a book weighs 6 n. when held at rest above your head the net force on the book is?
You must be pushing up with 6N.
To find the net force on the book when held at rest above your head, we need to consider the forces acting on the book. In this case, there are two forces acting on the book: the force of gravity pulling the book downwards and the force exerted by your hand supporting the book.
Since the book is held at rest, it means that the net force acting on it is zero. This is because the force exerted by your hand cancels out the force of gravity pulling the book downwards. The force exerted by your hand is equal in magnitude and opposite in direction to the force of gravity.
So, when the book is held at rest above your head, the net force on the book is zero.