Simple machines

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Created by
Carmen Armstrong

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  • Simple machine
    A device that requires a single force to work; made of only one or two parts
  • Types of simple machines
    • Incline plane
    • Wedge
    • Lever
    • Wheel and axle
    • Pulley
  • Lever
    Made up of the input force (effort force applied), the output force (force the lever applies to the load), and the load force (force the input force has to overcome)
  • Classes of levers
    • Class 1 (fulcrum between load force and input force)
    • Class 2 (load force between fulcrum and input force)
    • Class 3 (input force between fulcrum and load force)
  • Class 1 lever

    • Fulcrum is between the load force and the input force
  • Class 1 levers examples
    • Scissors
    • Teeter-totters
    • Crowbars
  • Class 2 lever
    • Load force is between the fulcrum and input force
  • Class 2 lever example
    • Wheelbarrow
  • Class 3 lever
    • Input force is between the fulcrum and the load force
  • Class 3 lever example
    • Your arm
  • You want to remember which part is in the middle for each class of lever
  • Pulley systems are commonly found in elevators, cranes, and construction equipment.
  • Mechanical Advantage

    The advantage a machine gives us. It is a number that tells us how many times "easier" it is to do a job with a machine compared to not having the machine.
  • Ways to calculate Mechanical Advantage
    1. If using a lever: MA = Length of Effort Arm divided by Length of the Load Arm
    2. If using a lever, pulley or moving something else: MA = Input Distance divided by the Output Distance
    3. If you know the force needed to operate the machine and the force needed to lift the load: MA = Output Force divided the Input Force
  • Levers

    • Rigid arms that pivot about a fulcrum
    • Designed to redirect force and help us to lift things
  • Effort

    The force applied on a lever
  • Load

    The item being lifted, the weight of the object being moved
  • To lift a load, the upward force must be greater than the weight (force of gravity) acting on the object
  • Three classes of levers

    • Based on where the fulcrum, effort and load are
  • System

    A group of parts that work together to do something
  • Systems explained
    • They are designed to accomplish a specific task
    • They can have many or just a few components
  • Types of systems

    • Human-made
    • Natural
  • Types of systems

    • Physical
    • Social
  • Inputs

    All of the things that go into the system to make it work (forces, energy, materials)
  • Outputs

    The task the system is designed to complete
  • Side effects

    Things that happen because of the system, but weren't intended
  • Sub-systems

    Smaller working systems within the bigger system
  • Example of a system

    • Transportation system (roads, sidewalks, airports, train tracks, gas stations, mechanics, parking lots, drivers)
  • Ideally, systems are designed to optimize human and natural resources
  • Our job is to constantly think about systems and consider how we can improve them to get the same output with fewer inputs or fewer side effects
  • Simple machines

    Tools we can use to make work easier
  • Types of simple machines

    • Inclined plane
    • Wedge
    • Screw
    • Lever
    • Wheel and axle
    • Pulley
  • Lever

    A rigid bar that pivots at a point called the fulcrum
  • Inclined plane

    A tilted plane that makes a job easier
  • Knives and stairs are just inclined planes
  • A screw is an inclined plane wrapped around a pole so it doesn't take up as much room