Simple Machines: Pulley Lab

      In our most recent lab, we spent time working with various pulley systems to help understand the relationship between force and distance.

      During the first few days of the lab, we constructed a simple pulley machine using only one pulley, a brass weight or 200g, and a length of string. We basically just did a few tests to see how much force was required to move the weight 10cm with and without a pulley.

  Our results ending up showing us that it required roughly 1N to move the weight 10cm with a pulley, and roughly 2N to move the weight 10cm without a pulley. We can conclude from these short tests that with one simply pulley, we only have to use half of our force to move an object that would normally take twice the force. This concept is very practical in the real world. Today workers everywhere use pulleys to get their job done with less effort.

      After completing the work with out simple pulley systems, we moved on to more complex pulley systems with more strings. A very useful tool we used in this lab was the force probe. This device allowed us to measure the amount of force being used to pull the brass weight with various pulley systems. 

 

(We connected these force probes to our labquest devices and were able to read how much force was being used to lift our 200g mass.)

      We used a simple pulley, one with two strings, and one with four strings. As we completed our tests we found out that less force was required with more stings/pulleys. For example, with a simple pulley, the required force was almost 2N. But with a four string pulley, the required force was 0.5N. From our work it was clear to us that the more complex pulley system we had, the less amount of force was required.

(This whiteboard shows our work in graph/data table form. After graphing all of our work we were able to see that each test took up the same area on the graph.)

After completing this lab, I was able to see how these simple pulley systems play vital roles in the real world. Workers today, especially at docks and construction sites, use pulley systems to lift heavy weights and get their jobs done easier. 

 

(This is an example of a simple pulley system used on boats to lift heavy cargo onto their decks)

(This crane also has lots of pulley systems which allow it to lift items normally to heavy for the amount of force it uses)