Simple Machines Part 2

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Simple MachinesPart 2

• Lever
• Wheel and Axle
• Pulley

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Simple Machines
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Lever

• What is it?
• A bar that is free to pivot (rotate or turn)
  around a fixed point (fulcrum)
• What is it used for?
• To move a resistance or load
• What is the purpose of a lever?
• To pry, lift, transport, or open something

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Lever

• In order for a lever to be classified as a lever,
  it must have
• A fulcrum
• A resistance arm
• An effort arm

Effort
Lever
Resistance
Fulcrum
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Lever

• There are three kinds or classes of levers
• First Class
• Second Class
• Third Class

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Lever

• First Class Lever
• Has the fulcrum in between the resistance arm and
  effort arm
• Examples?
• See-Saw

Effort
Resistance
Fulcrum
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Lever

• Second Class Lever
• Has the resistance arm in between the fulcrum and
  the effort arm
• Examples?
• Wheelbarrow

Effort
Resistance
Fulcrum
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Lever

• Third Class Lever
• The effort arm is between the resistance arm and
  fulcrum.
• Examples?
• Fishing Pole

Effort
Resistance
Fulcrum
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Lever

• Identify the following as First, Second, or Third
  Class Levers
• A rake
• Third Class
• A nutcracker
• Second Class
• A hammer driving in a nail
• Third Class
• A hammer pulling out a nail
• First Class

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Lever

• Mechanical Advantage
• When a machine makes work easier because it
  multiplies the effort being applied, we say the
  machine is providing a mechanical advantage
• Calculation
• Measure the length of the effort arm and the
  length of the resistance arm
• Then, divide the effort arm length by the
  resistance arm length (MA Earm/Rarm)

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Wheel and Axle

• Related to the lever
• It is like a lever that has been wound up
• What is it?
• Two wheels of different sizes that rotate together

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Wheel and Axle

• Parts
• Larger wheel is called the wheel (Effort Arm)
• Smaller wheel is called the axle (Resistance Arm)
• Fulcrum can be found as it travels around

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Wheel and Axle

• Purpose
• Primarily used to make transportation easier
• The larger the wheel compared to the axle, the
  easier it is to use the wheel and axle
• A car steering wheel vs. a bus steering wheel
• Can you think of some examples?

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Pulley

• What is it?
• A grooved wheel with a rope, chain, or string
  traveling around it
• Has a wheel and axle built into it
• Two types
• Fixed
• Moveable

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Pulley

• Fixed
• The pulley is attached to something
• Only changes the direction of your force
• Is a modified First Class Lever the axle is the
  fulcrum and the ropes on either side are the
  resistance and effort arms
• The ideal mechanical advantage of a fixed pulley
  is always 1

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Pulley

• Fixed

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Pulley

• Moveable
• The pulley moves with the object being lifted
• Because of the way the rope is used, it takes
  only half the effort to lift the load

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Pulley

• Moveable

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Pulley

• Block and Tackle
• A combination of pulleys (fixed and moveable)
  used together

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Simple Machines

• Compound Machine
• Any machine made up of two or more simple machines

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Video Quiz Answers

• Lets go over the answers to the video quiz
  questions

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Simple Machines

• Lever
• Wheel and Axle
• Pulley