So if you time it perfectly, the elevator would hit the floor but since you were in the air, you don’t feel the pressure of the landing. And then you wouldn’t get injured, right?
In: Physics
You’d still be falling at mostly the same speed as the elevator. You’re probably falling downwards much faster than you can jump upwards, so if you could jump up, you’re only reducing your downwards motion by a fraction. So, you’d jump up and hit the ground a fraction of a second later, at maybe 5 mph slower.
*Also, if the elevator and you are both in free-fall, it’s going to be harder to put full force behind a jump, since there’s no force pushing your feet against the floor.
In theory you could reduce the impact slightly.
In reality it has been shown that the reduction in impact would be very slight, and not enough to offset the other issues of the technique.
For example you would need to time your jump with split second perfection, while in an enclosed box with no point of reference to tell you when the impact will be – jump slightly to early or late and you will increase the impact force and hurt yourself more.
By jumping you also risk striking the roof of the elevator as it stops from the impact, or getting thrown around if it doesn’t stop evenly.
Instead, lay flat on the floor so the impact is spread over your whole body rather than directed completely through your ankles and legs, and relax so that your body is loose and more able to absorb the impact without damage.
In reality it is also notable that it is incredibly unlikely an elevator will ever fail so critically. They come with multiple failsafes to prevent a fall such as multiple redundancy in the cables that support the car, automatic brakes to stop the car in the event of a free fall, and the fact that an enclosed lift shaft can actually act like an air piston to slow the car as it reaches the bottom.
Others have talked about how your speed change would be minimal but there is another reason jumping would make things worse.
At the bottom of the elevator shaft there are shock absorbers. These make the transition from full speed to zero spread out over time. Without the shock absorbers, the elevator (and you) would go from 100 mph (or whatever) to zero in let’s say a millisecond – that’s around 5000g’s, which would kill you. If that deceleration is spread over a second, it’s only 5 g’s which is much more survivable. (I made up the numbers but the principal is sound).
If you jump before hitting the ground, you lose the benefit of the shock absorbers. The elevator comes to a stop and then you hit it all in one go.
This is the same reason, by the way, that it is important to attach car baby seats tightly, and tighten the belts around the baby snugly – in case of a crash, you want the “gradual” slowdown provided by the car’s crumple zones to be transferred to the baby.
If you can jump with enough force to match the speed of the falling elevator, yes.
That does mean, though, that your legs would have to accelerate you at the same speed that they’d have to absorb in the crash, which only means that you’d kill yourself rather than wait for the impact to do it…
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