1. The problem statement, all variables and given/known data This isn't a math problem but just a vocab question, what is the total energy of a system called? 2. Relevant equations 3. The attempt at a solution In the physics textbook by resnick and halliday, they define mechanical energy of a system as the energy of a certain Configuration and equates it to KE + PE. What I am searching for is mechanical energy plus internal energy of a system (which would include the heat that results from a nonconservative force acting on an object in the system), hence "total energy"