# Simple Machines - PowerPoint PPT Presentation

Simple Machines

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Simple Machines

## Simple Machines

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##### Presentation Transcript

1. Simple Machines Group BB

2. A Simple Machine: Wedge

3. What is a wedge? • A wedge is an object with at least one slanting side and a sharp edge end. It can also: • Hold an object in place • Separate two objects or portion of an object. • Lift an object.

4. Calculating Mechanical Advantage • A wedge is like an inclined plane, but can be moved. • To calculate the mechanical advantage, divide the wedge length by its width at the thickest edge.

5. Changing the Force • When adding force to the wide end of the wedge, it changes to perpendicular force to the inclined surface.

6. Example • If you have a wedge that has a length of 8 inches and is 3 inches thick, the mechanical advantage of the wedge would be 2.67

7. Compound Machine #1 • Can Opener • The actual part of the can opener that opens the can itself is made up of a wedge. • It is also made up of lever, gear, and wheel and axle.

8. Compound Machine #2 • Stapler • The staples that go through the paper are in fact wedges. • The stapler itself is made up of levers.

9. Compound Machine #3 • Shovel • A Shovel is made up of two simple machines, one being a wedge, the other being a lever.

10. Bibliography • http://www.usoe.k12.ut.us/curr/science/sciber00/8th/machines/sciber/machine3.htm • Gives examples of simple machines that are wedges, also provides an explanation of what a wedge is. • http://www.mikids.com/Smachines.htm • Gives the definition of each of the six simple machines, and shows pictures. • http://science.jrank.org/pages/4060/Machines-Simple.html • This site has an in depth explanation of a wedge. • http://www.edheads.org/activities/simple-machines/ • Helps understand which tools in the shed and house have simple machines, and what simple machines those tools are made up of. • http://en.wikipedia.org/wiki/Wedge_(mechanical_device) • Gives the mechanical advantage of the simple machine.

11. Wheel and Axle By James Pesta

12. Wheel and Axle definition • Wheel and axle is simple machine with a cylinder on a rod that is pulled or turned by something (like a rope) to create a force. more easily

13. Picture of Wheel and axle

14. Ideal Mechanical Advantage To find the mechanical advantage you have to use this formula Example: If your axle radius is 5 inches and your wheel radius is 15 inches your mechanical advantage is 3

15. Force The wheel and axle changes the forces coefficient of friction by rolling instead of sliding. When a object slides it have just one surface contacting the ground and gravity is pushing down, but it an object it rolling gravity has a little less affect on it and the friction is significantly less.

16. Compound Machine #1 Bike-Simple Machines-screw, wheel and axel, lever, pulley

17. Compound Machine #2 Wheel Barrel-Simple Machines-lever wheel and axle

18. Compound Machine #3 Drill-Simple Machines- screw, wheel and axle, lever

19. Sites • Dictionary.com • library.thinkquest.org/CR0210120/Compound%20machine.htm • wikipedia.com • science.jrank.org/pages/4059/Machines-Simple-Compound-machine.htm • edheads.org

20. The Pulley By Steven Tanner Period 1

21. What’s a Pulley? A pulley is a wheel with a grooved rim that turns inside of a frame and serves to change the direction of or to transmit force.

22. Close Up!

23. Why pulleys? Pulleys are mainly used to lift heavy objects. They work by reversing the direction in which force must be applied from an upward direction to a downward one, which allows gravity to work on its user’s side. This way, objects require less force to be lifted to their proper locations.

24. Mechanical advantage is the ratio of a mechanism’s output force to its input force. Pulleys are the only simple machines in which mechanical advantage is limited to whole numbers. In the diagram to the right, the mechanical advantage is one: the force put into pulling one side of the rope or string is equal to the force pushing the other side up. Thus, the effort is equal to the load, and… Pulleys and Mechanical Advantage

25. MA=Load/Effort A simple way to gain the mechanical advantage is to turn the pulley upside down. Notice how there are two lengths of rope meant to pull up a single load. This means that each side of the lifting rope supports half of the load. Therefore, with the equation above, we can find that the mechanical advantage is 1/.5=2 (You could also count how many times the rope goes over a pulley, as seen on the example). Gaining Mechanical Advantage

26. Example • In the example to the right, the rope goes over a pulley five times. Therefore, this pulley system’s mechanical advantage is 5.

