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Simple Machine: wheel and axle, pulley and screw

Simple Machine: wheel and axle, pulley and screw. Group FF. Wheel and Axel. Josephine Harper. What is a Wheel and Axel?. A wheel and axle is a lever that rotates in a circle around a center point or fulcrum. (1). How does it work?.

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Simple Machine: wheel and axle, pulley and screw

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  1. Simple Machine: wheel and axle, pulley and screw Group FF

  2. Wheel and Axel Josephine Harper

  3. What is a Wheel and Axel? • A wheel and axle is a lever that rotates in a circle around a center point or fulcrum.(1)

  4. How does it work? • The radius of the wheel is larger than the axle so the force is spread to the axle, which has a smaller radius. The initial force is smaller then the resulting force.(2) R/r

  5. How does it change the force? • Work = Force × Distance • Since the wheel is always larger than the axle, effort applied to the wheel will always move further than the load at the axle.(3)

  6. Mechanical advantage MA=R/r • Suppose the Radius of the wheel is 9ft and the axle has radius of 3ft. 9ft/3ft = 3ft

  7. Compound Machine #1 • Wheel and Axle • Lever

  8. Compound Machine #2 • Screws • Wheel and Axle • Lever • Pulley

  9. Compound Machine #3 • Lever • Screws • Wheel and axle • Wedge

  10. More wheel and axles

  11. bibliography • (1) http://www.usoe.k12.ut.us/curr/science/sciber00/8th/machines/sciber/machine7.htm (explains the wheel and axle) • (2) http://www.worsleyschool.net/science/files/wheel/andaxle.html (work of a wheel and axle) • http://www.fi.edu/pieces/knox/automaton/wheel.htm (give examples of wheel and axles and a description) • http://www.mikids.com/SMachinesWheels.htm (explains the wheel and axle) • (3) http://encarta.msn.com/encyclopedia_761562392/wheel_and_axle.html (a description of the wheel and axle and its benefits)

  12. Pulley By: Donald Heist IV

  13. Definition of a Pulley • It’s a wheel with a lip that allows you to transmit power from the ground to a higher place such as a roof or a tree it also allows for a change in direction by the means of a belt, cord, rope, or chain.

  14. Variables: P = Load (number of pennies) P(actual) = Actual Load P(calc) = Calculated Load N = Number of Ropes (Mechanical Advantage) P = Pa x N F = Friction F = P(actual) - P(calc.) Ideal mechanical advantage

  15. How a pulley changes the forceand an example of mechanical advantages • Change in direction • To have less force you must pull on the rope or chain a longer distance. • The number of vertical rope’s except for the one your pulling on is your mechanical advantage. • So if there is 5 vertical ropes including the one you are pulling on then your mechanical advantage would be 4.

  16. A single rope pulley

  17. A 5 chain pulley

  18. A 7 belt driven pulley

  19. Bibliography • http://teacher.scholastic.com/dirtrep/Simple/pulley.htm • http://www.uark.edu/depts/aeedhp/agscience/simpmach.htm • http://www.school-for-champions.com/science/machines.htm

  20. Screw: “A Simple Machine” Justin Riegel

  21. What Is It? • A screw is one of six simple machines. It usually turns rotational force into linear force, but can also do the opposite. It is mainly used to hold stuff together. It is a modified version of an inclined plane.

  22. Mechanical Advantage • An advantage of a screw is that the more threads the more advantage. Another plus is if threads are closer together which also goes along with more threads. Mechanical advantage is the circumference divided by the pitch. Pitch is the number of threads in 1 inch of the screw.

  23. How Force Is Affected • A screw changes force, because the longer the screw the more you will have to turn it to make it tight.

  24. Compound #1: Bicycle • One example of a compound machine is a bicycle. The wheels and pedals are wheel and axles. The brake handles are levers, and the seat adjustment is a screw.

  25. Compound #2: Scissors • Scissors are also a compound machine. It has levers as handles. Which then are squeezed to close the blades that are wedges. But a screw completes it by holding the two pieces together.

  26. Compound #3: Locking Pliers • On a pair of locking pliers the handles act as levers. The adjusting bolt acts as a screw to adjust the diameter size of the pliers.

  27. Bibliography • http://en.wikipedia.org/wiki/Screw Found basic information and the definition of a screw • http://inventors.about.com/od/sstartinventions/a/screwdrivebr.htm Found about different types of screw and history of screws • http://www.northerntool.com/webapp/wcs/stores/servlet/category_6970_94+1483+771365 • http://science.jrank.org/pages/4058/Machines-Simple-Screws.html • http://www.uark.edu/depts/aeedhp/agscience/simpmach.htm Found how and the equation for finding the mechanical advantage of a screw

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