Pulleys

1
Pulleys
2

• Fixed Pulley
• Wheel attached to surface
• Changes the direction of the applied force
• NO mechanical advantage same amount of force is
  required

3

• 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

4
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
5

• Combined (double) Pulley
• Has at least two wheels
• The more complex the pulley, the more the effort
  needed to move the object decreases

6
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.
7
The more lines of support (ropes) a pulley has,
the more mechanical advantage it has!
http//www.swe.org/iac/LP/pulley_03.html