I assumed that your timing is perfect, despite probably being unable to see the ground. This Mythbusters episode showed that this is very difficult. I assume that you are able to effectively push off the floor as you jump, which is challenging because gravity is pulling the floor of the elevator away from you. If you are suddenly in free fall, you will need to grab a hand rail to keep contact with the floor. Others have been crushed when the enormous broken cable above landed on the top of the elevator.
However, air can save you in another way. Trapped air in the shaft below the elevator may provide an additional cushion. Suppose we drop the elevator from 7 storeys again. If the shaft were perfectly sealed like a piston, the elevator would only drop 50cm before the extra pressure of the compressed air supported its weight.
But there is usually a gap between the shaft and the elevator, which allows the cushion to deflate. If you go through the kinematic equations neglecting air resistance , you can indeed show that your ground impact velocity is minimized by jumping close to the last second.
If you jump exactly at the last moment, the platform will not have time to receive your momentum, and hit the ground. So it is best to jump close to the last moment. Simple mathematics show that near impact your impact velocity is just your free-fall-acquired final velocity minus your jump velocity. Your jump velocity is how much upward velocity you gain by pushing away the platform. Assuming the maximum human jump velocity to be 7 mph, if your platform fell from 33 feet about three floors , you would reduce your impact velocity from 31 mph to 25 mph by pushing the platform down with all your might near the last moment possible.
If you fell from feet about 15 floors , pushing at the right moment would reduce your impact velocity from 72 mph to 65 mph. Of course, the actual damage depend not only on your impact velocity, but also on the solidity of the ground. Common Elevator Myths and Truths:. There are many myths and misconceptions about elevators. This is because the majority of all elevator equipment is hidden from public view, which thus leaves much to the imagination of a passenger. The following are some of the most common myths and their corresponding truths:.
MYTH - Many people believe elevators are held up by only one rope that can break, leaving passengers in a free falling car. Each cable alone can support a fully loaded car.
MYTH - Some people believe that an overcrowded elevator will fall. The doors will stay open and a buzzer may ring until enough people get off of the elevator to reduce the weight. Elevator experts believe people may think this has happened as a result of the following: They boarded an elevator that was traveling in the opposite direction they thought it was traveling.
They saw the elevator floor indicator lights flash by quickly which gave the visual impression of falling. In fact, just one cable is usually enough. But let's say all the cables did snap. Then the elevator's safeties would kick in. Safeties are braking systems on the elevator car that grab onto the rails running up and down the elevator shaft.
Some safeties clamp the rails, while others drive a wedge into notches in the rails. Typically, safeties are activated by a mechanical speed governor. The governor is a pulley that rotates when the elevator moves. When the governor spins too fast, the centrifugal force activates the braking system. If the safeties failed, you would be plummeting rapidly, but you wouldn't quite be in a free fall.
Friction from the rails along the shaft and pressure from the air underneath the car would slow the car down considerably you would feel lighter than normal though. On impact, the car would stop and you would keep going, slamming you into the floor. But two things would cushion the blow. First, the elevator car would compress the air at the bottom of the shaft as it fell, just as a piston compresses air in a bicycle pump. The air pressure would slow the elevator car down.
Second, most cable elevators have a built-in shock absorber at the bottom of the shaft — typically a piston in an oil-filled cylinder. That would cushion the impact too.
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