Ever wonder how those big cranes can lift of the Matson container at the shipyard? Or how cranes can lift of the steel bars and hull them up to the top of a 50 story building? It’s all about simple machines, but a particular simple machine called a pulley. Basically it is just a string wheel that allows a string to pass through as it pulls a load.
Well, the fourth graders were given the task of building a pulley in order to move a load. If their case, a bottle of gravel. Students were also measuring how much force it took to move that load by using a spring scale. There were two types of pulleys they built, tested and compared: fixed pulley and a fixed pulley. Using these two types of pulleys they were to compare how much effort it took to raise the same bottle of gravel.
Which one do you think too the least amount of force to lift?
