Levers

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Definition

• A board or bar that rests on a turning point called the fulcrum, used to change the amount, the strength and the direction of movement.

http://www.cool-science-projects.com/images/man-and-lever.jpg

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• An object that a lever moves is called the load or load force. 

• The force used to move a lever is called the effort force.

http://currentreports.info/wp-content/uploads/2009/02/firce_class_lever_drawing1.gif

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• The position of the effort force and the load can be changed by moving them to different points on the lever.

• The closer the load force is to the fulcrum, the easier it is to move.

Effort Force The load forceis easier to lift because it is closer to the fulcrum

http://library.thinkquest.org/C004451F/firstclasslever1.gif

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1st Class or Class 1 Lever• The load force and

the effort force are separated by the fulcrum

• As one moves up the other moves down.

• The amount and the strength of the movement is depends on the distance from the fulcrum

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1st Class Levers

http://www.worsleyschool.net/science/files/lever/firstexample.JPGhttp://www.professorbeaker.com/images/levers2.gifhttp://www.constructionknowledge.net/general_technical_knowledge/images_gen_tech_knowledge/lever%20figure%201_3.gif

LOAD

http://shadowwar.files.wordpress.com/2009/06/see-saw1.jpg

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2nd Class or Class 2 Lever• The load force is

between the effort force and the fulcrum.

• This lever uses mechanical advantage to make moving large weights easier.

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2nd Class Levers

http://www.professorbeaker.com/images/levers2.gif

http://library.thinkquest.org/C004451F/secondclasslever2.jpg http://www.cdxetextbook.com/images/leveradvantage_02.jpg

http://www.factmonster.com/images/ency196levers002.jpg

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3rd Class or Class 3 Lever

• The effort force is between the fulcrum and the load.

• Mechanical advantage is reduced but more movement is possible.

http://www.hometrainingtools.com

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3rd Class Levers

http://www.personal.psu.edu/jlw1086/crosby.jpg

http://www.worsleyschool.net/science/files/lever/thirdexample.JPG

http://www.factmonster.com/images/ency196levers003.jpg

Effort

http://www.professorbeaker.com/images/levers2.gif

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Review: Classes of Levers

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First Class Second Class Third Class

Review: Classes of Levers

http://www.professorbeaker.com/images/levers2.gif

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