Doc Al said:What book are you using? Does the book give an explanation or just make a statement?
I would say that in the usual sense of the term you can have a zero normal force between surfaces in contact.
Yes, normal forces always exist when surfaces are in contact. Normal forces are perpendicular to the surface of contact and are present whenever two surfaces are touching each other.
A normal force is a contact force that acts perpendicular to the surface of contact between two objects. It is a reaction force that prevents objects from passing through each other.
No, normal forces can vary in magnitude and direction depending on the weight and orientation of the objects in contact. However, they are always perpendicular to the surface of contact.
Yes, normal forces can exist between non-solid objects such as liquids and gases. In these cases, the normal force is caused by the pressure exerted by the fluid on the object.
Yes, normal forces can be greater than the weight of an object when additional forces such as friction or external forces are present. This is known as an "overcoming" normal force and is necessary for an object to be in equilibrium.