Eli5: What would happen if I pour water out of a bottle in a falling Elevator?


What would happen? Would the water hit the roof of the elevator since the elevator is falling rapidly?

I thought about it when I put Eye Drops in an elevator.

In: Physics

Nah, it hit the floor. The elevator would need to be in free fall (or close to) for it to hit the roof.

You’re just not moving fast enough.

Once the elevator is moving, the water will pour like normal because gravity is going to affect it at the same rate regardless of how fast it is already moving.

If the elevator is rapidly accelerating downwards, the water might hit the roof, but if the elevator is moving at a consistent rate (or not accelerating that much) the water would act like you were standing stationary.

If the elevator were falling for long enough to reach terminal velocity would the water not just stay in the bottle or at most trickle out? That would make sense to me anyway.

If you hit the ceiling then the water will hit the ceiling. If the elevator is free falling then you might feel weightless so you and the water wouldn’t move. In normal operation the water goes to the floor like you.

Several problems

Elevators fall upward. If everything were to fail it would go up because the counterbalance weighs more than the car up to the max weight.

Elevators have brakes

If they move past the speed the motor can handle, the brakes engage

Elevators are on a track that has friction greater than 0. Even if all the aforementioned things failed and the cable somehow was severed, the elevator wouldn’t be able to reach freefall speed, so the water would always be able to hit the bottom of the car.

If the elevator were supported or falling through air (which would slow down the elevator), it would still hit the ground.

If it was in free fall and there was no air to slow it down, the water would neither hit the ceiling or the wall it would float. [Exactly like this.](https://youtu.be/o8TssbmY-GM?t=101)
The International Space Station is constantly falling. It’s just moving so quickly to the side that it keeps missing the earth. This is called an orbit.

The only way it hits the ceiling is if something like a rocket is pushing it downwards faster than gravity.

You would have an elevator with a wet floor. Careful not to slip.

Elevators don’t descend anywhere near fast enough to counteract the force of gravity. Moving that fast would be dangerous to the unrestrained human occupants. If you aren’t experiencing weightlessness or hitting the roof in an elevator water wouldn’t either, these things are both the same in terms of the physics involved.

This thread has a lot of overcomplicated answers that make a bunch of assumptions.

If you are in a free falling elevator and you disregard friction, you are accelerating at 9.8m/s^2, which is gravitational acceleration (1g). The water in this case would float in mid air as though you’re in space. This is the same principle as zero-g airplane flights, which enter a free fall to simulate a zero-g environment for a short period.

The reason this happens is because when you’re holding your bottle of water in the free falling elevator, it’s already accelerating downward at 1g. Pouring it out doesn’t make it fall any faster. It will continue accellerating at 1g, but it will be outside the bottle. If the elevator comes to a stop, the water will fall to the floor.

I think the elevator part is confusing people. If you jump out of a plane and spill some water at the same time, you and the water will fall at roughly the same speed

The water will fall on the floor.

The two questions that are important here is ‘how fast does water fall?’ and ‘how fast do elevators move?’

A droplet of water has a terminal velocity of around 10 meters per second – the terminal velocity being the fastest it will fall under the force of gravity.

An average elevator may travel at a speed of around 1m/s.

What this means is that if you hold your bottle a meter above the floor, and pour out some water, it will take about 1/10th of a second for it to fall and hit the floor. During this 1/10th of a second however, the elevator will have continued descending, around 0.1m which the water will have to fall.

So it will take longer for the water to hit the ground of an elevator if you pour it out while descending (and conversely, less time if the elevator is rising), but only a tiny fraction of a second (about 1/100th second longer).

If you want your water to float, you would need the elevator to be moving at a speed equal to the terminal velocity of water.

It depends if your falling faster or slower than the rate that water falls at. If the lavatory is falling faster than the water would be if you poured it out then the water would go up but if it’s a slow elevator fall then the water would go to floor like normal. Same way that if you jump while an elevator is falling very quickly you will go to the ceiling of the elevator

Einstein once said that his most happy thought was that of a man falling off a high building.. This wasn’t some morbid did entertainment from another Man’s demise. He thought it was neat that everything that everything that fell along with him would essentially be weightless from his perspective.

So for the water to hit the roof, the acceleration of the elevator has to be greater than the acceleration due to gravity. this is because the water in the bottle will leave it at the same speed as the elevator, and will accelerate at the acceleration due to gravity. So if the water and the elevator both fell at the same speed then the water would appear to float with respect to the elevator, but if the elevator is accelerating faster then the water than the water would hit the roof.

However, in most situations, the elevator is also subject to friction due to it’s rails and other mechanisms, so the water will fall on the floor.

This experiment is sort of done commonly on the Drop towers that are at popular amusement parks.

Power Tower at Cedar Point is a big one on physics day to show stuff like this. usually with someone holding a plastic tube filled with something. a object or water, bubble. I tried looking on youtube for the video but the quality was baddd