Final answer:
The normal force on a flat surface is calculated by N = mg, where N is the normal force, m is the mass, and g is the acceleration due to gravity. This force counteracts the object's weight and is also crucial in calculating friction.
Step-by-step explanation:
The formula for the normal force when an object is sitting on a flat, non-accelerating surface is given by N = mg, where N is the normal force, m is the mass of the object, and g is the acceleration due to gravity.
This means that the normal force is equal to the weight of the object.
Furthermore, when considering friction, it is important to remember that it is proportional to the normal force.