Where does the potential energy go?? hello.. One of my friend asked me this question, and i had no answer to it. moreover the professors response to it seemed unsatisfactory. The question is: Suppose we have a dipole in a uniform External Electric field, which causes it to rotate (or undergo simple harmonic motion). The energy used to bring about the rotation is stored as the potential energy of the system. Let the dipole moment be θ aligned with the electric field. So there is a some amount of energy used to hold it in that position, and as soon as it is released it tends to align itself in the direction of the electric field. What if we remove the Electric field when the dipole was still making θ angle with earlier existing Electric field. Now in absence of an electric field the dipole should not rotate, then where is the energy gone which was stored in it earlier?? This same thing can be taken with respect to gravity. Suppose we have a body at a height h from the surface of earth then "mgh" amount of energy is stored in the body. If the energy holding it is removed it it falls towards the earth. Now suppose we put the gravity off (lets assume we can). Now the body will not fall... So where does the potential energy stored in the body go?? As an answer to this my professor only said that we can't compare two such systems in presence and absence of gravity or electric field. I have been thinking about this all the while, and the only thing that came to my mind is that we have described the idea of potential energy as the amount of work done against a force acting on the body, when the effect is removed the cause should vanish too... but still it is quite confusing.. So please tell me where does this energy go, if it actually goes somewhere?? Looking forward to your reply.. Any help is appreciated.