specifically whether there are two pairs of partner forces as described by Newton's third law. It is clarified that the gravitational force exerted by the Earth on the moon is equal in magnitude and opposite in direction to the force exerted by the moon on the Earth. Participants note that while the Earth's gravitational pull is stronger due to its greater mass, the forces themselves remain equal according to Newton's law of gravitation. The confusion arises from the differing gravitational strengths experienced on each body, but the fundamental principle of equal and opposite forces holds true. Overall, the interaction exemplifies Newton's third law, emphasizing that forces between two masses are equal regardless of their individual gravitational strengths.
Abhishek Jain
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In relation to two objects with a gravitational field on them (i.e. a planet and its moon), would there be two pairs of partner forces (the force of gravity exerted from each object and the resulting partner force from each force of gravity)? For example with the Earth and moon:

1. Force of gravity exerted on the moon by the Earth = - Force exerted on Earth by moon
2. Force of gravity exerted on the Earth by the moon = - Force exerted on moon by earth

Or is the force of gravity exerted by the moon on Earth = - force of gravity exerted by the Earth on moon? My intuition would say my first answer is correct?
 
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Abhishek Jain said:
is the force of gravity exerted by the moon on Earth = - force of gravity exerted by the Earth on moon
This one.

The gravitational interaction between the Earth and moon results in one pair of forces.
 
They would have to be equal though? Isn't the force exerted by the moon's gravitation on the Earth going to be less than the force exerted by the Earth's gravitation on the moon (since gravity is less on the moon)?
 
Abhishek Jain said:
They would have to be equal though?
Equal magnitude, opposite direction. Yes.
Abhishek Jain said:
Isn't the force exerted by the moon's gravitation on the Earth going to be less than the force exerted by the Earth's gravitation on the moon (since gravity is less on the moon)?
Work it out. What does Newton's law of gravitation say?
 
Thanks! I didn't know that G is the same between any two objects. That was what was confusing me!
 
Abhishek Jain said:
They would have to be equal though? Isn't the force exerted by the moon's gravitation on the Earth going to be less than the force exerted by the Earth's gravitation on the moon (since gravity is less on the moon)?

But the Earth is more massive than the moon and the force is based on the product of the masses.
 

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