Hi, i want to intiate the discussion on energy?Although its a very basic and general topic, i request u all to participate to study it thoroughly...... how do u define energy? According to common definition given by all, it is the ability to do work. But work is also a form of energy. So i dont think that is the correct way of defining energy. And in one book, i read heat and work are energy in transit and remaining all are stored energy(Ref:thermal engineering by mathur and mehta). In other book, i read all the forms of energy can be grouped into two categories:stored(potential) energy and kinetic(energy in motion)........No Definition is clear.... So What is the definition of energy? "That definition should perfectly define all forms of energy, say potential, kinetic, heat, thermal,work, internal,nuclear, chemical". What is the link between energy, properties of a system? Why should really the energy flows from one body to another? need ur valuable points!