Question

What is free body diagram ?

How many force can be in free body diagram?

Answer 1

Free-body diagrams are diagramsused to show the relative magnitude and direction of all forces acting upon an object in a given situation. A free-body diagram is a special example of the vector diagrams that were discussed in an earlier unit. ... The direction of the arrow shows the direction that the force is acting.
Or
free body diagram (force diagram, or FBD) is a graphical illustration used to visualize the applied forces, movements, and resulting reactions on a body in a given condition. They depict a body or connected bodies with all of the applied forces and moments, as well as reactions, that act on that/those body(ies). The body may consist of multiple internal members, for example, a truss, or be a compact body such as a beam. A series of free bodies and other diagrams may be necessary to solve complex problems.
no of force in a free body diagram is depends on a situvation.
for example in given condition frictional force become considerable then our free body diagram have must be frictional force component.otherwise there have no component of frictional force.