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  • 1. Work and Simple Machines
  • 2. Simple Machines
    • The six simple machines are:
      • Lever
      • Wheel and Axle
      • Pulley
      • Inclined Plane
      • Wedge
      • Screw
  • 3. Simple Machines
    • A machine is a device that helps make work easier by
      • transferring a force from one place to another
      • changing the direction of a force increasing the size of a force
      • increasing the distance or speed of a force.
  • 4. Mechanical Advantage
    • input force (the force you apply) and the output force (force which is applied to the task).
    • When a machine takes a small input force and increases the magnitude of the output force, a mechanical advantage has been produced.
  • 5. The Lever
    • A lever is a rigid bar that rotates around a fixed point called the fulcrum.
  • 6. The 3 Classes of Levers
    • determined by:
    • location of the effort
    • force and the load
    • compared to the
    • fulcrum.
  • 7. The workman uses a trolley to move the large packing case. The fulcrum is the wheel. First Class Lever
    • In a first-class lever the fulcrum is located at some point between the effort and resistance forces.
      • Common examples of first-class levers include crowbars, scissors, pliers, tin snips and seesaws.
  • 8. Second Class Lever The gardener uses a wheel barrow to lift tools and garden waste. The load is in the centre of the barrow With a second-class lever, the load is located between the fulcrum and the effort force. Common examples of second-class levers include nut crackers, wheel barrows, doors, and bottle openers.
  • 9. Third Class Lever The fisherman catches the fish which becomes the load at the end of the lever.
    • With a third-class lever, the effort force is applied between the fulcrum and the resistance force.
      • Examples of third-class levers include tweezers, hammers, and shovels.
  • 10. Wheel and Axle
    • consist of a large wheel connected to a shaft called an axle.
    • When either the wheel or axle turns, the other part also turns.
  • 11. Pulley
    • A pulley consists of a grooved wheel that turns freely in a frame called a block.
    • A fixed pulley does not rise or fall with the load being moved.
    • A moveable pulley rises and falls with the load that is being moved.
  • 12. Inclined Plane
    • An inclined plane is ramp The inclined plane makes it easier to move a weight from a lower to higher elevation.
  • 13. Wedge
    • The wedge is a modification of the inclined plane. Wedges are used as either separating or holding devices.
  • 14. Screw
    • Think of the threads of the screw as a type of circular ramp (or inclined plane).
  • 15. What’s work?
    • A scientist delivers a speech to an audience of his peers.
    • A body builder lifts 350 pounds above his head.
    • A mother carries her baby from room to room.
    • A father pushes a baby in a carriage.
    • A woman carries a 20 kg grocery bag to her car?
  • 16. What is work?
    • In science, the word work has a different meaning than you may be familiar with.
    • The scientific definition of work is: using a force to move an object a distance
  • 17. Work or Not?
    • According to the scientific definition, what is work and what is not?
      • a teacher lecturing to a class
      • a mouse pushing a piece of cheese with its nose across the floor
  • 18. What’s work?
    • A scientist delivers a speech to an audience of his peers.
    • A body builder lifts 350 pounds above his head.
    • A mother carries her baby from room to room.
    • A father pushes a baby in a carriage.
    • A woman carries a 20 kg grocery bag to her car?
  • 19. What’s work?
    • A scientist delivers a speech to an audience of his peers. No
    • A body builder lifts 350 pounds above his head. Yes
    • A mother carries her baby from room to room. No
    • A father pushes a baby in a carriage. Yes
    • A woman carries a 20 km grocery bag to her car? No
  • 20. Formula for work
    • Work = Force x Distance
    • The unit of work is a joule
  • 21. W=FD
    • Work = Force x Distance
    • Calculate: If a man pushes a concrete block 10 meters with a force of 20 N, how much work has he done?
  • 22. W=FD
    • Work = Force x Distance
    • Calculate: If a man pushes a concrete block 10 meters with a force of 20 N, how much work has he done? 200 joules
    • (W = 20N x 10m)
  • 23. Power
    • Power is the rate at which work is done.
    • Power = Work * /Time
    • * (force x distance)
    • The unit of power is the watt.