1. Mechanical Systems Unit

2. Simple Machines

3. Machine – a device that helps us perform a task
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. Lever Type Incline Plane Type Two Types of Machines
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. Fulcrum is in the middle, load and effort to either side
Classes Of Levers
1st Class Lever
Fulcrum is in the middle, load and effort to either side

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

17. Effort is in the middle, fulcrum and load to either side
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

26. 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

27. Pulleys

28. Wheel and Axle

29. Gears

30. Biology’s Levers

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

32. Examples

33. 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

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

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

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

38. The Wheel and Axle

40. Gears
Toothed wheels of different diameters

41. Worm Gear

42. The Inclined Plane

43. 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)

45. 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

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

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

48. Made of two or more simple machines
Compound Machine
Made of two or more simple machines

49. Work
Pg 76 # 6,7
Pg 77 # 1,5,6