For an object at rest, the normal force equals the gravitational force. What is the sum of these forces called?

The sum of all forces on an object is called the "net" force on it.

For an object at rest, we call that sum of forces "zero".

Sum of these forces is called net force.

Explanation:

An object is placed on the surface of Earth. The forces acting on it are normal force and the gravitational force. The gravitational force is given by:

W = F = mg

g is the acceleration due to gravity

m is the mass of the object

A force that act on the object to balance the gravitational force is called the normal force. The net force is the vector combination of all the forces acting on the object. So, the sum of these forces is called net force.