the book cannot change its direction of motion
The Net external forces is the result force of two objects acting upon it. So if like two forces act on a book. One force exerts downward on the book and the other force pushes the table back on the book with the same amount of push and pull. Since both forces are pushing on each other with the same amount of energy the resultant force or net external force will be in equilibrium or zero.
Electrical forces act between separated charges.
Foreces that are applied to or act at the same point.
If the sum of all forces acting upon an object is not zero, then the object will accelerate. (Newton's first law)
Contact forces must be touching whatever they are acting on the others have a field of influence around them; ie they don't have to touch to act on something
The main forces acting on a book sitting on a table are the force of gravity pulling it downwards and the normal force exerted by the table pushing upwards to support the weight of the book. These two forces are equal in magnitude and opposite in direction, resulting in a state of equilibrium where the book remains stationary.
Balanced forces act on an object when the forces pushing or pulling it cancel each other out, resulting in no motion. For example, when a book is resting on a table, the downward force of gravity is balanced by the upward force exerted by the table, keeping the book stationary.
Equal and opposite forces that do not produce an acceleration are called balanced forces. When these forces act on an object, the net force is zero, causing the object to remain at rest or to move at a constant velocity without changing its speed or direction.
The two forces that act on a dropped book as it falls to the floor are gravity, which pulls the book downward, and air resistance, which pushes against the book as it falls.
The force of gravity causes a book to fall, but someone has to push it to the edge of the desk, or off the desk so that the force of gravity is greater than the normal force acting on the book.
Gravity, Air resistence, friction and the push from the floor/table
The support force from the table balances the weight of the book, preventing it from rising. As long as the support force equals the weight of the book, the book will remain at rest on the table due to Newton's First Law of motion.
The Net external forces is the result force of two objects acting upon it. So if like two forces act on a book. One force exerts downward on the book and the other force pushes the table back on the book with the same amount of push and pull. Since both forces are pushing on each other with the same amount of energy the resultant force or net external force will be in equilibrium or zero.
"Sit" is used to describe the act of being seated or the act of sitting down, such as "Please sit down." "Set" generally refers to placing something in a particular position, like "Please set the book on the table."
setting is the act of putting something somewhere else ie- setting the the table sitting is being a position where you knees and waist are bent at approximately a 90 degree angle
This book is Philosophiae Naturalis Principia Mathematica.
The answer to this is in your text book. Stop short-cutting and read it.