A) consider the following statement made by a student about a book at rest on a

Question

A) consider the following statement made by a student about a book at rest on a level table:

"The two forces exerted on the book are the normal force directed in the upward direction and the weight of the book directed downward. These are equal and opposite to each other. By newtons third law these two forces are a "force pair". So the normal force is always equal to the weight of the book."

-Do you agree with the student? explain why you agree or disagree.

B) COnsider a book on top of a level table while the book is being pressed straight down by a hand.

i) how do the forces exerted on the book in this case compare to the forces on the book when the hand was not present pushing down on the book? List any of the forces that are the same (magnitude/direction) and list the ones that change.

ii) is the magnitude of the weight equal to the magnitude of the normal force in this case? How can you tell?

Explanation / Answer

A) This statement is not true always , because if book is placed on inclined table then normal force will be equal to a component of weight .


B)
1) Normal force will change ( now it will be equal to weight of book + force exerted ) , direction will remain same but magnitude will change.

and gravity force i.e. weight frce will remain same .

2) No, magnitude of the weight is not equal to the magnitude of the normal force in this case
beacuse if we balance forces then normal will be equal to the sum of weight of book and the force exerted.

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