X 3.4.7 Question Help A parachutist whose mass is 85 kg drops from a helicopter hovering 2000 m above the ground and falls toward the ground under the influence of gravity. Assume that the force due to air resistance is proportional to the velocity of the parachutist, with the proportionality constant by 30 N-sec/m when the chute is closed and b₂ = 90 N-sec/m when the chute is open. If the chute does not open until the velocity of the parachutist reaches 20 m/sec, after how many seconds will the parachutist reach the ground? Assume that the acceleration due to gravity is 9.81 m/sec? The parachutist will reach the ground after (Round to two decimal places as needed.). seconds.