1. Simple Machines 1
Effort
Efficiency
Mechanical Advantage
WORK
Force

2. Goals Be able to calculate mechanical advantage2
Goals
Analyze the simple machines qualitatively and quantitatively in terms of force, distance, work and mechanical advantage
Be able to calculate mechanical advantage
Be able to calculate amount of work done by a simple machine
Explain the different types of simple machines.

3. Work FLASH BACK Transfer of Energy from one place to another.3
Work
FLASH BACK
Transfer of Energy from one place to another.
Applying a force over a certain distance.
Calculating Work:
Work (J)= Force x distance
W = f x d
Power= work/time

4. 6 types of simple machines4
6 types of simple machines
clip

5. What is a machine? A device that makes work easier.5
A device that makes work easier.
What is a simple machine?
-a machine that does work with only one movement.
You still do the same amt of work —it’s just easier!

6. A machine can make work easier in two ways:6
A machine can make work easier in two ways:
Multiply the force you apply.
A Car Jack
Change the direction of the force.
Blinds

7. 7
Mechanical Advantage
CLIP
Number of times the machine multiplies the effort force (The force you apply to it)

8. Watch for this in all Simple machines:8
Watch for this in all Simple machines:
Machines are a “give and take relationship.” If you get your force multiplied, then you must go a greater distance.

9. Efficiency of a Machine9
A measure (%) of how much work put into a machine is actually changed to useful work put out by the machine.
90 J .
100 J
NEVER OVER 100%

10. According To “The Law of Conservation of Energy” Can this exist?10
Ideal machine
Efficiency =100%
MA= 100%
According To “The Law of Conservation of Energy” Can this exist?
Does not exist.
FRICTION

11. Types of Machines Levers11
Types of Machines Levers
A lever is a bar that is free to pivot, or turn about a fixed point.
How can we use levers?

12. Levers 12 Fulcrum Resistance Distance Effort Distance LOAD Effort Arm
Resistance Arm
Resistance Force
Effort Force

13. Levers There are three types of Levers13
Levers
There are three types of Levers
Based on the position of the fulcrum

14. The fulcrum is between the resistance force and the effort force.14
Levers
1st Class: Crowbars, pliers, scissors, seesaw
The fulcrum is between the resistance force and the effort force.
The closer the fulcrum to the resistance force, the more the lever multiplies the force.

15. Levers 15 Wheelbarrow Nutcrackers Crowbar (forcing two objects apart)
2nd Class: The resistance force is between the effort force and the fulcrum.
Wheelbarrow
Nutcrackers
Crowbar (forcing two objects apart)
The handle of a pair of nail clippers

16. 16
3rd Class: the effort force is between the resistance force and the fulcrum.
Levers
Hoe
Your arm
Catapult
Fishing rod
Tongs (double lever) (where hinged at one end)

17. Mechanical Advantage of Levers17
5/5=1
10/5=2
20/5=4
Effort arm
Resistance arm
As the length of the effort arm increases, the MA of the lever increases.

18. 18
REVIEW
Position of Fulcrum

19. 19
Pulleys

20. Pulleys Multiply the effort force change the direction of the force 20
What is a pulley?
A pulley is a grooved wheel with a rope or chain running along the groove.
What can a pulley be used for?
Multiply the effort force
change the direction of the force

21. Pulleys 21 Two types of Pulleys: Fixed pulley Movable pulley
A pulley that is attached to something
Only changes the direction of the force
Movable pulley
The pulley is free to move
***Block and Tackle***
Combination of both types of pulleys

22. Mechanical Advantage of Pulleys22
Only changes the direction of the force
MA =1
10 N
resistance Force
Effort Force
10 N

23. Mechanical Advantage of Pulleys23
MA =2

24. Mechanical Advantage of Pulleys24
MA =2

25. Mechanical Advantage of Pulleys25
MA =4

26. 26

27. 27

28. 28
Inclined Plane
Resistance Distance (h)
Effort Distance (l)

29. Mechanical Advantage of Inclined Planes29
Effort Distance (l)
Resistance Distance (h)

30. Mechanical Advantage of Inclined Planes30

31. 31
Wheel and Axle
Consisting of two wheels of different sizes that rotate together
The effort force is applied to the larger wheel

32. Ideal Mechanical Advantage = Radius of wheel
    Of wheel and axel         Radius of axel
Gears are wheels with teeth.

33. Screw An inclined plane wrapped around a cylinder32
Screw
An inclined plane wrapped around a cylinder
The inclined plane lets the screw slide into the wood.
Examples: Bolt, Spiral Staircase

34. 33

35. Wedge 34 An inclined plane with one or two sloping sides.
Changes the direction of the effort force.
Examples: Axe, Zipper, Knife
Effort Force
Resistance force

36. Review Clip 35

37. 36
Rube Goldburg

38. 37
CLIP

39. EOCT
QUESTIONS 38

40. A lever is used to lift a box. The mechanical advantage of the lever is39
It took only 200 N of force to lift a 1000N object, therefore the machine multiplied the force 5 times!
A 25 B 10 C 5 D 4 OR
50 cm
10 cm

41. 40
What is the amount of useful work output of a 25% efficient bicycle if the amount of work input is 88 N-m?
A 2200 N-m
B 113 N-m
C 63 N-m
D 22 N-m
Wout
.25 =
88 J

42. Which of the following is an example of41
Which of the following is an example of
a compound machine?
A bicycle
B crowbar
C doorknob
D ramp

43. Simple Machines