Aman Shaw has the false idea that more energy is taken from a gravity field by a descending weight if the descending weight has some resistance made, for example, by turning a motor to do work; but that it can be raised back up again, restoring the gravitational energy, with less work if there is no resistance to the upward motion. He has been spamming many threads with his "gravity engine" nonsense, total unconcerned that he is suggesting an "over unity" device (get net energy from a closed system). As he does not accept that energy is conserved, (cannot be increased by impossible over unity devices), here is how it has been shown to be false in another thread: If the mass descending in a gravity field has no resistance, for example is falling in a vacuum, then the decrease in its gravitation potential energy, for example 100 joules, is 100% converted into kinetic energy. If it has great resistance, so it takes hours to slide down, straight or curved sheet of sand paper, (or what ever is making great resistance to the fall) then 99.99+% of that same 100J of gravitational energy is converted into heating the sand paper and the mass (or is doing work, but less than 100J, on the resistance device). (There is tiny amount of KE even if the sliding speed is only 1mm/minute so 100% of the decrease in gravitational 100J is converted into some other form of energy.) If the mass is then lifted (with no friction in the, lifting device) back to the starting position where it has the original 100J more of gravitational energy again, then the energy required for lifting it is 100J, but of course there is always some friction (energy loss) in the lifting device (even if it is your right arm) so more than 100J is required to lift the mass back to its starting position.