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LeversJason Day

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A lever is an object consisting of a rigid bar

or plank that pivots at a certain point.

Often used to lift an object at a second

point when applying force to a third point.

What is a lever?

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Picture

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The first point (where the bar or plank pivots) that is called the “fulcrum.”

The second point (the fraction of the bar or plank holding up the object that is to be lifted) is called the “resistance arm.”

The third point (the fraction of the bar or plank that force is applied to) is called the “effort arm.”

Parts

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PictureResistance Arm Effort Arm

Fulcrum

Object

Bar or Plank

Applied Force

Pivot

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How to Calculate Mechanical Advantage

MA= Effort Arm/Resistance Arm

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Pictures and Stuff

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3

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MA = 3

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MA = .4

MA = 2.6-

MA = 1

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Mechanical advantage is the ratio of output force to the input force.

It is used to calculate the efficiency of a machine.

The higher the number the more efficient the machine is. The lower the number the less efficient the machine is.

What is Mechanical Advantage?

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There are three different types of levers. A first class-when the fulcrum is in between

the where the force is applied and the object or load.

A second class-when the object or load is in between the pivot and where the force is applied.

A third class-when the point at which the force is applied is between the object or load and the pivot.

Types of Levers

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Pictures

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A see saw

A pair of scissors

Pliers

Examples of a First Class Lever

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A stapler

A wheel barrow

A nail clipper

Examples of a Second Class Lever

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Tweezers

Fishing Rod

Tongs

Examples of a Third Class Lever

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Levers are used to move object. Usually. Levers can be found in many different

places. To calculate Mechanical Advantage of a

lever you divide the length effort arm from the length resistance arm. (see page 6)

There are different of levers. First Class, Second Class, and Third Class. (see pages 10-13)

Recap