skydivers, flying over sea-level ground, typically jump at about 8000 ft altitude and freefall spread-eagled until they open their chutes at about 2000 ft. they take about 10 s to reach terminal velocity. estimate how many seconds of free-fall they enjoy if (a) they fall spread-eagled or (b) they fall feet first? assume a total skydiver weight of 220 lbf.