Wheel

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Wheel Axle

• Create a list of everyday objects that contain a
  wheel.

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Wheel Axle

• A simple machine consisting of two circular
  objects of different sizes.
• The axle is the smaller of the two circular
  objects.
• The wheel is where you put the input force into.

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Examples

• Doorknob
• Wrenches
• Ferris wheels
• Screwdrivers
• Steering wheels
• Sink handles

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Anatomy of a Wheel Axle
Wheel
Axle
Axle
Wheel
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SIMPLE MACHINES

• WHEEL AND AXLE
• The wheel and axle is another simple machine. 
  The axle is a rod that goes through the wheel. 
  This lets the wheel turn.  It is easy to move
  things from place to place with wheels and
  axles. 

Wheel
Axle
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The wrench and screw driver are examples of a
wheel and axle, where the screw or bolt is the
axle and the handle is the wheel. The tool makes
the job easier by changing the amount of the
force you exert.
Wheel
Axle
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Why do we need wheels?

• Wheels help us move heavy objects.
• They roll easily.
• Did you know a doorknob is really two wheels
  connected by an axle? You cant see the axle
  because its inside the wheels, but its there!
• If there wasnt an axle, the doorknob wouldnt
  turn!

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Mechanical Advantage

• Divide the radius of the wheel by the radius of
  the axle.

Radius of Axle
Radius of Wheel
Radius of Wheel
MA
Radius of Axle
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Another kind of wheel is called a gear!

• A gear is a wheel with teeth.
• The teeth fit in between each other and turn.
• When one gear turns, its teeth push against the
  teeth of the other gear and they both turn.
• There are gears on your bike, on a can opener and
  on an egg beater.

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Gears
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Gears on a Bike
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Gears on a Can Opener
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Gears on an Egg Beater
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Pulleys

• A simple machine consisting of a grooved wheel
  that holds a rope or cable.
• A load is attached to one end of the rope, and an
  input force is applied to the other end.

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Fixed Pulley

• Changes the direction of the input force.
• The distance through which the input force and
  output force travel are the same.

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Movable Pulley

• The pulley moves with the load.
• Force is multiplied because the combined input
  force is exerted over twice the distance of the
  output force.
• Does not change the direction of the input force.
  

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Block Tackle

• Formed when you combine a fixed pulley and a
  movable pulley together to lift an object.

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Mechanical Advantage

• To calculate the mechanical advantage of a
  pulley, count up the number of supporting
  strands.
• The more supporting strands a pulley system has,
  the greater the mechanical advantage.

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Supporting Strands

• Count the number of string or rope segments.
• If the effort force moves in the same direction
  that the load travels, then you add it to the
  number of rope segments.

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The input force moves in the opposite direction
of the load. So it does not count as a
supporting strand.
Supporting Strand
Therefore this fixed pulley has a MA of one.
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Supporting Strand
The input force moves in the same direction as
the load do we count it as a supporting strand.
Therefore this pulley system has a MA of two.
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The input force moves in the opposite direction
of the load. So it does not count as a
supporting strand.
Supporting Strands
Therefore this block and tackel has a MA of four.

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Pulleys

• Pulleys let you move loads up, down, or
  sideways. 
• Pulleys are good for moving objects to hard to
  reach places. 
• It also makes the effort of moving heavy loads a
  lot less.  

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EXAMPLES OF PULLEYS

• Flag Poles
• Clothes Lines
• Sailboat
• Crane

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Lab Time

• Now its time to put some of this knowledge to
  practice. Working with your groups, you will go
  from station to station and experiment with
  various pulley systems. How fun!!!!