 | A machine helps us to accomplish a task by changing the direction and/or magnitude of the force we apply. All the constituent parts of machines fall into six categories of simple machines: levers, pulleys, wheels and axles, ramps, wedges, and screws. A compound machine, such as a bicycle or the human leg, is composed of two or more simple machines that work together. Real-world machines have an efficiency of less than 100% because some of the input work is lost to friction.
|  | | By the end of this chapter you should be able to
|  | define mechanical advantage, ideal mechanical advantage, and efficiency of a machine;
| | describe the six types of simple machines;
| | calculate the mechanical advantages of each type of simple machine; and
| | define a compound machine, calculate its total mechanical advantage, and provide several examples.
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|  | 12A: Levers
12B: Pulleys
12C: Ramps and inclined planes
Design project: Wind power
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