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CHAPTER 10

SIMPLEMACHINE

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10.1 Levers

Lever

- is a simple machine

- enables a small efort to overcomea heavy load

- can be used to lit heavy objects

- makes work easier

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A lever has three parts

- ulcrum !"# $ the turnin% point or pivot- efort ! $ the orce applied toovercome a resistin% orce called the load

- load !L# $ the resistin% orce e'erted byan object

Lever can be classi(ed into

- (rst class

- second class

- third class

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"irst class lever

"ulcrum is between the efort and theload

*mall efort is used to move a lar%eload

&fort is urther rom the ulcrumthan the load

&fort moves throu%h a lon%erdistance than the load

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*econd class lever

,he load is between the ulcrum andthe efort

*mall efort is used to move a lar%eload

&fort is urther rom the ulcrumthan the load is

&fort moves throu%h a lon%erdistance than the load

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,hird class lever

,he efort is between the ulcrumand the load

A lar%e efort is used to move a smallload

Load is urther rom the ulcrum thanthe efort is

,he load moves throu%h a lon%erdistance than the efort

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/hen we loosen a bolt usin% aspanner a orce that is applied has a

turnin% efect on the spanner ,his turnin% efect o a orce is known

as the moment o a orce

,he turnin% efect or moment o aorce is inuenced by

- the ma%nitude o the orce applied

- the position o the orce applied ,he *. unit or measurin% the

moment o a orce is newton-

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,he moment o a orce can be

calculated by usin% the ormulabelow

moment o a orce 5

orce ' perpendicular distance rom the pivot to theorce

,he principle o moment can be represented bythe ollowin% ormula

load ' 5 efort '

distance o load romthe ulcrum

distance o efort romthe ulcrum

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10.2 appreciatin% the innovative efort in

the desi%n o machines to simpliy work

7uman bein%s make use o the principleo lever to invent machines.

nnovative eforts in inventin% machines

make our work easier. 8omple' machines help us to carry out

di9cult and tedious work.

&'ample o some machines that can arebased on the principle o levers are cranetypewriter pedal bin and paper cutter.

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