A skydiver jumps from a ballon and falls freely for 6 seconds. Her parachute then opens ,decelerating her at a constant rate of 3 seconds to a velocity of 18 ft/s,which she maintains until she lands.(Neglect air resistance during the free fall.) If the skydiver jumped from an elevation of 6000ft, determine (a) her maximum velocity and (b) the total time elapsed during her travel from the ballon to the ground.