Why Does a Book on a Table Stay at Rest Despite Action and Reaction Forces?

  • Context: High School 
  • Thread starter Thread starter moatasim23
  • Start date Start date
  • Tags Tags
    Law Third law
Click For Summary

Discussion Overview

The discussion revolves around the question of why a book resting on a table remains at rest despite the presence of action and reaction forces. Participants explore concepts of equilibrium, force pairs, and the distinction between action/reaction forces and forces acting on the book.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that action and reaction forces do not balance each other, leading to confusion about the book's state of rest.
  • Others clarify that the book is in equilibrium because the forces acting on it add up to zero, although these forces are not action/reaction pairs.
  • One participant identifies the gravitational force and the normal reaction force from the table as the two forces acting on the book.
  • Another participant emphasizes that while the gravitational force and normal force are equal and opposite, they are not third law pairs.
  • There is a discussion about identifying all forces acting on the book and their corresponding third law pairs, indicating a need for clarity on the concepts involved.

Areas of Agreement / Disagreement

Participants express differing views on the nature of action and reaction forces, with some asserting that they do not balance while others argue that they do. The discussion remains unresolved regarding the understanding of these concepts.

Contextual Notes

Participants have not fully agreed on the definitions and implications of action/reaction forces and equilibrium, leading to ongoing confusion and exploration of the topic.

moatasim23
Messages
77
Reaction score
0
Action and reaction do not balance each other.But then why a book lying on a table lies at rest?The reaction force and the gravitational force cannot balance each other.Then how is it?
 
Science news on Phys.org
moatasim23 said:
Action and reaction do not balance each other.But then why a book lying on a table lies at rest?The reaction force and the gravitational force cannot balance each other.Then how is it?
Action and reaction forces act on different bodies, so they don't 'balance'. The book is in equilibrium because the forces acting on the book add up to zero (they 'balance'). But those forces are not action/reaction pairs.

The first thing you need to do is identify all the forces acting on the book and their third law pairs.
 
Doc Al said:
Action and reaction forces act on different bodies, so they don't 'balance'. The book is in equilibrium because the forces acting on the book add up to zero (they 'balance'). But those forces are not action/reaction pairs.

The first thing you need to do is identify all the forces acting on the book and their third law pairs.

Can u help me to identify them?I can only think of two forces.
THANKS.
 
moatasim23 said:
Can u help me to identify them?I can only think of two forces.
OK, what are those two forces? And what bodies exert those forces? (That will help you identify the 3rd law pairs.)
 
hi moatasim23! :smile:

sorry, but i don't understand any of your post :confused:
moatasim23 said:
Action and reaction do not balance each other.

action and reaction are always equal and opposite
But then why a book lying on a table lies at rest?The reaction force and the gravitational force cannot balance each other.

they do balance each other

what makes you think that they don't? :confused:
 
Doc Al said:
OK, what are those two forces? And what bodies exert those forces? (That will help you identify the 3rd law pairs.)

Gravitational force and the upward normal reaction force of the table.
 
moatasim23 said:
Gravitational force and the upward normal reaction force of the table.
Good. Those two forces happen to be equal and opposite, thus the book is in equilibrium. But those two forces are not 3rd law pairs (action/reaction pairs).

The gravitational force on the book is exerted by the earth. The 3rd law pair to that force is an equal and opposite gravitational force exerted on the earth by the book. (They attract each other.)

The upward force of the table on the book is exerted by the table. The 3rd law pair to that force is an equal and opposite force exerted on the table by the book. (They push against each other.)
 
Thanks DOC AL.This question was confusing me for a lot time.Thanks a lot.
 

Similar threads

Undergrad Newton's Third Law: Action & Reaction Along the Line Connecting Two Objects
  • · Replies 5 ·
Replies
5
Views
2K
High School Are frictional forces action forces or reaction forces?
  • · Replies 14 ·
Replies
14
Views
2K
Undergrad Newton's third law in relation to field forces
  • · Replies 2 ·
Replies
2
Views
2K
High School Why Does a Ball Bounce Back from a Wall But Not from Sand?
  • · Replies 3 ·
Replies
3
Views
3K
Newton's Third Law for book on a table
  • · Replies 8 ·
Replies
8
Views
4K
Graduate Is Newton's Third Law a Manifestation of Fundamental Laws?
  • · Replies 4 ·
Replies
4
Views
5K
Graduate Elastic collisions and Newton's third law
  • · Replies 2 ·
Replies
2
Views
3K
Undergrad Confusion regarding Newton's Third Law of Motion
  • · Replies 10 ·
Replies
10
Views
12K
Undergrad Do action force and reaction force lie on same line?
  • · Replies 4 ·
Replies
4
Views
1K
Undergrad Conceptual problem on Newton's Third Law
  • · Replies 9 ·
Replies
9
Views
3K