In physics, a free body is an object that is isolated from its surroundings and is subject to forces. A free body diagram (FBD) is a graphical representation of the forces acting on a free body. It is a pictorial device used by physicists and engineers to visualize the applied forces, moments, and resulting reactions on a body in a given condition .
A free body diagram is a special example of the vector diagrams that were discussed in an earlier unit. These diagrams will be used throughout our study of physics. Free-body diagrams are diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation. The size of the arrow in a free-body diagram reflects the magnitude of the force. The direction of the arrow shows the direction that the force is acting. Each force arrow in the diagram is labeled to indicate the exact type of force. It is generally customary in a free-body diagram to represent the object by a box and to draw the force arrow from the center of the box outward in the direction that the force is acting .
Free-body diagrams are an essential tool in physics. They are used to analyze the forces acting on an object and to determine the net force acting on the object. The net force is the vector sum of all the forces acting on the object. If the net force acting on an object is zero, then the object is said to be in a state of equilibrium. If the net force acting on an object is not zero, then the object will experience an acceleration in the direction of the net force .
Free-body diagrams are used in many areas of physics, including mechanics, electromagnetism, and thermodynamics. They are used to analyze the forces acting on objects in motion, the forces acting on objects at rest, and the forces acting on objects in equilibrium. Free-body diagrams are also used to analyze the forces acting on systems of objects, such as pulleys, inclined planes, and springs .
In summary, a free body is an object that is isolated from its surroundings and is subject to forces. A free body diagram