Question

A book is lying on a table . Name the forces applied on the book and how is it balanced according to newton's third law of motin?

Answer 1

There 2 pairs of forces acting on the book or by the book i.e. in total 4 forces .
1st pair : The Normal Force by the surface of the table on the book.
               The Normal Force by the book on the surface.
(cancelling each other out)
2nd Pair: The gravitational force by the earth on the book
               The gravitational force by the book on the earth(Though not strong enough :P)
(cancelling each other out)
These Pairs are cancelling each other out and are action-reaction pairs (
Now since the book is at rest i.e. there is no net force acting on it.
∑Fₓ = 0 
OR  N  - W =0 ( Since these are the two forces acting on it , N=Normal,W= Weight)
 N = W = mg 
Therfore they are equal in magnitude but are not action-reaction pairs
and these are the two forces acting on it.