SIMPLE MACHINES

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SIMPLE MACHINES
SIMPLE MACHINES
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Slide 1
SIMPLE MACHINES

• The Six Simple Machines are
• 1. Lever
• 2. Wheel and Axle
• 3. Inclined Plane
• 4. Wedge
• 5. Pulley
• 6. Screw

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Slide 2
What is a Simple Machine?

• A simple machine has few or no moving parts.
• Simple machines make work easier

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Slide 3
Science Terms to Know

• Force is Push or Pull
• Work Force x distance
• W Fd
• Unit of Work is the Joule or J
• Power Work divided by Time
• P W/t
• Unit of Power is a Watt or W

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Slide 4
Wheels and Axles

• The wheel and axle are a simple machine
• The axle is a rod that goes through the wheel
  which allows the wheel to turn
• Gears are a form of wheels and axles
• Wheels on your bike are wheels and axle

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Slide 5
Pulleys

• Pulleys are wheels and axles with a groove around
  the outside
• A pulley needs a rope, chain or belt around the
  groove to make it do work
• Flagpole uses a pulley to raise the Flag

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Slide 6
Inclined Planes

• An inclined plane is a flat surface that is
  higher on one end
• Inclined planes make the work of moving things
  easier
• Ramp is a type of inclined plane

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Slide 7
Inclined Plane

• Less force is needed to move an object from one
  height to another using an inclined plane than is
  needed to lift the object.
• As the inclined plane becomes longer, the force
  needed to move the object becomes smaller.

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Slide 8
Using Inclined Planes

• Imagine having to lift a box weighing 1,500 N to
• the back of a truck that is 1 m off the
  ground.
• You would have to exert a force of 1,500 N, the
  weight of the box, over a distance of 1 m, which
  equals 1,500 J of work.
• Remember W Fd
  
• Work 1,500N x 1meter 1,500J

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Slide 9
Using Inclined Planes

• Now suppose that instead you use a 5-m long ramp.
  
• The amount of work you need to do does not
  change.
• You still need to do 1,500 J of work. However,
  the distance over which you exert your force
  becomes 5 m.

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Slide 10
So how much Force are you using?

• If you do 1,500 J of work by exerting a force
  over 5 m, the force you push with is only 300 N
  instead of 1,500N if you pushed on flat ground
• The Equation to use is
• 
  

(J)
(m)
F 1,500 5 300N
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Slide 11
Wedges

• Two inclined planes joined back to back.
• Wedges are used to split things.

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Slide 12
Wedges in Your Body

• Your front teeth are wedge shaped
• The teeth of meat eaters, or carnivores, are more
  wedge shaped than the teeth of plant eaters, or
  herbivores

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Slide 13
Screws

• A screw is an inclined plane wrapped around a
  shaft or cylinder.
• The inclined plane allows the screw to move
  itself when rotated.

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Slide 14
Lever

• A lever is any rigid rod or plank that pivots,
  or rotates, about a point.
• The point about which the lever pivots is called
  a fulcrum.
• Input Force is the force being applied by
  YOU.
• Output Force- is the force that the MACHINE
  does

Fulcrum
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Slide 15
What are Input and Output forces of Lever?

• Input force the distance from the Fulcrum to
• F-effort (YOU)
• Output force the distance from the Fulcrum to
  
• F- load (OBJECT)

Input force
Output force
F effort/YOU
F-load/Object
Fulcrum
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Lever

• Are you confused yet?
• Remember this to help you
• Input force is the same as F- effort
• Who is the input force or the F-effort?
• 2. Output force is the same as F- load Simple
  Machine
• What is the simple machine in this example?

