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23 Cards in this Set
- Front
- Back
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simple machine
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a device with few, if any, moving parts that makes it easier to do work
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mechanical advantage
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the number of times a simple machine multiplies an effort force.
is calculated by dividing the output force by the effort force |
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2 main classes of simple machines
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lever and inclined plane
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lever
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simple machine consisting of a rigid bar and a pivot point
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fulcrum
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the pivot point of a lever
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effort arm
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the part of the bar on which a person applies and effort force while using a lever
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resistance arm
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the portion of the bar on which the lever produces an output force
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first class lever
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fulcrum is between the effort force and the output force.
used to change the direction of the effort force |
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second class lever
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output force is between the effort force and the fulcrum
allows larger loads to be lifted |
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third class lever
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effort force is between the output force and fulcrum.
always produces an output force that is less than the effort force |
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wheel and axle
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simple machine that is a type of first class lever
usually consists of a wheel that applies an effort force and a smaller axle that produces the output force |
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pulley
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grooved wheel that turns by the action of a rope in the groove
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fixed pulley
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the wheel is attached to a fixed support
makes work easier by changing the direction of the effort force |
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movable pulley
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the wheel is attached to the object being lifted and moves with it
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pulley system
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made up of several pulleys working together
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inclined plane
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straight, slanted surface that can multiply an effort force
makes it easier to move a heavy load upward |
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screw
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an inclined plane wrapped around a central bar
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threads
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spiral ridges that move into an object as the head of a screw turns
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pitch
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the space between the threads of a screw
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wedge
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an inclined plane that changes the direction of an applied effort force
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compound machine
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a combination of two or more simple machines
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efficiency
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the ratio of the work done by a machine to the work that was put into it
to calculate, divide the output work by the effort work |
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oil
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a substance that can be put onto certain parts of a machine that helps to reduce friction, therefore increasing efficiency
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