Simple Machines

Group MM

PULLEY!

Definition Pulley is a simple machine that involves a

wheel, that holds a rope or line. It helps to spread out the weight to lessen the force needed and used so that more weight can be lifted

FixedPulley

Flat Pulley

FIXED PULLEY MOVABLE PULLEY COMBINED PULLEY

Mechanical AdvantageThe main advantage of a pulley (which was once said by Archimedes) is to lift heavier weight with less force.

Story Time“According to Plutarch, Archimedes had stated in a letter to King Hieron that he could move any weight with pulleys; he boasted that given enough pulleys he could move the world! The king challenged him to move a large ship in his arsenal, a ship that would take many men and great labor to move to the sea. On the appointed day, the ship was loaded with many passengers and a full cargo, and all watched to see if Archimedes could do what he said. He sat a distance away from the ship, pulled on the cord in his hand by degrees, and drew the ship along "as smoothly and evenly as if she had been in the sea." “http://www.swe.org/iac/lp/pulley_03.html

Best Mechanical Advantage The Mechanical Advantage is a ratio. The higher

the advantage the easier it is to lift the weight. Formula:

The easiest way to find mechanical advantage of a pulley is to count the number of ropes then subtract one. The reason you subtract one is because you never count the one you are pulling.

ex. Say there are 7 ropes7 – 1 (the one you are pulling) = 6therefore the mechanical advantage is 6

Compound Machine

Levers

Wheel and Axle

Pulley

Screw

Wheel and Axle

Pulley

Screw

Wheel and Axle

Pulley

Screw

By Kimmy Gardyasz

The Screw is…

• The screw is an inclined plane wrapped around a shaft. This form of inclined is helical. It has a rounded head at the top, from which the screw can be rotated to be tightened or loosened.

• A screws’ function can include holding things together and raising/lowering things.

Mechanical Advantage

• MA=Distance over which effort is applied/distances over what the load is moved is the basic equation basis for simple machines in general.

• To find the mechanical advantage of a screw you can take the pitch* of the screw divided by its circumference.

• *the pitch is the length of one screw thread (or end) to another.

Finding mechanical advantage (example)

• Find the mechanical advantage of a screw that is 5 cm in length (pitch) and a 2 cm circumference.

• 5/2=2.5 cm

How a screw changes force?

• In comparison to the large amount of force used to overcome resistance force, the screw only uses a small force to turn.

• A screw can hold something together, keeping the force equal and together.

• Also a screw can lessen the force when something goes around down a screw.

Pencil Sharpener

• Wedge

• Screw

• Wheel and Axle

• Lever

Bicycle

• Screw

• Wheel and axle

• Lever

• pulley

Wing-Handle Corkscrew

• Rack and pinion

• Wheel and axle

• Screw

• Lever

• http://www.coe.uh.edu/archive/science/science_lessons/scienceles1/screw.htm

• http://www.uark.edu/depts/aeedhp/agscience/simpmach.htm

• http://en.wikipedia.org/wiki/Screw• http://www.ehow.com/how-does_4598341_what-

simple-machines-pencil-sharpener.html• http://www.mos.org/sln/Leonardo/

GadgetAnatomy.html

Wheel & Axle

By Delaina Padillas

Explanation

• A simple machine consisting of a large wheel securely attached to a smaller wheel, called an axle. When one turns, the other turns. A full rotation of a wheel equals a full rotation of an axle.

Pictures!!

Mechanical Advantage

• The advantage to using a wheel and axle is the ratio of the radius of the wheel to the radius of the axle.

• The relationship is demonstrated by these equations:

MA = Distance moved by the wheel / distance moved by the axle

MA = Diameter of the Wheel / Diameter of the Axle

Changes Force

• You can apply the input force to the axle rather than to the wheel to increase speed.

Example

• The diameter of a wheel is 10 cm. The radius of the axle is 4 cm. (*Remember radius is half of the diameter)

• MA=Diameter of the Wheel/Diameter of the Axle.• MA=10 cm/8 cm• MA=1.25 cm

Compound Machine #1

• Wheelbarrow

• Uses lever and wheel & axle

Compound Machine #2

• Lighter

• Uses 2 Wheels and a Lever

Compound Machine #3

• Bicycle

• A pulley, wheel & axle, lever, and screws

Annotated Bibliography

• http://www.uark.edu/depts/aeedhp/agscience/simpmach.htm

• http://sceince.jrank.org/pages/4056/Machines-simple-wheel-axle.html

• http://www.sciencebyjones.com/simple_machines.htm

• http://education.jlab.org/jsat/powerpoint/0708_simple_machines_8.ppt#301,22,Wheel and Axel

• http://en.wikipedia.org/wiki/Wheel_and_axle

The Wedge- A Simple Machine

Justine Lundsted

What is a wedge?

A triangular shaped tool One of the six classic simple machines A portable inclined plane Uses:

Separating two objects or parts of an object

Lifting an object Holding an object in place

Mechanical Advantage of a Wedge

The mechanical advantage of a wedge can be found by dividing its length by its width. MA=L/W

The more narrow the angle of the wedge- the greater ratio of its length to its width, which gives it a better mechanical advantage (unless dealing with elastic material).

Example

The wedge you are using to chop wood is 12 inches long and 3 inches wide. What is the mechanical advantage of this wedge?

MA= L/W MA= 12 in. / 3 in. MA= 4 in.

How Does the Wedge Change the Force?

The wedge converts the force applied to its blunt end into forces perpendicular to its length (as seen in the picture to the left).

