A man 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 n, 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
gravity no longer acts on him.
2. None of these
3. Since he is falling at constant velocity the
force of air resistance no longer acts on him.
4. The same two forces act on him as before;
the only change is that with the parachute
open, the two forces sum to zero.
5. When the parachute opens there is an
additional force n, which has nothing to do
with either n, or mg