4.2 FREE BODY DIAGRAMS (FBD)
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Up to this point we assumed very simple forces acting on very small particles.
In reality mechanical systems have many parts, and we draw an FBD for each part.
We should divide forces on free body diagrams into two categories,
Internal - these forces act only within a free body, and cancel out, unless we are looking at a section of a free body.
External - these forces act on a free body, and they induce reaction forces. Examples are gravity, and other free bodies.
An example of using free body diagrams for a system is given below with a system of masses, ropes, pulleys and anchors.
4.2.1 Pulleys and Springs
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Pulleys are basically a wheeled roller that a rope can roll over freely,
A simple example of a pulley used for lifting a mass is given below,
Springs are a very important engineering tool,
A sample problem that uses springs is given below, ([Hibbeler, 1992] prob 3-16, pg. )
4.2.2 Summary
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equilibrium of forces and moments
free body diagrams (FBD's)
