1. The problem statement, all variables and given/known data Does net force on a system depend on forces that are internal to that system. 2. Relevant equations My problem with understanding this is I don't know any equations that relate net force, external force and/or internal force. 3. The attempt at a solution My guess is that internal work doesn't have to do with the net work of the system but without an equation I can't know sure. So I am not aking for the answer, I would just like an equaion to analyze because I can't find one.