Science question! newtons, force...?

Question

Plllleeeeaaasse i need help!

Consider a book that weighs 15 newtons and is at rest on a flat table. How many newtons of support force does the table provide? What is the net force on the book?

Answer 1

Newton's second law tells us that an object with no net force on it does not accelerate. If it is at rest, it will remain at rest.

Since your book is not accelerating, the net force on it must be zero. There are 15 newtons of gravitational force (downward), so there must be 15 newtons of force (upward) generated by the table.

Additionally:
Newton's third law also tells us that forces come in pairs, equal in magnitude but opposite in direction. The table exerts 15 N upward on the book, so the book exerts 15 N downward on the table.

Answer 2

Firstly, a net force results when forces acting on a body are unbalanced.

In other words, a net force results if individual forces in the opposite direction are added and they do not cancel each out other completely.

Further, whenever there is a net force; acceleration occurs.
(a rough restatement of Newton's 2nd law)

So, if a book is at rest (or is not accelerating) it means that the forces acting on the book must be balanced.

It follows then, that the support force from the table must be equal in size (but in the opposite direction to) the weight force of the book.

Hence, 15 newtons of force is provided by the table.

Here's a link that explains the above using diagrams:
http://www.glenbrook.k12.il.us/gbssci/phys/CLass/newtlaws/u2l1d.html

Answer 3

I am not very sure but I think net support force should be 15 newtons opposite direction and Net Force on the book should be 0

Answer 4

The table is a mass structure in the form of a beam.
The Force on the beam depend on the acceleration of the mass pushing down on the table whci acts as a beam.
The beam will hold up the force on the mass due to gravity by its legs.The 4 legs will divide the reactive force pushing up against the weight of the mass.
As per newton third law to every force there is a reactive force. Note acceleration =Weight per Unit mass
So the sum of the reactive forces will be equal by opposite to the weight of the mass on the table. Even though the book is accelerating on top of the table its going no where.
Now instead of a book you are on top of the table Holding a 35 kilogram kid on your shoulders what would be the net force on top of you.