I like the idea and the (to abuse a word) *energy* of the presenter, but I canâ€™t bring myself to like the way the question was answered.

energy = the ability to do work

work = the act of displacing something using force

force = any interaction that changes the motion of a mass

mass = a form of energy

conclusion: energy = everything

energy, work, force, massâ€¦ this all reminds me of Feynmanâ€™s wakalix.

Iâ€™m looking for a better answer. One that I can give my daughter, who would not like this one because she likes things more clearly cut. I taught her division, using pizzas and bags of pennies and apples, when she just wasnâ€™t *getting* the math teacherâ€™s jargon laden symbolic methods. She got it almost instantly - because sheâ€™s brilliant - and the only hard part was *un*teaching the mistaken impressions she had from trying to understand the schoolteacher.

I always liked using Zelaznyâ€™s phrase *â€śthe force that through the circuit drives the currentâ€ť* to describe energy, but it turns out thatâ€™s actually voltage. (I think I just topped out my unintelligibly geeky joke quota for the week.)

Maybe energy is mass in a format thatâ€™s been divorced from the direct influence of gravity? Hmmâ€¦ maybe not. Still looking.

Agreed, itâ€™s unsatisfying, but Iâ€™m not entirely conceived you can do much better.

Itâ€™s like non-Euclidean geometry. For millennia we talked about points, lines, and planes without realizing that these are undefined terms. Or rather, that any â€śdefinitionâ€ť consists only of the effects of the relations the axioms define among them. Change those relations, and the definitions change. Euclidâ€™s fifth postulate (the parallel lines one) was considered ugly for millennia, but if turned out if you change it everything still makes sense, except all of a sudden you are describing â€ślinesâ€ť which are the shortest paths on (positively or negatively) curved surfaces; the plane is no longer flat.

At root, what energy *is,* is a mathematical property (an operator) in the laws of physics. To paraphrase another Feynmann quote, itâ€™s the thing that determines how fast (temporally) the phase of a quantum wavefunction changes. Itâ€™s also the thing that bends spacetime in relativity (more fundamental than mass, yes). It doesnâ€™t have a definition, and if it did, it would be defined in terms of other undefined terms. But it *does* have meaning, in terms of the relationships and rules it obeys.

Not very helpful without calculus and algebra, but fairly accurate. As with wakalixes, youâ€™re better off sticking to concrete examples for a while.

Watt is energy/time.

I thought Watt was on second?

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