The Golfer
The Golf club
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Slide 16
Levers- First Class

• In a first class lever the fulcrum is in the
  middle and the F- load and F-effort are on either
  side
• Think of a see-saw
• or Scissors

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Slide 17
Levers- Second - Class

• In a second class lever the fulcrum is on one
  end, with the
• F-load in the middle and
• F-effort is on other end
• Think of a
• wheelbarrow

F- load
F-effort
Fulcrum
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Slide 18
Levers- Third - Class

• In a third class lever the fulcrum is again at
  the end, but the F- effort is in the middle and
  F-load
• is on the other end
• Think of a pair of tweezers

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Slide 19
Mechanical Advantage or MA of a Lever

• What is it?
• It is how much larger is the Output Force
  compared to Input force
• The higher the MA, the less force you need to
  use to get the job done
• The amount of Work you do doesnt change, ONLY
  the amount of Force you need to use to get the
  job done

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Slide 20
How to calculate the MA of Lever?

• Using the distance from Fulcrum to Input and
  Output Force
• Mechanical Advantage Input force (cm)
• of lever Output force
  (cm)

MA 1/5
MA 5
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Slide 21
How else can you calculate the MA ?

• Use the following MA Equation
• Mechanical advantage Output force or Fout
• Input force or
  Fin
• MA Fout
• Fin
• Calculate this problem
• To open a can of soup you apply a force of
  50N on the can opener. The can opener applies a
  force of 750N on the can of soup. What is the
  Mechanical Advantage of the can opener?

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Answer

• MA Fout 750N 15
• Fin 50N
• 750 divided by 50 15
• The MA of the can opener is 15
• The higher the MA, the less
• work you need to do!!!!!!

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Slide 22
What is the Efficiency of a Machine?

• Efficiency is comparing the amount of work you
  do compared to the amount of work the machine
  does
• When a machine is efficient, you dont have to do
  as much work

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What is the Efficiency Equation?
Slide 23

• Efficiency is measured in
• Efficiency Work out X 100
• Work in
• eff Wout x 100
• Win
• Problem
• You do 100J of work pulling a nail out with a
  hammer. If the hammer does 70J of work, what is
  the hammers efficiency?

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Answer

• eff Wout 70J 70
• Win 100J
• Divide 70 by 100 .70 x 100 70
• Therefore, the hammer is 70 efficient

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Slide 24
Simple Machines

• Simple Machines can be put together in different
  ways to make complex machines

The Ultimate Machine
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Slide 25 Review Questions

• Question Number 1
• Name this Simple machine

Inclined Plane
Or Wheel and Axle
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Slide 26 Question Number 2

• Which type of lever is this?

1. First Class
2. Second Class
3. Third - Class

Third-class lever
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Slide 27 Question Number 3

• All 3 pictures are an example
• of which Simple machine?

Lever
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Slide 28 Question Number 4

• Which simple machines
• do you see in this picture?

Inclined Plane
Wheel and Axle
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Slide 29 Question Number 5

• A can opener is an example of
• First - Class Lever?
• True or False

Effort
True In the First-class lever the Fulcrum is in
middle
Fulcrum
Load
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Slide 26
Slide 30

• Fill-in-the-Blank
• 6. Force is ______ or _______
• 7. Work ______ x _________
• 8. W ____
• 9. Unit of _______is the Joule or J
• Power ______divided by
• 11. P _____
• 12. Unit of Power is a___________

push
pull
force
distance
Fd
work
time
work
W/t
Watt or W
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Slide 31 Questions

• 13. What is the Mechanical Advantage or MA?
• 14. Write the MA equation

It is how much larger is the Output Force
compared to Input force

• Mechanical Advantage Output force or Fout
  
• Input force
  or Fin
• MA Fout
• Fin

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Slide 32 Questions

• 15. Explain what is efficiency?
• 16. What is the efficiency equation?
• BONUS QUESTION
• What is the ultimate Machine?
• SIMPLE MACHINES VIRTUAL QUIZ TAKE THE QUIZ

Efficiency is comparing the amount of work you do
compared to the amount of work the machine does
Efficiency Workout X 100 ____
Workin eff Wout X 100
Win
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