1. By Jonathan Lemmon and Brook Dreher

2. Definition of Pulley  a wheel with a grooved rim for carrying a line, that turns in a frame or block and serves to change the direction of or to transmit force, as when one end of the line is pulled to raise a weight at the other end

3. How does it work?  A pulley is also called a sheave or a drum and is a mechanism made up of a wheel on an axle or shaft that may have a groove between two flanges around its boundary.  A rope, cable, belt, or chain usually runs over the wheel and inside the groove, if present.  Pulleys are used to change the direction of an applied force, or realize a mechanical advantage in either a linear or rotational system of motion

4. It looks like this

5. Uses  The pulley is used to move heavy objects by splitting the weight being pulled. Like a crane, it lifts up objects easily by using hydraulics in the arm so it is able to pull objects

6. How do you calculate IMA for the pulley  Efficiency=AMA/IMA x 100%  AMA=F r /F e

7. Other info on pulleys  The pulley you turn causes the other pulley to turn also, because they are connected by a belt. The driver and the follower turn in the same direction.

8. Reference  http://www.eng.iastate.edu/twt/Courses/Und ergrad/packet/info/pulleys.htm http://www.eng.iastate.edu/twt/Courses/Und ergrad/packet/info/pulleys.htm  The book  http://en.wikipedia.org/wiki/Pulley