Many people still don't know the cold knowledge of plastic bottles!

Today, let's learn about a very common thing around us - mineral water bottles.
What scientific knowledge can we know from mineral water bottles? For example, the space occupied by the water in a mineral water bottle is called the volume of water in the bottle.
Today, let's learn about the structure of mineral water bottles.
To learn science, we need to learn to question and speculate. With an ordinary mineral water bottle, we can actually have doubts.
The more thoughtful and meticulous something is, the better it will win people's favor.
The reason why mineral water bottles use soft plastic is because soft plastic is cheap and not easy to harm people. Moreover, the circular structure of plastic is not suitable for injury and saves materials.
So, why are there patterns on plastic? Mineral water bottles often expand due to thermal expansion, and aerated drinks can also cause horizontal expansion or even explosion. And with patterns, in addition to the above, it will greatly increase the firmness of plastic bottles, and also increase people's visual perception, hand feel, and three-dimensional feeling.
Do you know why the bottom of a plastic bottle is made into a concave shape? That's because plastic bottles often have volume expansion caused by soda shaking, thermal expansion, or water becoming ice (water becoming ice, usually one eleventh of the original volume). If made into a flat bottom, the water bottle will not stand steadily.
Do you know why there is a protrusion at the bottom of a plastic bottle? That's actually the seam of the bottle. If the bottom is not flat, then the bottle will also become unstable.
Do you know why the water in the plastic bottle is not filled? Is it to save money? Of course, there are some possibilities. However, the main reason is due to the same volume expansion as before, otherwise it would explode. If the temperature difference is 30 ℃, the volume of water will change by 5%.
You may have heard this humorous question: "Why doesn't water have a shelf life in nature, but does it have a shelf life when bottled
Of course not! Any object has a so-called expiration date, which is called the shelf life. All objects have the day of death and decay, but it depends on where they are. The water in nature is filtered layer by layer through the soil, and fresh water is buried underground, extending its shelf life. If in a vacuum environment, the shelf life of a substance is very long.