Pulleys

Fixed Pulley:Fixed Pulley:

•Wheel attached to surface

•Changes the direction of the applied force

•NO mechanical advantage – same amount of force is required

Movable PulleyMovable 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

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

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.

Combined Combined (double) Pulley(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.

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

The more lines of support (ropes) a pulley has, the more mechanical advantage it has!