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Where does the energy come from?
Imagine an iron cube with a weight of 1N on the floor. It has zero gravitational potential energy (GPE). If I lift it 1m up, it will have 1J of GPE, and I will have done at least 1J of work in order to lift the block. However if I use a fixed magnet fixed 1m above the ground (NOT an electromagnet) and the block is lifted up 1m the block gains 1J of energy, but the magnet has not done any work. Where does the energy come from as it can neither be created nor destroyed as we all know.
2 Answers
- 1 decade agoFavorite Answer
Why wouldn't the magnet have done any work. It must be exerting a force on the cube in order to lift it. Since work = force x distance, and there is a force and distance traveled, then work is done.
- Lola FLv 71 decade ago
What do you mean, "The magnet has not done any work?" Of course it did. It lifted the cube. The energy to do that work was originally stored as electromagnetic potential energy in the EM field.