Final answer:
People calculate net force and make force diagrams to predict and understand motion and changes in motion.
Step-by-step explanation:
People calculate net force and make force diagrams in order to predict and understand motion and changes in motion.
Net force is the vector sum of all the forces exerted on an object, and by calculating it, we can determine the resulting motion of the object.
Force diagrams, also known as free-body diagrams, visualize the forces acting on an object, helping us identify the net force and analyze the object's motion.