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

Types of Pulleys FIXED PULLEY MOVABLE PULLEY COMBINED PULLEY Flat Pulley

Mechanical Advantage The 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 ropes 7 – 1 (the one you are pulling) = 6 therefore 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 / Effort If 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 Distance F1D1=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 N MA= 10

Breakdown: Trebuchet Type 1 Lever Wheel and Axel Screw

Breakdown: Wheelbarrow Type 2 Lever Wheel and Axel Screw

Breakdown: Stapler Type 3 Lever Modified Screw Wedge

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/simpmach.htm This site defines mechanical advantage and explains how it works. http://www.dynamicscience.com.au/tester/solutions/hydraulicus/simplemachineslevers4.htm http://library.thinkquest.org/J002079F/lever.htm

The Incline: A Simple Machine PowerPoint by: Kiersha Keller

What is an incline? An incline is a flat surface who’s endpoints are at different heights. Rather than moving across the plane vertically, the force that you need to give is reduced. The trade-off is that an object must go more of a distance.

Simple Inclines

The Advantages of Using an Incline It reduces the force neccesery to move something across an area on a low angle. The trade off is that you must go a longer distance. However, the amount of work stays the same.

Breaking it down… When something is put on an incline, it will only move if the force of friction is a smaller amount then the combined force of both gravity and normal forces. When the angle of the incline is 90* the object will only free fall. The incline formula is the following: IMA= length/height

How the Incline helps… The incline helps by allowing gravity to do some of our work. When you tilt a surface in the downward direction (like an incline), the gravitational force beats out the friction. In this case, the incline helps to take away the friction so the surface slides across more easily.

MA= S/H MA= 18/3= 6

Wheelbarrow Wheel & Axel Lever Inclined Plane

Escalator Inclined Plane Wheel & Axel

Incline Cable Car Wheel & Axel Inclined Plane Pulley

Websites that I used http://en.wikipedia.org/wiki/Inclined_plane http://www.usoe.k12.ut.us/curr/Science/sciber00/8th/machines/sciber/machines.htm http://www.mos.org/sln/Leonardo/InventorsToolbox.html

+2 more! http://www.edheads.org/activities/lesson_plans/pdf/sm_04.pdf http://library.thinkquest.org/CR0210120/Compound%20machine.html