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SCIENCE JOURNAL, WEEK #10, Tuesday, Nov. 1 Students’ Objectives Obj. 6.02 Analyze simple machines ESSENTIAL QUESTIONS, quotations, & vocabulary

EQ: What is a simple machine? Quotation: “The sleeping fox catches no poultry.”—Benjamin Franklin

Announcements, Questions???, Review

New Procedure—Binder Up can replace hand. Use it today. Class work assignment in journal? YES

Teacher presents. Frayer diagrams—instructions for simple machines

Students do.

CWiJ—Make Frayer Diagrams for 5 machines (Use the information provided. Follow instructions—two diagrams per page)

Homework ► Revise journal. Box final answer to EQ.

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PROCEDURES

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What is this for?

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Can you do this instead?

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If you do this

instead of this ,

you can continue your work while you wait for me.

Do this today and at other times when you must wait.

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•Got it?

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• Share information at your table.• Create your own Frayer diagrams in

your own journal.

• 2 Frayer diagrams per page.

• USE THE RESOURCES AT YOUR TABLE to find out more, and to help you if you get stuck.

• (e.g. Your resources tell all you need to know to start learning about mechanical advantage.)

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Copy this template for a Frayer diagram.

Topic by your name

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FIRST ASSIGNMENTUse the notes provided to make n Frayer diagrams to tell about any n of the following topics. n = ___

•Inclined Plane

•Wedge

•Screw

•Lever

•1st Class Lever

•2nd Class Lever

•3rd Class Lever

• Wheel and Axle

•Pulley

•Fixed Pulley

•Movable Pulley

•Block and Tackle

•Simple Machines in Your Body

•Compound Machines

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Make a Frayer Diagram Inclined Plane• A flat, sloped surface• aka: ramp• How it works: allows you to exert your input force

over a longer distance, thus decreasing input force• Input force – force with which you push or pull the

object• Output force – force that you would have needed to

just lift the object• MA = length of incline/height of incline• The longer the incline, the less input force you

need• fD Fd

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Make a Frayer Diagram Wedge• A device that is thick at one end and tapers to a

thin edge at the other end• One or two inclined planes put together• Most often used to cut things• How it works: you move the wedge toward the

object, input force pushes wedge into object and the output force is the wedge exerting force on the object (e.g. chopping wood)

• MA = length of wedge/width of wedge• The longer and thinner the wedge, the greater its

MA• fD Fd• Examples: hand-held pencil sharpener, shovel

blade, knife

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Make a Frayer Diagram Screw• An inclined plane wrapped around a cylinder

(spiral forms threads of screw)• How it works: twist a screw into wood (input

force), the threads increase the distance over which the input force acts, the threads exert an output force on the object, friction holds the screw in place

• Input force is decreased by the threads• MA = length around threads/length of screw• The closer together the threads, the greater the

MA• fD Fd• Examples: bolts, light bulbs, jar lids, some pumps

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Make a Frayer Diagram Lever• A rigid bar that is free to pivot, or rotate, on a fixed

point (fulcrum)• How it works: you exert an input force on one part

of the bar and the other part of the bar exerts an output force on an object (opening a paint can)

• MA = input arm length/output arm length• Input arm length – distance from fulcrum to input

force• Output arm length – distance from fulcrum to

output force• Levers can increase/decrease your input force and

decrease/increase the output distance• Classes of levers – according to the location of the

fulcrum relative to input and output forces

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Make a Frayer Diagram – First class lever

• Changes direction of input force • f and d stay same if fulcrum is in center• Can decrease input force if fulcrum is

closer to output force (e.g. paint-can opener)

• Can increase input force if fulcrum is farther from output force

• Ex: paint-can opener, scissors (2), pliers (2), seesaw

• fD Fd

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Make a Frayer Diagram – Second class lever

• Does not change the direction of the input force

• Increases output force• Ex: wheelbarrow, door, nutcrackers

(2), bottle openers – (Wheelbarrow also has a wheel and axle.)

• fD Fd

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Make a Frayer Diagram – Third class lever

• Does not change the direction of the input force

• Increases output distance• lever is attached to fulcrum• Ex: hockey stick, fishing pole, baseball

bat, catapult• Fd fD

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Make a Frayer Diagram Wheel and Axle• Simple machine made of two circular or cylindrical objects

fastened together that rotate about a common axis• Object with larger radius wheel• Object with smaller radius axle• How it works: apply input force to wheel, axle rotates and

exerts output force• Increases force, but you must exert your force over a larger

distance• fD Fd• Ex: doorknob, steering wheel, screwdriver• Reverse:

– Apply input force to axle (Fd fD)– Ex: transportation vehicles (cars, bicycles)

• MA = radius of wheel/radius of axle• The greater the difference between the wheel and axle, the

greater (or if reverse situation, lesser) the MA

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Make a Frayer Diagram

Pulley• A simple machine made of a grooved

wheel with a rope or cable wrapped around it

• How it works: you pull on one end of the rope (input force), the other end of the rope pulls on the object (output force)

• Can decrease amount of input force needed (fD Fd)

• Can change the direction of input force (d and f stay same)

• Types of pulleys

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Make a Frayer Diagram – Fixed Pulley

• Pulley is attached to a structure (pulley does not move)

• Only changes the direction of the force

• F and D do not change• MA = 1

• Ex: flagpole, weightlifting machine

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Make a Frayer Diagram – Movable Pulley

• Pulley is attached to the object you want to move (pulley moves along rope/cable with the object)

• Decreases input force needed (fD Fd)

• MA = number of supporting strands• Ex: pulleys on sailboats

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Make a Frayer Diagram – Block and Tackle

• Combines fixed and movable pulleys• Decreases input force needed (fD

Fd)• MA = number of supporting strands• Ex: construction crane

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Make a Frayer Diagram

Simple Machines in the Body• Most are levers made of bones and

muscle• Muscles pull on bones (input force), joint

is fulcrum, output force is used for doing work like lifting your hand

• Wedges – your teeth and fingernails

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Make a Frayer Diagram

Compound Machines• A machine that utilizes two or more

simple machines• MA = product of MAs of individual

simple machine parts• Most machines are compound, e.g. apple

peeler, pencil sharpener, bicycle, wheelbarrow, tweezers, scissors

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