Physical Science - Chapter 13 

Work and Machines

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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

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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

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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

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13D Inclined Plane

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

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

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