During a high-altitude low opening (HALO) parachute jump, the skydiver achieves a terminal velocity of 213 km/h and waits to open his chute at an altitude of 688 m, accelerates uniformly (with a negative acceleration), and lands with a speed of 20.7 km/h. (Assume the negative direction is downward.) a) What is the acceleration of the skydiver (in m/s2) after the parachute is opened? (Indicate the direction with the sign of your answer.)
b) How much time (in s) elapses between the opening of the chute and the landing?
c) Originally developed for the military, HALO jumps are now part of the burgeoning sport of speed skydiving, in which the skydiver attempts to achieve a very high terminal velocity by diving head-first instead of the traditional belly-to-earth posture. Skydivers have been known to reach a terminal velocity of 462 km/h in this manner. If 5g is the greatest magnitude of acceleration for which the skydiver can remain conscious, what is the minimum altitude (in m) at which the chute must be opened in such a jump, if the skydiver wants to land on the ground at 20.7 km/h?