I did the math for you guys. Kai from the legend of Korra fell for ten seconds, meaning, that according to the rules of gravitational equations, he fell about 500 meters, at an apparent speed on the impact of 100 meters per second. The gravitational force would be about 400 Newtons. Factoring in air resistance would make it I think 200 Newtons (still a lot), making the acceleration down really just half the normal acceleration. Also, the kinetic energy on impact would be 200,000 Joules or 200 kilojoules. 200 kilojoules are by far enough to kill him, and I don't see how he lived. Btw, he was unconscious while falling so that rules out airbending his way out of the situation.
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