About 16 seconds -- ignoring air resistance.
https://www.foxnews.com/us/man-falls-4000-feet-grand-canyon-skywalk-death
About 345 mph, again, ignoring air resistance.
https://www.foxnews.com/us/man-falls-4000-feet-grand-canyon-skywalk-death
About 345 mph, again, ignoring air resistance.