1. Simple Machines Mechanical Advantage WORK 1 Efficiency Effort Force
Sound
Efficiency
Effort
Mechanical Advantage
WORK
Force

2. 2
Goals
What do I need to know?
1.Analyze the simple machines qualitatively and quantitatively in terms of force, distance, work and mechanical advantage
2. Explain the different types of simple machines.
3. Be able to calculate amount of work done by a simple machine
4.Be able to calculate mechanical advantage
5. Use mathematics & computational thinking to identify the relationships between work, mechanical advantage, and 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= Force x distance
W = f x d

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

5. What is a machine? -a machine that does work with only one movement.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. How Machines Work You do WORK on the machine
And
The machine does WORK on an object
Your WORK=Fxd
The machine’s WORK=Fxd
The amount of work is EQUAL!

7. A machine can make work easier in two ways:
Machines only make work easier…HOW? 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

8. 7.1
Mechanical Advantage
CLIP
…is the number of times the machine multiplies the effort force (your force)

9. Ideal vs Actual Mechanical Advantage
7.1
Ideal vs Actual Mechanical Advantage
IMA
AMA
IMA-WHAT ACTUALLY happened!!
Why is this different from IMA?
FRICTION….
Converts some energy in into thermal energy, so less USEFUL energy out.

10. 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.

11. Get a calculator
Work on Vocab (p.10)

12. Working Together (you and the machine)

13. 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.
NEVER OVER 100%

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

15. 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?

16. Levers Fulcrum 12 (Fe) Effort Force LOAD (Fr) Resistance Force
The force the person applies to the machine
Place where a lever pivots
The distance the machine moves the load
Fulcrum
(Fe) Effort Force
(dr) Resistance Distance
Effort Arm
Resistance Arm
LOAD
(de) Effort Distance
(Fr) Resistance Force
The distance the person moves the machine
The force the machine applies to the load

17. Based on the position of the fulcrum13
Levers
There are types of Levers
Based on the position of the fulcrum

18. 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.

19. Levers 15 Wheelbarrow Nutcrackers
2nd Class: The resistance force is between the effort force and the fulcrum.
Wheelbarrow
Nutcrackers
The handle of a pair of nail clippers

20. 16
3rd Class: the effort force is between the resistance force and the fulcrum.
Levers
Garden Hoe
Your arm
Catapult
Fishing rod
Tongs (double lever) (where hinged at one end)

21. Mechanical Advantage of Levers17
Mechanical Advantage of Levers
3 Ways
5/5=1
10/5=2
10 cm
5 cm
5 cm
LOAD
Effort arm
Resistance arm
As the length of the effort arm increases, the MA of the lever increases.

22. Mechanical Advantage of Levers
You can also use the Mechanical Advantage Formulas:
IMA
Ideal MA
AMA
Actual MA
“Give me a place to stand and with a lever I will move the whole world.” -Archimedes

23. MA of Levers Problems
Example #1: To pull apart two pieces of wood, you apply a force of 50 N to a lever. The lever then applies a force of 640 N to the wood. What is the mechanical advantage of the lever?

24. MA of Levers Problems
Example #2: A lever and fulcrum are used to raise a heavy rock, which has a weight of 350 N. If the lever has a mechanical advantage of 9, what must the input force on the lever be in order to just begin lifting the rock?

25. Example #3: A construction worker uses a board and log as a lever to lift a heavy rock. If the input arm is 6 meters long and the output arm is 1.2 meters long, what is the mechanical advantage of the lever?

26. From study packet…page 2
1) A construction worker uses a board and log as a lever to lift a heavy rock. If the input arm is 3 meters long and the output arm is 0.75 meters long, what is the mechanical advantage of the lever?

27. From study packet…page 2
2) Marshall wants to remove a tree stump from the ground. To do this, he puts one end of a long beam under the stump and puts all of his weight on the other end. His weight is just enough to lift the stump. The stump weighs 400 N. Marshall weighs 250 N. What is the mechanical advantage of the lever Marshall is using?

28. From study packet…page 2
3) A lever and fulcrum are used to raise a heavy rock, which has a weight of 445 N. If the lever has a mechanical advantage of 9.50, what must the input force on the lever be in order to just begin lifting the rock?

29. From study packet…page 3
4) Susan and Jake take Susan’s car for a drive and get stuck in the mud. The back of Susan’s car weighs 900 N. They applied 700 N of force to the tree branch lever. What is the mechanical advantage of the tree branch?

