Pardon my simple question, but I'd like some general intuition on what I'm reading in the thermochemistry section of my chemistry text book (I'm posting the question here because it seems more related to physics, but if it needs to be moved, that's OK). All right, I'm reading that: Total energy = kinetic energy + potential energy + internal energy. That's great, I get that, and I get the relationship between kinetic energy and potential energy, and I understand that internal energy is the energy of the particles. But I don't see the relationship of internal to either kinetic or potential; does there have to be a relationship? Can internal energy be transformed into kinetic or potential energy of the whole system, or are they completely separate? I can't imagine a case where it can, but maybe someone here can explain it better. In other words, if an object/substance has zero kinetic energy, and zero potential energy, and some amount of internal energy, can that internal energy be transformed into kinetic or potential energy of that object/substance? Or can kinetic and potential energy only be added to that same object through energy transfer from an outside source (my body/hand expending energy to lift it up, then dropping it, for example)? My intuition wants to say this is correct, but maybe there's some case I'm not considering where this isn't necessarily the case. Now, about the Joules question. What does it mean to have 1 kg[itex]\bullet[/itex]m2/s2? In plain English, what does it mean? The energy required to move one kilogram one meter squared (what?) per second squared (huh?). If my question needs clarification, let me know and I'll do my best to reword it. Thanks in advance. Please don't be too harsh! Haven't taken any physics, and we haven't had lecture on this material yet.