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Pulleys

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					Pulleys
Fixed Pulley:
•Wheel attached to
surface
•Changes the direction of
the applied force
•NO mechanical
advantage – same amount
of force is required
Movable Pulley:
• Pulley moves along the
  rope
• Wheel supports the load
• Effort is in the same
  direction as movement
• Reduces the forces needed
  to move an object
     In the second picture, the weight is held by two ropes instead
       of one. That means the weight is split equally between the
           two ropes, so each one holds only half the weight.



http://www.swe.org/iac/LP/pulley_03.html
Combined
(double) Pulley:
•Has at least two wheels
•The more complex the
pulley, the more the effort
needed to move the
object decreases
    Pulleys are used to gain
 mechanical advantage trading
the amount of rope you have to
  pull to lift an object for how
   heavy the object can be.
       The more lines of support (ropes) a pulley has, the more mechanical
                               advantage it has!




http://www.swe.org/iac/LP/pulley_03.html

				
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