Free-body force diagrams, sometimes referred to as "force diagrams" or "free-body diagrams," are important in understanding the role forces play when thinking about the laws of motion.

Interactive popup. Assistance may be required. There is more than one force acting upon the object including gravity, force of engines, and friction.

Interactive popup. Assistance may be required. There is more than one force acting upon the object including gravity, force the girl’s mass, and friction.

Interactive popup. Assistance may be required. There is more than one force acting upon the object including gravity and the upward force of the rock below.

Force diagrams are used in all contexts of daily life from understanding how an airplane is kept in the air to understanding the role of gravity in the formation of land features and structures. When engineers design roads for cars or pathways for skaters, they must consider the forces involved with the movement that will be occuring on the road or path.

Free-body force diagrams provide a visualization of all of the forces acting on an object. In the following sections, you will look at a variety of objects in how force interaction is represented, developed, and interpreted.