Introduction

Free Body Diagrams (FBDs) are a pictorial representation of all of the external forces on an object. It starts as a simple dot representing your system. Then all of the forces are drawn, including relative size and direction. An axis must also be included to indicate which direction(s) are positive. Also, if a tilted axis is appropriate, such as in Inclined Planes then the tilted axis should be included as well as all relevant angles.
 

Two objects in space, FBD fundamentals

 
Book on a scale on the Earth, FBD's and the 3rd law
 
 
Notes and clicker questions
 
 

Key Terms

Text/Videos

This is a concise description of free body diagrams;

Here is a chapter from the OpenStax textbook related to free body diagrams;

Follow along in this interactive tutorial by W.W. Norton & Company about FBD;

Simulations

This PHet simulation allow you to view changing magnitudes of the force vectors in a FBD;

Additional Studying/Review

  • This is a link to an interactive slideshow with an introduction to FBD as well as a step by step tutorial; FBD Slideshow.
  • PhysicsLab Free Body Diagrams
  • If you still have any doubts about FBD and also need a little more info on the types of forces we are dealing with watch this video;