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.
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http://www.cool-science-projects.com/images/man-and-lever.jpg
• 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.
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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
Back
http://library.thinkquest.org/C004451F/firstclasslever1.gif
The load
force
is easier to
lift because
it is closer
to the
fulcrum
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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
Back movement is depends
on the distance from
the fulcrum
http://www.hometrainingtools.com
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1st Class Levers
Back
LOAD
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http://shadowwar.files.wordpress.com/2009/06/see-saw1.jpg
http://www.constructionknowledge.net/general_technical_knowledge/images_gen_tech_knowledge/lever%20figure%201_3.gif
http://www.professorbeaker.com/images/levers2.gif
http://www.worsleyschool.net/science/files/lever/firstexample.JPG
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.
Back
http://www.hometrainingtools.com
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nd
2
Class Levers
Back
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http://library.thinkquest.org/C004451F/secondclasslever2.jpg
http://www.cdxetextbook.com/images/leveradvantage_02.jpg
http://www.professorbeaker.com/images/levers2.gif
http://www.factmonster.com/images/ency196levers002.jpg
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.
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Back
http://www.hometrainingtools.com
rd
3
Class Levers
Effort
Back
http://www.professorbeaker.com/images/levers2.gif
http://www.factmonster.com/images/ency196levers003.jpg
http://www.worsleyschool.net/science/files/lever/thirdexample.JPG
http://www.personal.psu.edu/jlw1086/crosby.jpg
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Review:
Classes of Levers
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Review:
Classes of Levers
First Class
Back
http://www.professorbeaker.com/images/levers2.gif
Second Class
Third Class