Normal force

The normal force is the supportive force exerted by a surface that counteracts an object's weight, preventing it from falling through. For example, when a book rests on a table, the table pushes upward with a normal force equal to the book’s weight, allowing it to stay still. This force acts perpendicular (at right angles) to the surface. The magnitude of the normal force can vary depending on the contact conditions; it equals the weight when the object is at rest on a flat surface without other forces acting vertically. It’s essential in understanding how objects stay in place or move across surfaces.