Consider a dam, in that first the hydraulic energy due to gravitational force gets converted into mechanical energy by using turbine. Then those mechanical energy is converted into electrical energy by generator which gives the electricity to the whole area. Then we use fans , coolers, TV etc,. which gives mechanical energy to the fan. As we know energy can neither be created nor destroyed but just keep changing its form, my question is now after mechanical energy what does it convert into?

• Heat ${}{}{}{}{}$ – John Rennie Jul 20 '15 at 17:02
• kinetic energy of air molecules, light from a tv, heat from a heater. But invariably, as John pointed out, almost all the energy we consume is turned into heat energy (some of it stays as light forever) – Jim Jul 20 '15 at 17:04