1000 joules of energy are put into a pulley syastem, and 400 joules come out. what does the law of conservation of energy imply about the lost energy?

The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed from one form to another. Therefore, based on this law, the lost energy in the pulley system implies that it has been transferred or transformed into another form. In this case, it is likely that the lost energy has been transformed into other types of energy, such as heat or sound, which are not useful for the intended purpose.