In physics, what do we call the upward force exerted by surfaces that opposes an object's weight?

The upward force exerted by surfaces that opposes an object's weight is referred to as the normal force. This force acts perpendicular to the surface that an object is resting on. When an object is placed on a horizontal surface, the normal force balances the object's weight, which is the force due to gravity acting downward. This balance allows the object to remain at rest without accelerating vertically.

In scenarios where the surface is angled, such as on a slope, the normal force still acts perpendicular to the surface and adjusts based on the angle and weight of the object. Understanding the normal force is crucial in analyzing the motion and equilibrium of objects, as it is a fundamental concept in mechanics that helps explain how and why objects interact with surfaces.