Q: What really is energy?
My general chemistry teacher was really taken aback when I raised my hand to ask him for a definition of energy. He genuinely didn't know what to say, at the end of class he came to try to clarify what I was asking for, if I meant a specific type of energy, and he ended the conversation saying that he prefers not to venture into the topic and that I should ask a physics teacher. Which I don't have. I don't know if it was a silly question to ask, it's just been ages since I did any science and I like to try to understand everything and it felt like a gap in my knowledge.
So anyways, how do you define energy? What do all the forms of energy have in common?