30. From study packet…page 3
5) Three of your friends are all sitting on one end of a seesaw. The combined weight is 275 N. The length from the fulcrum to your friends is 2.5 m. The rest of the seesaw (from the fulcrum to you) is 4.5 m.
What is the MA?
B) What effort force is needed to lift your friends?

31. From study packet…page 3
6) How can you increase the mechanical advantage of a lever?

32. 18
REVIEW
Position of Fulcrum

33. 19
Pulleys

34. 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

35. 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

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

37. Mechanical Advantage of Pulleys23
MA =2
Effort Force
Test question: Resistance force is equal to the ___________ of the __________.
100N
Resistance Force

38. Mechanical Advantage of Pulleys24
MA =2
Effort Force
100N
Resistance Force

39. Mechanical Advantage of Pulleys25
MA =4
Effort Force
100N
Resistance Force

40. Example problem 1: A simple pulley system uses a 40N effort force to move a 80N load. What is the Mechanical Advantage of the pulley?

41. Example Problem 2: To lift a load 5cm with a pulley system, 15cm of string had to be pulled. What is the mechanical advantage?

42. A pulley is used to raise a heavy crate
A pulley is used to raise a heavy crate. The pulley is such that an input force of 223 N is needed to provide an output force of 1784 N. What is the mechanical advantage of this pulley?

43. A complex arrangement of pulleys forms what is called the block in a block and tackle. The rope used to lift the pulleys and the load is the tackle. A block and tackle is used to lift a truck engine, which has a weight of nearly 7406 N. The force required to lift this weight using the block and tackle is N. What is the mechanical advantage of the block and tackle?

44. A block and tackle with a mechanical advantage of 48 is used to lift a piano 11 m to the third floor of a building. Although the arrangement of pulleys in the block and tackle makes it easy to lift the piano, it takes a long time because of the length of rope that must be pulled to lift the piano a small amount. What is this length, or input distance, of the rope that must be pulled?

45. Marc is asked to raise a flag at the Remembrance Day ceremonies at his school. If the effort force to raise the flag is 50 N and the load force the flag plus the rope is 50 N what is the mechanical advantage of the pulley on the flagpole?

46. 26

47. 28.a
Inclined Planes

48. 28.b
Inclined Plane
A sloping surface that reduces the amount of force required to raise and object.
Resistance Distance (h)
Effort Distance (L)

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

50. Mechanical Advantage of Inclined Planes30

51. Animation Starter on page 6 in packet…click

55. Questions: Since doing a task with or without a machine requires the same amount of work, why use machines?
Answer: They give you a mechanical advantage.
You get your force multiplied.

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

57. The effort force is applied to the larger wheel
31.b
Ideal Mechanical Advantage = Radius of wheel
    Of wheel and axle        Radius of axle
The effort force is applied to the larger wheel
Gears are wheels with teeth.

58. 31.c
One day you made a mousetrap cars The car has the following measurements for their wheels:  the radius axle (the small wheel) measured only 1 cm.  The radius of the larger wheel (the one that touched the pavement) measured a whopping 10cm.  What was the mechanical advantage of these wheels?
Ideal Mechanical Advantage = Radius of wheel
    Of wheel and axel        Radius of axel
IMA = 10
This means with each turn of the axle, you get 10 times the distance.  Those big wheels really help!

59. Why do you think you see these type of door knobs in handicap accessible areas?

60. 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: Bolts, Spiral Staircase, Parking Deck

61. 33
The closer together the threads are, the longer the inclined plane is relative to the length of the screw or bolt, so the greater its mechanical advantage.
Therefore, if the threads are closer together, you need to apply less force to penetrate the wood or other object.

62. 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

63. Review Clip 35

64. Quick Review Look at your “19cm lever” on pg 7.
How much work did you do?
How much work did the lever do?
If you used a lever with an effort arm 20cm and a resistance arm of 10cm to lift a box with a weight of 700N, what would be the mechanical advantage of the lever?
If you used the pulley in the picture to lift a box with a weight of 500N, about how much force would you need to apply to the pulley?

65. 36
Rube Goldburg
Keep You From Forgetting To Mail Your Wife's Letter

66. 37
Simplified Pencil Sharpener
CLIP

67. EOCT
QUESTIONS 38

68. 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

69. 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

70. 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

71. TedEd: The mighty mathematics of the lever
What does he say at 1:20 that is wrong?

72. Simple Machines: Pulleys (12:52)

73. 27

74. Simple Machines