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Physical Science - Chapter 13 

Work and Machines

13A Work and Mechanical Advantage

  • Work and Power
    • %%Work%%: the energy transferred to a system by an external force when it acts on the system to move it
    • %%Power%%: the rate of doing work
  • Machines
    • %%Simple Machines%%: a basic mechanical device that changes the magnitude, direction, or distance traveled of the force used when doing work
    • %%Inclined Plane%%: simple machine that consists of a plane whose opposite ends are at different heights
    • %%Mechanical Advantage%%: the amount by which a simple machine multiplies an input force to produce an output force
  • Mechanical Advantage and Efficiency
    • %%Ideal Mechanical Advantage%%: the mechanical advantage for an ideal machine (100% efficient) with no friction
    • %%Actual Mechanical Advantage%%: the mechanical advantage that accounts for all mechanical losses sustained through using a machine
    • %%Efficiency%%: a comparison of the amount of usable energy remaining after a process with the original amount of energy that went into the process

13B Lever

  • Simple Machine: Lever
    • %%Lever%%: a simple machine that consists of a rigid bar that turns about a pivot point (the fulcrum)
    • %%Fulcrum%%: the point about which a lever pivots or rotates
  • How Levers Work
    • %%Torque%%: a force that tends to cause a rotation about a pivot point
  • Classifying Levers
    • %%First-Class Lever%%: a lever in which the fulcrum is between the input and output forces
    • %%Second-Class Lever%%: a lever in which the output force is between the input force and the fulcrum
    • %%Third-Class Lever%%: a lever in which the input force is between the output force and the fulcrum

13C Wheel and Axle

  • Simple Machine: Wheel and Axle
    • %%Wheel and Axle%%: a simple machine consisting of a wheel with a rod running through its axis that acts as the pivot point
  • %%Gear%%: a simple machine that consists of a wheel with teeth on its perimeter that mesh with similar teeth of other gears to do work
  • %%Pulley%%: a simple machine that consists of a wheel and axle system with a groove around the perimeter of the wheel in which a rope, cable, or belt moves with the wheel as it rotates
  • Pulley Systems
    • Single pulleys
    • Block and tackle

13D Inclined Plane

  • Simple Machine: Inclined Plane

    • %%Inclined Plane%%: a simple machine that consists of a plane whose opposite ends are at different heights

  • %%Compound Machine%%: a machine that combines two or more simple machines