Here's why:
* Definition: The normal force is the force exerted by a surface on an object in contact with it. It's a reaction force that acts to prevent the object from passing through the surface.
* Direction: The normal force always acts perpendicular to the surface, which means it's at a 90-degree angle to the surface.
* Upward examples: In many situations, the surface is horizontal (like the ground), so the normal force acts upward, opposing the force of gravity. This is what keeps us from falling through the floor!
* Other directions: If the surface is inclined, the normal force will be perpendicular to the incline. If an object is pressed against a wall, the normal force will be horizontal, acting outward from the wall.
In summary: The normal force always acts perpendicular to the surface of contact, and its direction can vary depending on the orientation of the surface.
