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Free-Body Diagram Builder
Pick a force, then pick its direction. Add every force acting on the object, and nothing else. Then press Check.
Situations (green = done)
1 · Choose a force
2 · Which way does it point?
Forces on your diagram (tap to remove)
3 · What is the direction of the NET force?
Rules for every free-body diagram
- Weight (mg) always points straight down. Everything near Earth has it.
- Normal force (N) comes from a surface the object touches. It is perpendicular to the surface, pushing away.
- Tension (T) comes from a rope or string. It pulls along the rope, away from the object.
- Friction (f) comes from a rough surface. It is parallel to the surface and opposes sliding (or the tendency to slide).
- Air resistance (D) opposes the velocity. Applied force (F) is a push or pull by a person or thing.
- No agent means no force. There is no "force of motion". A moving object keeps moving by inertia (First Law).