(published on 10/22/2007)
(published on 10/22/2007)
(published on 05/16/2013)
(published on 05/16/2013)
(published on 06/03/2009)
(published on 09/26/2011)
If you didn't jump, your speed would be sqrt(2g*10m)=14 m/s.
Let's say that you jump just before hitting in a way that would give 0.5 m height in a non-accelerating elevator. (That may be hard to do in free-fall, but let's pretend.) That means an upward velocity (in the elevator frame) of sqrt(2g*0.5m)=3.1m/s. So you'll have reduced your velocity at that height to 10.9 m/s.
Why is it hard to jump in free-fall? Ordinarily, you and the floor exert a force on each other equal to your weight. You can bend your knees, and gravity will keep you in contact with the floor. Then rapidly unbending your knees exerts extra force between you and the floor, and you jump up. In free fall, if you bend your knees your feet will just pull up a bit from the floor as your upper body pulls down a bit. Unless your knees happened to be bent at the start of the free-fall you'd have to somehow stretch out to jump. That's unlikely to give a powerful jump.
Mike W.
(published on 06/02/2013)
(published on 10/22/2007)