Free body diagrams
A free body diagram is the first thing drawn in any statics problem and the last thing checked when the answer looks wrong. These six guides read in order: what one is, how to draw it, what goes on it, what usually goes wrong, and how to turn the finished sketch into equations.
The guides
What Is a Free Body Diagram?
A free body diagram (FBD) is a sketch showing all forces acting on an object. Learn what FBDs are, why they matter, and see simple examples.
How to Draw a Free Body Diagram in 6 Steps
Learn how to draw a free body diagram step by step: isolate the body, add weight, normal, friction, and tension forces, choose axes, and check your work.
Types of Forces in Free Body Diagrams
Every force you'll meet in a free body diagram: weight, normal force, friction, tension, spring force, applied loads, and drag — with direction rules for each.
Types of Supports and Their Reactions
Pin, roller, fixed, and hinge supports explained — how many reactions each provides, how to draw them in a free body diagram, and how to count unknowns.
10 Common Free Body Diagram Mistakes (And How to Fix Them)
The 10 most common free body diagram mistakes students make — from missing friction to inventing centrifugal forces — with a quick fix for each one.
From Free Body Diagram to Equations
Turn a free body diagram into solvable equations: choosing axes, resolving components, writing ΣF=0 and ΣM=0, and picking smart moment points.
Draw one while you read.