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UnitGrades 7 - 9

Simple Machines

More than 20 sketches of mechanical devices marked with distances, angles and variables, including wedges, pulleys and gears. Equation in large type floats above sketches: work = force x distance.Students investigate the six simple machines

Overview of topics by lesson: 1) work [as defined by physical science] and the mechanical advantages of six simple machines that make work easier, 2) more about the inclined plane, wedge and screw, including each machine's mechanical advantages and work = force x distance, 3) more about the lever, pulley, and wheel-and-axle, 4) introduction to compound machines including an examination of machine inventions and their place in our everyday lives, and 5) introduction to Rube Goldberg contraptions, known for making simple tasks more difficult to complete, as a way to engage students in critical thinking to evaluate everyday machines.

The fundamental mechanical devices that have come to be known as "simple machines" through the years are basic human inventions that help accomplish physical tasks through mechanical advantage. The same simple machines used by ancient engineers to build pyramids are employed by today's engineers to construct modern structures such as houses, bridges, roller coasters and skyscrapers. From everyday hand tools (crowbars, nails, wheels, ramps) to intricate "compound machines" that marry together many simple machines in endless combinations (pencil sharpeners, bicycles, elevators, medical devices, airplanes), engineers of all types continually work together to design better and more creative tools, devices, equipment and products of modern convenience that help people do more with less, incorporating the principles of simple machines.

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