Simple Machines

Simple Machines

• Wheel and axle• Pulley• Lever• Inclined plane• Wedge• Screw

Work• Work is the transfer of energy from one

system to another

• Mechanical work is the product of the magnitude of force in the direction of displacement and the distance through which a body moves

Displacement

Work

• Work indicates that a force is exerted and is moving something

• Simple machines make work easier

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart © iStockphoto

Wheel and Axle

• Two connected circular objects of different diameters

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Special Wheel and Axle

• Gear– Wheel with teeth– Teeth of one gear

push against teeth of another gear

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Pulley

• A wheel (and axle) with a rope running over it

Microsoft Office Clipart

Microsoft Office ClipartMicrosoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Pulley

• A pulley can change the direction of force

• Multiple pulleys in combination can reduce the effort force to move an object

10 lb 10 lb

10 lb

80 lb

10 lb

Lever

• A bar that is free to pivot around a fixed point

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Lever

• Three components– Resistance Force– Effort Force– Fulcrum

ResistanceEffort

Fulcrum

Lever• Three types

– First Class• Fulcrum between effort and resistance forces• Effort and resistance forces in same direction

Effort Resistance

Lever• Three types

– Second Class• Resistance force between fulcrum and effort force• Effort and resistance forces in opposing directions

Resistance

Effort

Lever• Three types

– Third Class• Effort force between fulcrum and resistance force• Effort and resistance forces in opposing directions

Resistance

Effort

Inclined Plane

• Slanted surface used to raise an object

© iStockphoto

© iStockphoto

Microsoft Office Clipart

Microsoft Office Clipart

Specialized Inclined Planes

• Wedge

• Screw

Images from Microsoft Office Clipart

Wedge

• Inclined plane that moves

• A triangle shape with a sharp point

• Can split, cut, tighten, or hold things together

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office Clipart

Microsoft Office ClipartMicrosoft Office Clipart

Screw

• Inclined plane wrapped around a shaft

• Used to fasten things together or move things

Corkscrew conveyor

Worm gear

Parking garage ramp© iStockphoto

© iStockphoto

© iStockphoto© iStockphoto

References

Microsoft, Inc. (2008). Clip art. Retrieved from http://office. microsoft.com/en-us/clipart/default.aspx

Wikipedia. Retrieved from http://en.wikipedia.org

iStockphoto. Retrieved from http://www.istockphoto.com/index.php