Aman jumps from an airplane and does not open his parachute immediately. as he falls, two forces act on him: the force mg due to gravity and the force na of air resistance. now he opens his parachute and begins to fall at constant velocity what forces act upon him now? 1. since he is falling at constant velocity the force of air resistance no longer acts on him. 2. the same two forces act on him as before the only change is that with the parachute open, the two forces sum to zero. 3. when the parachute opens there is an additional force np which has nothing to do with either na or mg. 4. since he is falling at constant velocity gravity no longer acts on him. 5. none of these