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Simple MachinesSimple MachinesTypesTypes

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Simple MachinesSimple Machines The six simple machines are:The six simple machines are:

Lever Lever Wheel and Axle Wheel and Axle Pulley Pulley Inclined Plane Inclined Plane Wedge Wedge Screw Screw

All simple machines are variations of the All simple machines are variations of the lever and the inclined planelever and the inclined plane

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The LeverThe Lever A lever is a bar that rotates A lever is a bar that rotates

around a fixed point called around a fixed point called the fulcrum.the fulcrum.

The bar may be either The bar may be either straight or curved.straight or curved.

In use, a lever has both an In use, a lever has both an effort (or applied) force effort (or applied) force and a load (resistant and a load (resistant force). force).

The distance from fulcrum The distance from fulcrum to where the effort force is to where the effort force is applied= effort armapplied= effort arm

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The 3 Classes of LeversThe 3 Classes of Levers

The class of a lever The class of a lever is determined by is determined by the location of the the location of the effort force and the effort force and the load relative to the load relative to the fulcrum. fulcrum.

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To find the MA of a lever, divide the output force by the input force, or divide the length of the resistance arm by the length of the effort arm.

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First Class LeverFirst Class Lever

fulcrum is located at some point fulcrum is located at some point between the effort and resistance between the effort and resistance forces.forces. Common examples of first-class levers Common examples of first-class levers

include crowbars, scissors, pliers, tin include crowbars, scissors, pliers, tin snips and seesaws. snips and seesaws.

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Fulcrum is between EF (effort) and RF (load)Fulcrum is between EF (effort) and RF (load)Effort moves farther than Resistance.Effort moves farther than Resistance. Multiplies EF and changes its direction Multiplies EF and changes its direction

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Second Class LeverSecond Class Lever

the load is located between the fulcrum the load is located between the fulcrum and the effort force.and the effort force.

Common examples of second-class levers Common examples of second-class levers include nut crackers, wheel barrows, include nut crackers, wheel barrows, doors, and bottle openers.doors, and bottle openers.

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RF (load) is between fulcrum and EF RF (load) is between fulcrum and EF Effort moves farther than Resistance.Effort moves farther than Resistance.

Multiplies EF, but does not change its directionMultiplies EF, but does not change its direction

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Third Class LeverThird Class Lever

the effort force is applied between the effort force is applied between the fulcrum and the resistance force.the fulcrum and the resistance force. Examples of third-class levers include Examples of third-class levers include

tweezers, hammers, and shovels.tweezers, hammers, and shovels.

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EF is between fulcrum and RF (load) EF is between fulcrum and RF (load) Does not multiply force Does not multiply force

Resistance moves farther than Effort.Resistance moves farther than Effort.

Multiplies the distance the effort force travelsMultiplies the distance the effort force travels

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PulleyPulley A pulley consists of a grooved wheel A pulley consists of a grooved wheel

that turns freely in a frame called a that turns freely in a frame called a block.block.

A pulley can be used to simply change A pulley can be used to simply change the direction of a force or to gain a the direction of a force or to gain a mechanical advantage, depending on mechanical advantage, depending on how the pulley is arranged. how the pulley is arranged.

Fixed PulleyFixed Pulley it does not rise or it does not rise or

fall with the load fall with the load being moved. being moved.

A fixed pulley A fixed pulley changes the changes the direction of a force; direction of a force;

does not create a does not create a mechanical mechanical advantage. advantage.

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Moveable pulleyMoveable pulley rises and falls with rises and falls with

the load that is being the load that is being moved. moved.

creates a mechanical creates a mechanical advantage; advantage;

it does not change it does not change the direction of a the direction of a force. force.

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Block and tackleBlock and tackle

Consists of fixed Consists of fixed and moveable and moveable pulleys. Can have pulleys. Can have a large mechanical a large mechanical advantage.advantage.

Changes direction Changes direction and gains force and gains force

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Wheel and AxleWheel and Axle The wheel and axle is The wheel and axle is

a simple machine a simple machine consisting of a large consisting of a large wheel rigidly secured wheel rigidly secured to a smaller wheel or to a smaller wheel or shaft, called an axle. shaft, called an axle.

When either the wheel When either the wheel or axle turns, the or axle turns, the other part also turns. other part also turns. One full revolution of One full revolution of either part causes one either part causes one full revolution of the full revolution of the other part. other part.

gearsgears

Has 2 wheels of Has 2 wheels of different sizes with different sizes with interlocking teeth. interlocking teeth. When one wheel is When one wheel is turned, the other turned, the other turnsturns

Gears may change Gears may change the direction of the the direction of the force. An example force. An example is a can opener- as is a can opener- as you twist the you twist the handle in one handle in one direction, the can direction, the can revolves in the revolves in the opposite direction.opposite direction.

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Inclined PlaneInclined Plane

An inclined plane is An inclined plane is an even sloping an even sloping surface. The surface. The inclined plane inclined plane makes it easier to makes it easier to move a weight move a weight from a lower to from a lower to higher elevation.higher elevation.

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Although it takes less force for car A to get to the top of the ramp, Although it takes less force for car A to get to the top of the ramp, all the cars do the same amount of work.all the cars do the same amount of work.

A B C

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ScrewScrew

Threads form a tiny Threads form a tiny ramp that runs ramp that runs upward from its tip. upward from its tip. As you turn the As you turn the screw, the plane screw, the plane slides through the slides through the woodwood

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WedgeWedge The wedge is a modification The wedge is a modification

of the inclined plane. of the inclined plane. Wedges are used as either Wedges are used as either separating or holding separating or holding devices. devices.

A wedge can either be A wedge can either be composed of one or two composed of one or two inclined planes. A double inclined planes. A double wedge can be thought of as wedge can be thought of as two inclined planes joined two inclined planes joined together with their sloping together with their sloping surfaces outward. surfaces outward.

The wedge changes the The wedge changes the direction of the effort forcedirection of the effort force