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Simple MachinesNovember 24th-25th

Goal:

I will be able to explain the relationship between mass, force and distance traveled.

I will be able to describe the difference between different simple machines.

What makes something a simple machine?

Simple machines make work easier! A simple machine has few or no moving parts.

Simple machines make work easier by changing the amount of force applied, the direction of the force or both.

What exactly is work?

Work is done when a force moves an object over a distance.

Work requires movement of an object so if you push the desk and it does not move even though you are putting in a great deal of effort and applying force no work has been done.

Graphic Organizer

We will need 7 pieces of paper

We are going to make a flip chart to record the different kinds of simple machines.

Bill Nye: simple machines levers!

http://www.neok12.com/video/Simple-Machines/zX7a7d457d065b790405707f.htm

Levers

Rigid bars that pivot around a point

Change the direction of the force, change the ratio of the force and the distance an object move or both.

Types of Levers

First Class:

the fulcrum is between the effort ( the force that is applied to the lever) and the load (the force that works against the effort)

Examples include: seesaws, crowbars, and fingernail clippers

Second Class Levers

The load is placed between the fulcrum and the effort force.

The lever increases the force but does not change its direction Examples: wheelbarrows, nutcrackers

Third Class Levers

The effort is applied between the fulcrum and the load. This is the only type of lever that always reduces the effort force instead of increasing it. Examples: chopsticks, fishing rod, shovel, stapler,

tweezers

Wheel and Axels

The wheel and axel started being used around 3300 BC.

Changes the amount of force applied to an object. Used to steep a struck, open a valve on a water pipe, seal

a submarine hatch. The wider the wheel the less effort it takes to turn it. This

also means that you will need to turn the wider wheel a greater distance to do the same amount of work.

Wheel and axel

Pulleys

A pulley is a wheel with a groove along its edge.

A single fixed pulley consists of a pulley attached to a high point, with a rope fed through the wheel groove. It is called a fixed pulley because the pulley remains in place.

Fixed Pulley: Changes the direction of the force needed to move an object, but not the amount of force needed.

Pulley System

Combine two or more pulleys together. The more ropes supporting the load the less force you need to lift the load and the more rope you need to pull through.

pulleys

https://www.youtube.com/watch?v=LiarGb_LK10

Brain Pop Videos on Pulleys, wheel and axels,

and levers

Levers:https://www.brainpop.com/technology/simplemachines/levers/

Wheel and Axels:https://www.brainpop.com/technology/simplemachines/wheelandaxle/

Pulleys:https://www.brainpop.com/technology/simplemachines/pulley/

Workbook Pages

Pages: 228-232

Inclined Planes

Decreases the amount of force required to raise an object.

Why use an inclined plane? By pushing the object on an angle, the force needed

to oppose gravity is less.

Inclined planeshttps://www.youtube.com/watch?v=Zj_iWiXUZX8

Wedges and Screws

A wedge is a simple machine that consists of two inclined planes back to back.

A wedge changes the direction of the force.

A screw is an incline plane wrapped around a cylinder or cone. The screw changes both the direction of the force and the ratio of the force

Wedgehttp://mocomi.com/wedge/

Screwhttps://www.youtube.com/watch?v=dDEhrpFb1BU&src_vid=4oPPQpF7bHY&feature=iv&annotation_id=annotation_2624978011

Car jacks are an exampleLight bulbs screw into lampsToothpaste caps Jar lids

Compound machines

Tools that are made of a combination of simple machines are called compound machines.

Scissors: pair of levers with a fulcrum in the middle and the blade is a wedge.

Bicycle: pedals are levers and the sprocket is a wheel and axle

Compound machines

Workbook Pages

Pages: 233-235