Final answer:
A free-body diagram is a graphical tool used to visualize all the external forces acting on an isolated object or system, represented as vectors. It is used to analyze the forces and does not include internal forces, acceleration, or velocity.
Step-by-step explanation:
The question refers to the definition and purpose of a free-body diagram. A free-body diagram is a graphical illustration used to visualize all the external forces acting upon a single object or system. In such a diagram, the object is typically represented by a point, and the forces are depicted as vectors extending outward from this point. It’s crucial to note that the diagram only includes external forces; internal forces are not represented because they are equal and opposite and cancel each other out, thus having no effect on the motion of the object according to Newton’s third law of motion.
Only the forces are represented in a free-body diagram, which means it does not include acceleration or velocity of the object. The primary purpose of a free-body diagram is to analyze the forces acting on a system, which makes it a fundamental tool in the study and application of Newton's laws of motion. These diagrams are especially helpful in determining the resultant force acting on the object and in understanding how these forces will affect the object's motion.