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Uploaded:2017-02-16
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What if your basic at-the-office elevator ride takes a sudden turn for the dark side of gravity—could you survive it?

Hosted by: Michael Aranda
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Sources:
http://www.livescience.com/33445-how-survive-falling-elevator.html
http://www.popularmechanics.com/science/a247/1289266/
http://wpo.st/-wFS2
https://www.scientificamerican.com/article/how-do-elevators-work/
http://discoverykids.com/articles/how-do-elevators-work/
http://survivor-story.com/betty-lou-oliver-survived-two-major-accidents-day/
http://www.discovery.com/tv-shows/mythbusters/mythbusters-database/jump-in-falling-elevator/
http://www.newyorker.com/magazine/2008/04/21/up-and-then-down

Images:
https://commons.wikimedia.org/wiki/File%3AElevator_hoist_ropes_on_top_of_Lift_car.jpg
https://commons.wikimedia.org/wiki/File%3ALift_shaft_of_a_hydraulic_elevator.jpg
https://commons.wikimedia.org/wiki/File%3AMRL_elevator_(Ropes_to_the_right).JPG
https://commons.wikimedia.org/wiki/File%3AElevator_counterweight_-_Washington_Monument%2C_High_ground_West_of_Fifteenth_Street%2C_Northwest%2C_between_Independence_and_Constitution_Avenues%2C_Washington%2C_District_of_Columbia%2C_DC_HABS_DC%2CWASH%2C2-107.tif
https://commons.wikimedia.org/wiki/File%3AEmpire_State_Building_-_panoramio_(1).jpg
Michael: So you’re in an elevator, just scrolling through your text messages as it zooms past the 15th floor. And then, suddenly, the elevator stops. That’s when you realize that you’re suspended in midair, and you’re really high up. Maybe that’s when you start to wonder: could your elevator start plummeting to the ground any second now? And if it falls, could you survive it?

The good news is that the elevator almost definitely won’t fall. There are lots of safety features designed to prevent a plunge, including multiple ropes and brakes. And if absolutely everything fails, then there are ways to minimize the damage by distributing the impact all across your body. But there’s no guarantee that you’d survive.

In buildings with more than a few floors, the elevators are usually traction elevators. These work by attaching the car to metal ropes or belts and threading them through a motor, with counterweights on the other end of the cable. When the motor is active, it slowly threads cable through, moving the car up or down.

If something goes wrong with the motor, the brakes stop the car. There are different kinds of brakes, but two common brakes are found in the motor and under the car. The brakes in the motor will make the cables jam and stop as soon as the power goes off.Meanwhile, the brakes under the car are usually designed to detect if the car’s moving too fast. If it is, the brakes release a metal wedge into the rails along the elevator shaft. The friction between the wedge and the rail is strong enough to slow the car down and eventually make it stop.

So if the motor suddenly stopped working, the brakes would suddenly start working. It’s incredibly unlikely that both the motor and all the brakes would fail. But if they did, that’s when the counterweights would come into play.

The counterweights are on the other side of the metal cable, and they’re normally about the weight of the elevator car when it’s half full. In the best case scenario, you’d have the right number of people in the elevator so that it exactly balances the counterweight -- so if you’re really lucky, you might not move at all.

And if you’re alone in the elevator, you might actually be lighter than the counterweights, and start moving upward — though that can still be dangerous if the car is moving too fast when it crashes into the top of the elevator shaft.

If it’s a full car, you’ll probably be heavier than the counterweights, and start moving down. In either situation, the counterweights balance out some of the acceleration from gravity. By the time you reach the top or bottom of the elevator shaft, you won’t be moving as fast as you would otherwise.

But a lot of the time you can still expect a pretty dangerous drop -- especially if you’re a long way from the end of the elevator shaft. There’s also the possibility that the brakes fail and the cables snap, but there are hardly any known cases of that happening. Most elevators have multiple cables, and every single cable is designed to be able to hold the weight of a full car.

In fact, it’s pretty common for elevators to have up to eight cables, and with a safety factor of 12 -- meaning that all the cables together can hold a weight equivalent to 12 times the weight of a fully-loaded car. So even if a cable did break, you’d have others holding you up.

There’s one famous case where an elevator’s brakes failed and its cables snapped — it happened in 1945, when a pilot accidentally crashed his plane into the Empire State Building. A woman named Betty Lou Oliver was told to get in an elevator to get out of the building. But the cables were weakened by fire, and they snapped. Oliver and the car fell over 75 stories to the basement. And... Oliver survived.

It’s not clear exactly how she survived, but one possibility is that the car was moving so fast that it compressed the air below to the point where it actually cushioned her fall. Another possible explanation is that all the broken cables piled up at the bottom of the shaft and softened the impact. Whatever happened, the elevator basically had a built-in safety net.

But back to your stuck elevator on the 15th floor. You’re still worried that it might fall, even though you know that’s super unlikely. If it does, you might’ve heard that you’re more likely to survive if you jump just before you hit the ground. But there are two main problems with that idea.

First, the timing has to be absolutely perfect, so that you’re jumping exactly when the car hits the ground. And second, you’d need to have an exceptionally strong jump. Chances are you’re moving really, really, fast, and your jump won’t be powerful enough to make a difference in your speed when you hit the ground.

So a more realistic option might be to lay your body against the floor. Even that can be tricky. If the ropes are broken and you’re in free fall, you’ll feel weightless and it’ll be hard to pull yourself to the floor. But if you manage to do that, then the impact will be distributed more evenly across your body. It’s not a guarantee you’ll survive, but it might be your best shot.

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