27. Crane • A crane is basically a giant system of multiple pulleys. The one shown here is small and uses only two, but some of the largest have been known to use three or ever four! In any case, the pulley will be pulled up by the string in order to lift an object into the air and move it to a new location. Cranes also use inclined planes to raise and lower carried objects to even greater (or lesser) heights.

28. Roller Coaster • Roller coasters use a pulley to pull the train up the first hill. They also use inclined planes to help it reach the finish, wheels and axles for the car’s wheels to move, and screws to hold the trains together.

29. Bowflex • The Bowflex uses many different simple machines, such as pulleys, a lever, screws, inclined planes, and wheels and axles. • Pulleys can be visibly seen to add resistance for workouts, a lever can adjust parts, screws keep the machine together, wheels and axles allow for additional movement, and inclined planes are used in making the seat.

30. Bibliography • http://library.thinkquest.org/C004451F/nfpulley.htm • http://www.made-in-china.com/showroom/zygj1986/product-detailtqbmujSChQIp/China-Crane-Pulley.html • http://www.schoolsliaison.org.uk/astonhall/candles/spits/pulley1.htm • http://etc.usf.edu/clipart/25700/25757/fixed_pulley_25757.htm • http://www.school-for-champions.com/science/machines.htm This website gave me a simple definition of what a pulley was. • http://en.wikipedia.org/wiki/Pulley A great source for specific informaqtion, wikipedia gave me a ton of information that I needed to know throughout my slideshow. • http://www.technologystudent.com/gears1/pulley7.htmThis website was extremely useful for teaching me how to find a pulley’s mechanical advantage. It offered diagrams and drawings in addition to this information.

31. LeverA Simple Machine By: Nicolas Joel Sholly The best

32. Lever (explanation) • A lever is a rigid object that when used with the right pivot point it multiplies the mechanical force to another object.

33. Mechanical Adv. • To find the mechanical advantage you take the length of the arm giving effort divided by the arm giving resistance. • MA= Effort Arm / Resistance Arm

34. Force • The torque on an object about some pivot point is due to the action of a force on the object. The lever trades force for distance by pulling or pushing to a section of the bar.

35. Complex Machines • A stapler is an example of a complex machine. The top arm is a lever and the staple is a wedge.

36. Wheel Barrel • A wheel barrel is a complex machine. It has a lever (handle bars), wheel and axel (wheel), and inclined plane (bucket).

37. Can opener • A can opener has four different simple machines. It has a lever (handles), wedge (blade), gear (turns can), wheel and axel (handle that is turned).

38. Bibliography • Edheads.org • Wikipedia.org • Enchantedlearning.com • Vectorpark.com • Library.thinkquest.org

39. The Screw Terry Mack Jr.

40. Screws-How? Screws can be used to apply force on objects, like vises, clamps and monkey wrenches. A screw could actually be described as an incline plane wrapped around an axis. Effort force is applied to the larger circumference of a screw, like someone turning a wood screw with a screwdriver. The force is transmitted down the spiral to the tip. The tip of the screw moves into the wood, and this is the resistance force.

41. Screws-Examples

42. Mechanical Advantage The ratio of the threads determines the mechanical advantage. The pitch is the distance between the threads. Suppose you have a screw with 12 threads per inch being turned by a screwdriver with a handle with a diameter of 1 inch. The pitch is .083. Then you must find the circumference of the screwdriver handle. So, circumference = 3.14 x diameter = 3.14 x 1 = 3.14 then, mechanical advantage = circumference/pitch mechanical advantage = 3.14/.083 mechanical advantage = 37.83

43. Compound Machine

44. Simple machines Incline

45. Incline • An incline is a flat surface where the endpoints are at different levels. • By moving an object up an inclined plane you need less force than pushing it up a vertical surface, but you have to go a longer distance.

46. Mechanical Advantage • The mechanical advantage of an incline is that the ratio of the length of the sloped surface to the height it spans. • You can find the mechanical advantage by dividing slope over height. ma=s/h

47. Changing of the force • Inclines split the force into two smaller forces, one perpendicular and one parallel to the plane. • Only the parallel force needs to be counteracted.

48. Example • For the picture below, assume that the length of the slope, or s, equals 15 feet. • The height, or h, is 3 feet. • Mechanical advantage=s/h • =15/3 • =5

49. Compound machine #1 • Wheelbarrow • Is made up of wheel & axle, lever and incline

50. Compound Machine #2 • Rollercoaster • Is made up of wheel & axle, pulley, and inclined plane