Introduction to levers.

1. Simple Machines Part 1
by Mrs. Burch 9/8/17

2. A simple machine is a mechanical
device that makes work easier for
us by allowing us to push or pull
something over a longer distance.

3. There are 5 basic types of simple
machines.

4. The 1st
type of simple machine
is...

5. The Lever

6. Introduction to Levers
https://youtu.be/YlYEi0PgG1g

8. Watch this video of a truck
being lifted with a lever.
https://youtu.be/fX3doG_z9l4

9. Introducing (drum roll, please)
…the Lever!

10. A lever includes a stiff structure such as a wood
board that pivots on a fixed point called the fulcrum.

11. A seesaw (a.k.a. teeter totter)
is a lever.

12. Every Lever has 3 parts:
1. Resistance (a.k.a. Load)
2. Effort Force (a.k.a. Input Force)
3. Fulcrum

13. Okay, but what ARE these 3
parts?!?!

14. Well, let’s look at the 1st
part...Resistance (a.k.a. Load).

15. The resistance (load) is what
you are trying to lift or move.

16. Why do you think the object you
are trying to move is called the
“resistance”?

17. Well...the heavier the object, the
more it “resists” being moved.

18. What is the resistance or load in
this picture?

19. What is the resistance or load in
this picture?

20. What is the resistance or load in
this picture?

21. What is the resistance or load in
this picture?

22. Now, let’s look at the 2nd
part of a
lever...Effort Force (a.k.a. Input
Force).

23. The Effort Force (a.k.a. Input
Force) is the effort or work you
have to put in, so the object will
move.
Which letter shows the effort force?

24. In this use of the lever, what is the
effort force (input force)? What is
the resistance (load)?
See answer
on next slide.

25. This man must push down on the
board to cause the tire to lift. So,
the effort force is the man pushing
down...

26. ...and the resistance, or load, is the
tire.

27. Lastly, let’s look at the 3rd
part of
a lever...the Fulcrum.

28. The Fulcrum is a fixed pivot
point.

29. “Fixed” means the fulcrum
doesn’t move.

30. Where is the fulcrum?

31. Where is the fulcrum?

32. Where is the fulcrum?

33. Where is the fulcrum?

34. Where is the fulcrum?

35. Where is the fulcrum?

36. Let’s review the parts of a lever:

37. 1. The work you have to put in
to make the object move is
called...

38. 1. The work you have to put in
to make the object move is
called...effort force or input
force.

39. 2. The object that you want to
lift or move is called...

40. 2. The object that you want to
lift or move is called...the
resistance or load.

41. 3. The fixed point on which the
lever pivots is called...

42. 3. The fixed point on which the
lever pivots is called...the
fulcrum.

43. 4. The load is...

44. 4. The load is...the object you
are trying to lift or move.

45. 5. The other word for “load”
is...

46. 5. The other word for “load”
is...“resistance”.

47. 6. Effort force is...

48. 6. Effort force is...the work you
put into moving the object.

49. 7. Another term for effort force
is...

50. 7. Another term for “effort force”
is...“input force”.

51. 8. The fulcrum is...

52. 8. The fulcrum is...the fixed
point on which the lever
pivots.

53. Good job!

54. The order of the load, effort, and
fulcrum determines the lever’s
class. There are 3 classes of
levers.

55. A 1st
class lever has the
fulcrum somewhere between
the effort force and the load.

56. Go outside to demonstrate 2
levers in action.

57. The load moves in the opposite
direction of the effort force.

58. So, if you push down on one
end of a lever, the load at the
opposite end will move ___ and
vice versa.

59. If you push down on one end of
a lever, the load at the opposite
end will move _up_ and vice
versa.

60. 1st
Class Lever
Question #1: What do you think will happen
if the fulcrum is closer to the load than to the
effort?
Effort
Load
Fulcrum

61. 1st
Class Lever
Answer #1:
There is a gain in force, but there is a loss
in speed and distance.
Effort
Load
Fulcrum

62. 1st
Class Lever
What does that mean?
Effort
Load
Fulcrum

63. Notice that the load doesn’t go as high
when the fulcrum is closer to the load.
Therefore, there is a loss in distance.

64. But, if the fulcrum is close to the load, it
will be a lot easier to move. Therefore,
there is a gain in force.
More effort needed
Less effort needed

65. 1st
Class Lever
Question #2: What do you think would
happen if the fulcrum is closer to the effort
than the load?
Effort
Load

66. 1st
Class Lever
Answer #2:
There is a loss in force, but there is a gain
in speed and distance.
Effort
Load

67. The load moved higher when the fulcrum
is closer to the effort. Therefore, there is
a gain in distance.

68. But, it is much harder to make the load go
up when the fulcrum is closer to the effort.
Therefore, there is a loss in force.
Needs a lot more effort
Needs less effort

69. What are some examples of 1st
class levers?

70. A seesaw is a 1st
class lever.
Where is the fulcrum? Effort force? Load?

71. Pliers are a 1st
class lever.

72. Knowing that to make the effort easier, the
fulcrum needs to be closer to the load than the
effort, how could a tool manufacturer make it
even easier for you to use the pliers?

