# Water Bottle Experiment (not that of Newton's)

• abejackson
In summary, for an experiment involving a plastic bottle with four holes covered by tape and filled with water, the flow of water is initially stronger due to the greater mass of water and higher pressure exerted by the depth of the water. As the water drains, the pressure and flow decrease. The formula for pressure in liquids is P = P. + pgd, where P is pressure, P. is the pressure at the surface, p is the density of the fluid, g is gravity, and d is the distance or depth of the water. This pressure difference on the two sides of the holes causes the water to flow out, but as the depth decreases, the pressure difference also decreases and the flow slows down. The summary also includes additional
abejackson

## Homework Statement

I have to submit a report based on this following experiment.
I have a plastic bottle with 4 holes located about 1cm above the base of the bottle. The four holes are covered with tape. I'm to fill the bottle with water and observe the flow of water coming out of the holes when I release the tape. I did this experiment and the flow of water was stronger,with some resistance to the gravity, at the beginning and gradually dies down until the container became empty. I will have to write a one-page report about this experiment, explaining how the water flows out of the bottle and what my observations say about the pressure the water exerting on the wall of the bottle.

## The Attempt at a Solution

I'm thinking of Newton's 3 laws and I would suggest that the flow of the water inside the bottle is stronger initially due to the more mass. (F=MA) As the bottle drains the water, the total mass inside the bottle become lighter and the total force becomes weaker.

I would like to know how I can elaborate on my explanation.
I'm taking a introductory physics course (for humanities students). Thank you.

For this experiment, Let's take a look at the formula for pressure in liquids.

P = P. + pgd

P = Pressure (in pascals
P. = Pressure at the surface of the liquid (generally 101,325 Pa at sea level)
p(greek letter rho) = the density of the fluid (for water it is 1000)
g = gravity (9.81 m/s/s)
d = distance (height, or depth of the water)

So looking at the formula, when the depth/height of the column of water increases, what is going to happen to the pressure on the water near the holes?

I hope this clears up the concept, if not let me know.

Hi WolfeSieben,
Thanks for your comment and effort.
I forgot to mention one important piece of information.
I'm supposed to write so that it would be understandable by non-scientist. As a physics course for humanities students, math has completely taken out of the equation. I know that it's kind of weird to talk about physics without math. I looked at the equation you wrote and I guess the pressure has to be the initially. Thanks.

Last edited:
Okay, Well to explain this concept without using the equation is also possible.

As the height/depth of the water increases, the pressure applied near the holes is higher, because there is more pressure pushing down on the liquid at the depth of the holes. as this water drains, the pressure drops. this is why the liquid will move further when the bottle has more water in it, because it has a greater depth.

Essentially it is because the water creates a greater pressure on it's self, the deeper it is.

(Mathematically, that's why there is a variable for the depth/height in the equation.)

Does this explanation help?

Yes. Thanks a lot. The reason why I'm taking this course is to do some prep work to physics major. I decided to major in physics but thought that I have to some catching up before diving into college-level physics and math. What about you? Did you do physics in college or are you doing physics in college now?

You're more than welcome,
I've gotten a lot of help from the other members here so it is my pleasure to give back when I can.

I'm actually a Premed student double majoring in Biological Sciences and Chemistry. I'm in my 4th year, but I also love physics, so I am doing several courses in it as well. I'm not as well versed in it as my other two fields, but I'm taking all the first, and some of the second year courses offered.

the water comes out because of the pressure difference on the two sides of the hole.
the flow slows down because the pressure difference becomes smaller over time

## 1. How does the water bottle experiment work?

The water bottle experiment involves creating a vacuum by partially filling a bottle with water, flipping it upside down, and submerging the opening in a container of water. The air pressure outside the bottle pushes the water up and prevents the water from escaping, creating a vacuum inside the bottle.

## 2. What supplies do I need for the water bottle experiment?

You will need a plastic water bottle, water, a container filled with water, and a flat surface to conduct the experiment on.

## 3. What is the purpose of the water bottle experiment?

The purpose of the water bottle experiment is to demonstrate the effects of air pressure and create a vacuum using everyday household items.

## 4. How can I modify the water bottle experiment?

There are several variations of the water bottle experiment, including using different liquids, using different shapes and sizes of bottles, and adding food coloring or objects to the water for visual effects.

## 5. What safety precautions should I take when conducting the water bottle experiment?

It is important to use caution when handling the water bottle experiment, as the bottle can break and cause injury if dropped. Additionally, be careful when flipping the bottle upside down to avoid spilling the water. It is also recommended to conduct the experiment in a sink or outside to prevent water from spilling onto surfaces.

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