There were two posts reltaed to this question but both of them are so contradictory; the question goes a 13,000kg helicopter accelerates upward at 0.41m/s^2 while lifting a 900kg car. to the nearest newton what is the lift force exerted by the air on the rotors? now one post would be Fnet = (13000)(9.8) + (900)(9.8) which in a sense is what we are looking for (but unfortunately, is wrong for some reason) and so i don't know what piece of hte puzzple im missing; im sure the 0.41m/s^2 comes in at some point. Is it the force required to accerleate the helicopter? If so what would that be.. im lost.