73. Answer: A tool manufacturer could make the
handles longer to make it even easier for you.

74. This is why you want to use
pruners with really long handles
to cut thick branches.

75. A door handle is a 1st
class
lever.
Where is the force? The load? The fulcrum?

76. Where is the force? The load? The fulcrum?
Force
Fulcrum
Load

77. A bicycle brake lever is a 1st
class lever.

78. Where is the load?

79. The load is where the brake pads
squeeze the tire.

80. A dolly (hand truck) is a 1st
class
lever.

81. Which is the force? The load?
The fulcrum?

82. Which is the force? The load?
The fulcrum?
Force
Load
Fulcrum

83. A power switch is a 1st
class
lever.

84. A railroad track switch.
fulcrum
fulcrum
load
load
effort
effort

85. A hammer pulling a nail is also a 1st
class lever.
Where is the
fulcrum?
The effort
force?
The load?

86. A hammer pulling a nail is also a 1st
class lever.
Where is the
fulcrum?
The effort
force?
The load?
Load
Effort Force
Fulcrum

87. A pry bar is similar to a hammer
and is another 1st
class lever.

88. Scissors are two 1st
class levers put
together.
loadload

89. Okay, now we know what a 1st
class lever is like. What about a
2nd
class lever? What is it like?

90. A 2nd
class lever puts the load
somewhere between the effort
force and the fulcrum.

91. The fulcrum is at one of the
ends of the lever and is usually
closer to the load.

92. What are some examples of 2nd
class levers?

93. The wheelbarrow is the most
famous 2nd
class lever.

94. The foot is a 2nd
class lever.

95. A stapler is a 2nd class lever.

96. A bottle opener is a 2nd class
lever.

97. Which arrow points to the load?
The effort? The fulcrum?

98. Which arrow points to the load?
The effort? The fulcrum?
fulcrum
load
effort

99. A nutcracker uses two 2nd
class
levers put together.

100. Nail clippers use two 2nd
class
levers.

101. A paper cutter is a 2nd
class
lever.

102. Where is the resistance? The
effort? The fulcrum?

103. Where is the resistance? The
effort? The fulcrum?
effort
resistance
fulcrum

104. Okay, now we know what 1st
AND 2nd class levers are like.
What about the last one...the
3rd class lever? What is it like?
nother

105. First, take what you know about
what is located in the middle of 1st
and 2nd
class levers to determine
what must be in the middle of 3rd
class levers.
Review: What is in the middle?
1st
class levers:
2nd
class levers:

106. First, take what you know about
what is located in the middle of 1st
and 2nd
class levers to determine
what must be in the middle of 3rd
class levers.
Review: What is in the middle?
1st
class levers: The fulcrum
2nd
class levers: The load

107. So, did you figure it out? What
is in the middle of a 3rd
class
lever?

108. If you answered effort force,
you’re right!
Yay!Yay!

109. So, a 3rd
class lever has the
effort force between the load and
the fulcrum.

110. What are some examples of 3rd
class levers?

111. A fishing rod is a 3rd
class lever.

112. A hammer is a 3rd
class lever.

113. A baseball bat is a 3rd
class
lever.

114. Your arm is a 3rd
class lever.
Load
FulcrumFulcrum
F
o
r
c
e
F
o
r
c
e

115. Chopsticks are two 3rd
class
levers used together.

116. Tweezers are a 3rd
class lever.
Where is the force? The load? The fulcrum?

117. Where is the force? The load? The fulcrum?
Fulcrum
Force
Load

118. Test your knowledge of levers:

119. Where is the effort, fulcrum, and
load? What class?

120. Force
Load
Fulcrum
A shovel is a 1st
class lever.

121. Boat oars: Where is the
fulcrum, force, and load? What
class?

122. Boat oars are 1st
class levers.

123. Tongs: Where is the fulcrum,
force, and load? What class?

124. Tongs use two 3rd
class levers
together.
effort forceeffort force
fulcrumfulcrum
loadload

125. Where is the effort, fulcrum, and
load? What class?

126. A broom is a 3rd
class lever.
fulcrumfulcrum
effort forceeffort force
loadload

127. Bottle opener: Where is the
fulcrum, force, and load? What
class?

128. A bottle opener is a 2nd
class
lever.

129. Wheelbarrow: Where is the
fulcrum, force, and load? What
class?

130. A wheelbarrow is a 2nd
class
lever.

131. Are you ready for the test?

132. Okay, then let’s review before
the test:

133. What is the mechanical
advantage of levers?

134. What is the mechanical
advantage of levers?
They make it easier to do work.

135. How do levers make work
easier?

136. How do levers make work
easier?
They make it easier because
the work is spread out over a
longer distance...

137. ...so you are spreading the work
out over a longer period of time.

138. You still have to do the same
amount of work, but it’s easier
because you don’t have to do it
all at once.

142. The man on the left weighs more than the
woman on the right. Would could they do to
make the lever balance horizontally?

143. What is the technical term for
the object you want to move?

144. Answer: Load or Resistance

145. What is the term for the pushing
or pulling you have to do to
make the lever work?

146. Answer: Effort Force or Input
Force

147. https://youtu.be/E5pZ7uR6v8c
Video of man using levers to move heavy stone blocks and more.