a book of 10N is placed on the table.the force exerted by the surface of the table on the book will be: pls. explain with formula.give me other formulae about friction.

according to newton's third law.

Every action has an equal and opposite reaction.

The book exerts a reaction force of 10N on the table.

the table exerts an opposite reaction force of -10N on the table.

minus just shows that the force exerted by surface is in opposite direction to the actual force applied.

F_AB= -F_BA

Please approve

given that the weight of the book is 10N

as the book is placed on the table the weight(mg)is balanced by the normal reaction force applied on the book by the table

therefore mg=N=10N

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here you have not mentioned about friction 

there is no friction in the above case as the book is at stationary with respect to the table

the formula for frictional force is the product of the normal force on the body(N) and the coefficient of friction which will be given in the problen itself