A skydiver has her parachute open and gently falls straight down to earth at a constant velocity for 30 seconds. Which one of the following statements is true for these 30 seconds? AND WHY?
(a)The difference between the gravitational force and air resistance is responsible for the downward velocity.
(b) Only the vertical forces acting on the skydiver are unbalanced.
(c) All the forces on the skydiver are balanced.
(d) Only the horizontal forces acting on the sky diver are unbalanced.
(e) None of the above is true.
Please help and answer why :