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Mechanical Systems Unit

Mechanical Systems Unit. Simple Machines. What is a machine?. Machine – a device that helps us perform a task. Machines can:. Change energy from one form to another Ex. Car Engine Chemical energy in Kinetic energy out. Machines can:. Transfer forces Example: Car transmission

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Mechanical Systems Unit

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  1. Mechanical SystemsUnit

  2. Simple Machines

  3. What is a machine? • Machine – a device that helps us perform a task

  4. Machines can: • Change energy from one form to another Ex. Car Engine Chemical energy in Kinetic energy out

  5. Machines can: • Transfer forces Example: Car transmission Transmits force from the engine to the axle/wheels

  6. Machines can: • Change the direction of force Example: Raising a flag Pull down on the string, flag goes up

  7. Machines can: • Change the magnitude of forces Example: Gears in a Bike Allows you to apply less force over a greater distance to climb a hill

  8. Machines can: • Change distance and speed Example: Bike transmission Allows you to apply a smaller force over a greater distance or a greater force over a smaller distance

  9. Two Types of Machines • Lever Type • Lever, pulley, wheel and axle, gears • Incline Plane Type • Incline plan, wedge, screw

  10. The Lever Family

  11. Fundamental Concept • We can reduce the amount of force we need to apply by pulling over a greater distance • We can increase the amount of force we apply by pulling over a smaller distance

  12. Definitions Lever – a rigid bar that can rotate freely about a pivot point (or fulcrum) Fulcrum – A pivot point that the lever can rotate about

  13. What does a lever do? Levers turns your effort into a force on a load Effort Force Load Force

  14. Where are the load and effort forces?

  15. Classes Of Levers 1st Class Lever • Fulcrum is in the middle, load and effort to either side

  16. Classes Of Levers 2nd Class Lever • Load is in the middle, fulcrum and effort to either side

  17. Classes Of Levers 3rd Class Lever • Effort is in the middle, fulcrum and load to either side

  18. Remember 1 2 3 F L E

  19. Terminology • Effort force (FE) – a force applied to a lever (N) • Load force (FL) – a force exerted on a load (N) or a force used to do something

  20. Terminology • Effort distance (dE) – the distance from the fulcrum to the effort (m) • Load distance (dL) – the distance between the load and the fulcrum (m)

  21. Lever Powered Bike

  22. Identify the Type of Lever

  23. Levers that don’t look like levers… • Don’t think a lever is always an unbendable bar • It can be something that acts like an unbendable bar! • Take a look

  24. Pulleys

  25. Wheel and Axle

  26. Gears

  27. Biology’s Levers

  28. Pulleys Pulley Systems – Machines that move objects with less force Pulley – A wheel that rotates around a fulcrum in it’s centre

  29. Examples

  30. Pulley Systems • Pulley systems allow you to pull with less force over a greater distance • The advantage provided by the pulley is based on the number of support strands on the mass

  31. For example, the following pulley would require you to pull with half the force over twice the distance

  32. Pull with ¼ the force over 4 times the distance

  33. Wheel and Axle • A large circular disc (wheel) with a small rigid rod (axle) through the centre • Oldest wheel and axle is around 5000 years old

  34. The Wheel and Axle

  35. Gears • Toothed wheels of different diameters

  36. Worm Gear

  37. The Inclined Plane

  38. Inclined Plane • Increases the load that can be moved with a given force • Makes the force less because the inclined plane supports some of the weight of an object (easier than lifting vertically)

  39. Examples of an Inclined Plane • Ramp • Stairs – it’s easier to climb stairs than a ladder • Easier to push a piano up a ramp than to lift it onto a truck

  40. Wedge • A double inclined plane (axe, door stop) • Increases applied force and changes it’s direction • Transforms a lateral force into a splitting force

  41. Screw • A twisted inclined plane (road around a mountain) • Changes turning force into vertical force

  42. Compound Machine • Made of two or more simple machines

  43. Work • Pg 76 # 6,7 • Pg 77 # 1,5,6

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