1. The problem statement, all variables and given/known data A well-known paradox is that the air friction due to the outer layer of the earth's atmosphere will reduce the total energy of the satellite and therefore the satellite will move slower. But it is observed that the satellite actually moves faster. Try to explain this phenomenon. 3. The attempt at a solution When the satellite is moving in a lower orbit, some gravitational potential energy of satellite is converted to KE of satellite, so KE of satellite increase and it moves faster when it travels to the earth from space. Total energy decrease because some of the gPE of satellite is lost from satellite. I've checked the answer. The answer said that gPE is converted to KE and KE gain of satellite is larger than KE loss due to air friction, so KE increases and it moves faster. In fact, is all gPE are converted to KE? Is there a part of gPE lost from the satellite? Thank you very much!