simple machines. wheel and axle pulley lever inclined plane wedge screw
TRANSCRIPT
Work• Work is the transfer of energy from one
system to another
• Mechanical work is the product of the magnitude of force in the direction of displacement and the distance through which a body moves
Displacement
Work
• Work indicates that a force is exerted and is moving something
• Simple machines make work easier
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Wheel and Axle
• Two connected circular objects of different diameters
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Special Wheel and Axle
• Gear– Wheel with teeth– Teeth of one gear
push against teeth of another gear
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Pulley
• A wheel (and axle) with a rope running over it
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Pulley
• A pulley can change the direction of force
• Multiple pulleys in combination can reduce the effort force to move an object
10 lb 10 lb
10 lb
80 lb
10 lb
Lever
• A bar that is free to pivot around a fixed point
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Lever• Three types
– First Class• Fulcrum between effort and resistance forces• Effort and resistance forces in same direction
Effort Resistance
Lever• Three types
– Second Class• Resistance force between fulcrum and effort force• Effort and resistance forces in opposing directions
Resistance
Effort
Lever• Three types
– Third Class• Effort force between fulcrum and resistance force• Effort and resistance forces in opposing directions
Resistance
Effort
Inclined Plane
• Slanted surface used to raise an object
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© iStockphoto
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Wedge
• Inclined plane that moves
• A triangle shape with a sharp point
• Can split, cut, tighten, or hold things together
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Screw
• Inclined plane wrapped around a shaft
• Used to fasten things together or move things
Corkscrew conveyor
Worm gear
Parking garage ramp© iStockphoto
© iStockphoto
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