Chapter 6 Summary

• a simple machine changes the direction and/or magnitude of a force. It does not change the amount of work that is done.
• With zero energy losses, the work done on one side of a simple machine will equal the energy gained at the other side of the machine. 
• The work or energy that comes out of a machine can never exceed the work or energy that goes into a machine. 

There are two main families of Simple Machines: 

• Inclined Plane Family 

                Ramp, Wedge, Screw 

• Lever Family 

                Levers (3 classes), Wheel and Axle, Pulley 

• The Mechanical Advantage (MA) of a Simple Machine is the "advantage" that one gets from using the machine. Usually it is a force multiplier. If a machine has an MA of 5, it means you can lift 5X more force. Of course, you will have to also use 5X more distance. 
• The 3 classes of Levers are differentiated by the positioning of the fulcrum, ef­fort force, and load force. 
• In reality, no machine is ever 100% efficient. The efficiency of a machine is a ratio between the work output of a machine divided by the work input of a ma­chine. 
  

Equations 

• Mechanical Advantage (MA) = load force / effort force = effort distance / load distance 
  

                MA = FL/Fe = de/dL 

• Efficiency = work (or energy) out / work (or energy) in