Compound Machine #1(pencil sharpener)

Contains a screw and wedge

Compound Machine #2 (a bucket)

Works with a wheel and axle, a pulley, and a wedge.

Compound Machine #3(boom mower)

Has a wheel and axle, pulley, and wedge.

Bibliography http://en.wikipedia.org/wiki/

Wedge_(mechanical_device) (used for description)

http://images.google.com/imgres?imgurl=http://fabathome.org/machinesandmechanisms/images/ (used for pictures)

http://z.about.com/d/homeschooling/1/0/8/Z/4/machinewedge.png

http://www.uark.edu/depts/aeedhp/agscience/simpmach.htm (used for mechanical advantage)

http://teacher.scholastic.com/dirtrep/simple/wedge.htm

Simple Machine: Lever

Sarah Peiffer

How Does It Work?

A lever operates with a fulcrum, or pivot point, which multiplies the force applied to an object

A lever can be used to move a heavy force over a short distance by exerting a small force over a long distance

There are 3 different kinds of levers

First Class Lever

A lever in which the fulcrum is located between the input force and the output force.Example: Seesaw

Second Class Lever

The input force is on one end and the fulcrum is on the opposite end with the output force in between.Example: Wheelbarrow

Third Class Lever

The output force is on one end opposite the fulcrum and the input force is in between.Example: Tongs

Mechanical Advantage

Mechanical Advantage is the machine’s affect on the output force

Mechanical Advantage = Load / EffortIf a force of

10 N is applied to a move a 100 N weight the MA is 10

How the Force is Changed

Work = Force x DistanceF1D1=F2D2

A force of 10 N can be applied over a distance of 30 feet to move a 30 N force a distance of 10 feet

Example

A force of 20 N is applied to move a 200 N weight. What is the Mechanical Advantage?

MA= 200 N / 20 NMA= 10

Breakdown: Trebuchet

Type 1 LeverWheel and AxelScrew

Breakdown: Wheelbarrow

Type 2 LeverWheel and AxelScrew

Breakdown: Stapler

Type 3 LeverModified ScrewWedge

Bibliography

http://www.math.nyu.edu/~crorres/Archimedes/Lever/LeverLaw.html This is a site describing the history behind the lever.

http://en.wikipedia.org/wiki/Lever This site defined lever and gave its equation. It also defined

the 3 types if levers. http://www.uark.edu/depts/aeedhp/agscience/simpmac

h.htm This site defines mechanical advantage and explains how it

works. http://www.dynamicscience.com.au/tester/solutions/hy

draulicus/simplemachineslevers4.htm http://library.thinkquest.org/J002079F/lever.htm

The Incline: The Incline: A Simple Machine A Simple Machine

PowerPoint by:PowerPoint by:

Kiersha KellerKiersha Keller

What is an incline?What is an incline?

An incline is a flat surface who’s An incline is a flat surface who’s endpoints are at different heights.endpoints are at different heights.

Rather than moving across the plane Rather than moving across the plane vertically, the force that you need to vertically, the force that you need to give is reduced.give is reduced.

The trade-off is that an object must The trade-off is that an object must go more of a distance. go more of a distance.

The Advantages of The Advantages of Using an InclineUsing an Incline

It reduces the force neccesery to It reduces the force neccesery to move something across an area on a move something across an area on a low angle. low angle.

The trade off is that you must go a The trade off is that you must go a longer distance.longer distance.

However, the amount of work stays However, the amount of work stays the same.the same.

Breaking it down…Breaking it down…

When something is put on an incline, When something is put on an incline, it will only move if the force of it will only move if the force of friction is a smaller amount then the friction is a smaller amount then the combined force of both gravity and combined force of both gravity and normal forces. normal forces.

When the angle of the incline is 90* When the angle of the incline is 90* the object will only free fall. the object will only free fall.

The incline formula is the following:The incline formula is the following: IMA= length/heightIMA= length/height

How the Incline helps…How the Incline helps…

The incline helps by allowing gravity The incline helps by allowing gravity to do some of our work. to do some of our work.

When you tilt a surface in the When you tilt a surface in the downward direction (like an incline), downward direction (like an incline), the gravitational force beats out the the gravitational force beats out the friction. friction.

In this case, the incline helps to take In this case, the incline helps to take away the friction so the surface slides away the friction so the surface slides across more easily.across more easily.

MA= S/H MA= S/H

MA= 18/3= 6

WheelbarrowWheelbarrow

Wheel& Axel

Inclined Plane

Lever

Inclined Plane Wheel &

Axel

EscalatorEscalator

Incline Cable CarIncline Cable Car

Wheel &Axel

Inclined Plane

Pulley

Websites that I usedWebsites that I used

http://en.wikipedia.org/wiki/Inclined_http://en.wikipedia.org/wiki/Inclined_planeplane

http://www.usoe.k12.ut.us/curr/Scienhttp://www.usoe.k12.ut.us/curr/Science/sciber00/8th/machines/sciber/macce/sciber00/8th/machines/sciber/machines.htmhines.htm

http://www.mos.org/sln/Leonardo/Invhttp://www.mos.org/sln/Leonardo/InventorsToolbox.htmlentorsToolbox.html

+2 more!+2 more!

http://www.edheads.org/activities/leshttp://www.edheads.org/activities/lesson_plans/pdf/sm_04.pdfson_plans/pdf/sm_04.pdf

http://library.thinkquest.org/CR02101http://library.thinkquest.org/CR0210120/Compound%20machine.html20/Compound%20machine.html