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Chapter 11 Test
N/A
29
Science
8th Grade
04/08/2010

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Cards

Term
What is work?
Definition
The force exerted on an object that causes it to move.
Term
How is work calculated?
Definition
work=force x distance
Term
What is the metric unit for work?
Definition
Joules (J) = 1N/1s
Term
When does work occur?
Definition
Work occurs on an object when the object moves in the same direction in what the force is exerted.
Term
What are the 6 types of simple machines?
Definition

1. inclined plane

2. wedge

3. screw

4.lever

5.wheel and axle

6.pulley

Term
What is an example of each of the six simple machines?
Definition

inclined plane:stairs

wedge:zipper

screw:jar lid

lever:baseball bat

wheel and axle:car

pulley:crane

Term
What is power?
Definition
The rate at which work is completed
Term
How is power calculated?
Definition
power= work / time
Term
What is the metric unit for power?
Definition
Watt (W) = 1J/s
Term
What is a machine?
Definition
an instrument that allows work to be done in an easier way
Term
Explain first, second, and third class levers.
Definition

1st: fulcrum in middle

2nd: resistance in middle

3rd: effort in middle

Term
Give an example of first, second, and third class levers.
Definition

1st: see saw

2nd: wheel barrow

3rd:baseball bat

Term
What is a compound machine?
Definition
a machine made of two or more simple machines
Term
What are three effects that machines can have on work?
Definition

1. change the force

2. change the distance

3. change the direction

Term
What is mechanical advantage?
Definition
The number of times a machine increases a force exerted on it
Term
Can mechanical advantage ever be 100%?
Definition
No, because of friction
Term
How do you calculate efficiency?
Definition
efficiency= output work / input work x 100
Term
What is ideal mechanical advantage?
Definition
a machine with an efficiency of 100%
Term
What is actual mechanical advantage?
Definition
a machine with an efficiency that is less than 100%
Term
What does it mean if mechanical advantage is equal to 1?
Definition
the output force is equal to the input force
Term
What does it mean if mechanical advantage is less than 1?
Definition
the output force is less than the input force
Term
What does it mean if mechanical advantage is greater than 1?
Definition
The output force is greater than the input force
Term
What is a fulcrum?
Definition
the fixed point around which a lever pivots
Term
How is a screw like an inclined plane?
Definition
a screw is an inclined plane wrapped around a post
Term
How is a wedge like an inclined plane?
Definition
a wedge is an inclined plane that moves
Term
What is input force?
Definition
the force you exert on a machine
Term
What is output force?
Definition
the force the machine exerts on an object
Term
[image]
Definition
3rd class lever
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