What is the normal force?

The normal force is defined as the support force that is exerted upon an object that is in contact with a stable surface. It acts perpendicular (normal) to the surface with which the object is in contact. For instance, when a book rests on a table, the table exerts an upward normal force equal to the weight of the book, which acts downward due to gravity. This force is crucial in keeping the object stationary and balanced on the surface.

In scenarios where there are additional forces acting on the object, such as when the object is on an incline or when external forces are applied, the normal force may vary. Understanding the concept of the normal force is essential in solving problems related to static and dynamic friction, as well as forces in equilibrium.