Lately I am answering a great many questions regarding the implementation of simple machines in the Rube Goldberg Project. There are a great many resources on the Internet to supplement the discussions in class but here are a few things to keep in mind.
There are different ways to think about simple machines but the goal of using a machine is usually to accomplish a task the is useful: lifting a box, separating objects, fastening objectes together. In each case you should consider the work INTO the machine and the work OUT of the machine. It is entirely possible that these two are close to the same quantity (Work In = Work Out) but what is different is the FORCE. For example. the goal of using a ramp is to lift something to a higher location, something that might be too heavy to just lift, then using a ramp makes sense because LESS force is needed but over a larger distance. Since: W = Fd then a smaller force would require a larger distance moved. [LINK] [LINK]
As far as this project is concerned, the machine needs to be implemented such that the output of the machine is necessary to continue the Rube Goldberg device. In other words (for example) if you are using a pulley in your project then the two sides of the pulley are needed for the machine to continue, and the output side of the pulley isn’t just for show.