“Watch out for elevator cable breaks or getting stuck…”. With this concern, many people avoid elevators or develop a fear of them. But what is the reality?
Imagine this: you are in an elevator, but suddenly it stops, and somehow the cable breaks, causing you to fall freely.
This scenario is all too familiar in Hollywood action and horror films. But here’s a brief question: can you survive if you jump at the right moment when the elevator hits the ground?
Your chances of survival depend on the height of the fall.
A little math can clarify this. Just before hitting the ground, the elevator is falling at a speed of x, while you jump up at a speed of y in the opposite direction. When you jump, you will also fall back down, so your speed upon impact will be “x – y”.
Here, “y” is not a highly variable number, as a person’s jump height is limited. However, “x” is different; it depends on the height from which the elevator starts to fall, making it a crucial factor in whether your jump will be effective.
Survival Depends on Height!
Optimistically, let’s assume you have the jump ability of an NBA athlete, meaning you can jump about 70 cm high. Below is your chance of survival based on the height of the fall.
- 3m (2-story building): If you jump at the right moment, you will land as if you fell from a height of 80 cm, which is not dangerous. The challenge is that you only have about 0.8 seconds to react.
- 9m (4-story building): Free falling from 9m, your chances of death are high. However, if you jump at the right moment, your landing speed will be equivalent to a fall from 4.7m, changing your status from “could die” to “injured.” You might break a few bones but would still be alive, with only 1.2 seconds to act.
- 15m (6-story building): Jumping at the right time will be similar to falling from 9m. Your likelihood of death is high, but your status shifts from “certain death” to “possible death.” You have 1.7 seconds to react.
- 21m (8-story building): Your landing speed will be comparable to a free fall from about 14m. Whether you jump or not, it’s almost certain you will die, and you only have about 2 seconds to prepare.
Should You Jump or Not?
Jumping is very difficult because gravity tends to pull the floor away from you.
In theory, jumping at the right moment when the elevator falls does increase your chances of survival. However, in practice, achieving this is extremely challenging.
Being 1 second late means you will hit the ground; being 1 second early could result in hitting the elevator ceiling, or your jump speed may decrease significantly, making the jump less effective. Even simply jumping is very difficult since gravity pulls the floor away from you. To jump, you need to grip onto something to keep your feet grounded.
So, should you jump? This question remains a topic of debate even among scientists.
Some argue that when the elevator falls, you should lie flat on the floor to distribute the force more broadly across your body. However, others counter that this also means you are leaving space for the force to impact your brain. In that case, it might be better to take the risk of jumping to have your legs absorb the impact instead.
What Happens If the Elevator Cable Breaks?
In reality, elevators are among the safest modes of transportation. This is because they rely on steel cables, usually ranging from four to eight in number.
Therefore, if one cable breaks, the others can still hold the elevator. These cables are designed to withstand the weight of the elevator when fully loaded with people. Thus, the risk of cable breakage due to overloading is very low.
Even if several cables were to break in a rare incident, elevators are equipped with multiple safety layers to protect passengers.
In the 19th century, Elisha Otis, an American industrialist, developed a safety device to prevent elevators from falling if the hoisting cable fails. If the power is cut, the electronic brake can still function.
Hydraulic shock absorbers are typically installed at the top and bottom of the shaft to make the ascent or descent smoother.
With so many safety layers, why do accidents still occur? Reports indicate that most accidents result from human error rather than purely mechanical failure of the elevator.
In the 2018 incident in Chicago, it was clear that many safety precautions were in place. That’s why six people in the elevator fell 84 floors without serious injuries.
Don’t Worry Too Much
Free-fall elevator accidents are now very rare. This is simply because modern elevators have numerous backup systems, such as multiple cables or electromagnetic brakes. Overall, the chances of finding yourself in a real-life action movie are very low, so rest assured.
