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Simple Machines and Equilibrium
A basketball player couldn't control his saliva but he could sure dribble.
Monday, October 29, 2012 Simple Machines 2
Simple Machines
¢ A simple machine is a collection of elements connected together that function to transfer forces
¢ You need to remember that all the parts of a simple machine are in equilibrium
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Simple Machines
¢ Unlike trusses, all of the members of a simple machine will not be two-force members and therefore a more detailed analysis will be necessary
¢ If you will just remember to utilize the connections and their reaction along with knowing that a FBD of each part of the machine may be necessary
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Simple Machines
¢ The best way to illustrate the analysis is through examples
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Frames
¢ Is a system of stationary members used to support loads
¢ Not the same as a truss because all the members are not two-force members
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Frames – Example 6.9
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Frames – Example 6.9
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Frames – Example 6.9
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Frames – Example 6.9
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Pulleys
¢ In these type of problems, you need to remember that the same rope will always carry the same amount of force
¢ The only time that the force changes in a rope is when it is tied to some point (then it actually become two different ropes)
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Pulleys – Example 6-10
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Pulleys – Example 6-10
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Pulleys – Example 6-12
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Pulleys – Example 6-12
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Pulleys – Example 6-12
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Problems
¢ Problem 6-68 ¢ Determine the
force P needed to hold the 20-lb block in equilibrium.
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Problems
¢ Problem 6-78 ¢ Determine the
horizontal and vertical components at C which member ABC exerts on member CEF.
Homework
¢ Problem 6-62 ¢ Problem 6-63 ¢ Problem 6-64
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