However, forces that the object exerts on its environment must not be included. With the exception of gravity, all of the forces we have discussed require direct contact with the object. Do not include the net force on the object.
Consider the types of forces described in Common Forces-normal force, friction, tension, and spring force-as well as weight and applied force. We often place this point at the origin of an xy-coordinate system. If you are treating the object as a particle (no size or shape and no rotation), represent the object as a point. At first, you may want to draw a circle around the object of interest to be sure you focus on labeling the forces acting on the object. Observe the following rules when constructing a free-body diagram: Problem-Solving Strategy: Constructing Free-Body Diagrams
