Is the Total Force Between a Book and the Earth 10 N?

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Homework Help Overview

The discussion revolves around the concept of gravitational force between a book and the Earth, specifically questioning the interpretation of forces acting on each other according to Newton's third law. Participants explore the implications of these forces in a physics context.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants examine the idea of total force between two objects and question whether the forces they exert on each other can be summed. There is a focus on understanding how gravitational forces operate and the relevance of forces acting on the book versus those acting on other objects.

Discussion Status

The discussion is active, with participants offering different perspectives on the nature of gravitational forces and the implications of Newton's laws. Some guidance is provided regarding the relevance of forces acting on the book specifically, while others challenge the notion of summing forces between separate bodies.

Contextual Notes

Participants are navigating assumptions about gravitational interactions and the definition of total force in this context. The discussion highlights the need for clarity on how forces are perceived in relation to different objects and their interactions.

defetey
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This is not really a homework question, just a question I came up with. If the Earth is pulling, for example, a book with a force of 5 N, that means, due to Newton's 3rd law, that the book is also pulling the Earth with a force of 5 N.

Does this mean the total force between them is actually 10 N (since they are each pulling each other with a force of 5 N)? That would imply you would need over 10 N to pick up the book, but I know you only need anything over 5 N. So what am I missing here?
 
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defetey said:
This is not really a homework question, just a question I came up with. If the Earth is pulling, for example, a book with a force of 5 N, that means, due to Newton's 3rd law, that the book is also pulling the Earth with a force of 5 N.

Does this mean the total force between them is actually 10 N (since they are each pulling each other with a force of 5 N)? That would imply you would need over 10 N to pick up the book, but I know you only need anything over 5 N. So what am I missing here?

I believe it is because the only forces being exerted on the book are by you and the earth. Whatever force the book exerts on anything else is irrelevant; the only relevant forces are the ones acting on the book.
 
But if something was between them, would it experience 10 N of force (5 from the book and 5 from the Earth)?
 
no it wouldn't ... gravitational force is field force acting on any mass by any mass..
So the thing in between would experience a force based on it mass according to Newtons law of gravitation by both the Earth and the book but their magnitudes would be different(not 5N).

And there's no 10N force ... since 5 acts on the book and 5 on the Earth which are both separate bodies.
 

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