This week in class we did a lab in which we used a program that Dr. Shatz had set up in labview. We used this program to record what happened when we lifted objects into the air. This data was then used to calculate the acceleration and power that was associated with each test. For the first four tests a constant percent of power was used and the weight of the objects was changed for each test. During the second four tests the weight used remained the same while the percentage of power used changed. For all of the tests a single pulley system was used.
The idea behind pulley systems is that a change in direction of the force makes the object easier to lift. In single pulley systems this ease is in being able to pull down on the object instead of having to pull up while in double pulley systems a three to one mechanical advantage is produced which means that the force being exerted on the object is three times that of what is being used to apply tension on the line. In a pulley system the force is referred to as tension and it is uniform throughout the line. In order for an object to be lifted the tension in the line must be greater than the weight of the object being lifted.
Unfortunately do to technological errors the data that was generated from this experiment was lost. Though it can be said that as the mass of an object increased the acceleration decreased, and as power increased with a constant weight the acceleration increased.
Reference
http://www.the-office.com/summerlift/pulleybasics.htm