Question

You read about a rope and pulley machine that was able to produce equal amounts of output work and inputinput. Was this a realistic example? Why or why not?

Answer 1

It probably isn't a realistic example. Most of the time, some of the work you put in can be lost. It could be due to friction if something is making contact with a surface, or air drag if its in the air, etc. In your example, pulleys have friction between itself and the rope or cables. Some of the energy/work that we put into it will be lost due to friction.

Answer 2

an ideal single pulley would require as much work in as it would put out - i.e. there is no mechanical advantage on a single pulley. That being said, as @CShrix mentioned, the real world is plagued with inefficiencies ranging from the mass of the pulley and the rope, to the friction in the system. Though you're question may be more complicated than that, depending on what your "inputinput" is