Fifth meeting (Monday, February 7)

Before we began

4th & Final Design: lever and pulley #2

Constructed Machine

Working on the new design

Working...

     On class on Friday, we learned the two main types of simple machines; the lever and the inclined plane. We learned how different simple machines are variations of the lever and inclined plane, and we got one crucial fact from the lesson; the inclined plane causes the most friction, and lever causes the least friction. This was the reason why our inclined plane-and-pulley design wasn’t working, so we decided to go back to our old design of the lever-and-pulley.
    The only hurdle we faced was that there was no place to put the fulcrum. As we were digging around, looking for materials to use for our flexible fulcrum, we found two long pieces of wood. We thought that if we drilled a hole in each one, criss-crossed the two pieces of wood, and stuck something like a pin the overlapped hole, it could act as a flexible fulcrum. Excitedly, we completely dismantled and redesigned the machine by going back to our old plan, just with a different fulcrum. We quickly set up an inverted block and tackle pulley with the output force going downward and drilled holes for the fulcrum screwdriver to go through. We drilled two more holes on one piece of wood and put mini screwdrivers through them so the input weight and the string attached to the lever could hang off of it. It was perfect; with just little input force, the 600g weight rose over 5 cm.
    The main difference between this machine and the original lever-and-pulley machine was that the fulcrum was in different spots. By putting the fulcrum on the floor, it greatly improved our design.
    We learned the importance of perseverance because this was our fourth design, and we were glad that we hadn’t given up. Next meeting, which is going to be during science class, we plan to measure the exact amount of weight that is required to lift the 600g weight up 5 cm, and we also plan on doing calculations to find the ideal and actual mechanical advantage of our nifty lifting machine.