People have been arguing about whether toilet paper should be put in or out for decades.

If one day you forget to bring your cell phone when you are in the pit, you might as well pick up toilet paper and study it when you are bored.

It would be better if there were Sudoku on the roll. | | Pixabay |

Don't underestimate the roll of paper you put in the bathroom. We may be able to learn math with toilet paper. What is even more outrageous is that people have been arguing for decades about how to put a roll of toilet paper.

How long is a roll of toilet paper?

If you want to know how long a roll of toilet paper is, what's your idea? apart from taking apart a roll of toilet paper the way your mother sees it, maybe you can try to do the math next time.

If you want to know how long a roll of toilet paper is, I be like toilet paper | Giphy

In the eyes of the math teacher, this is just a simple calculus problem. Learn to calculate this problem, and the next time you squat, you can easily figure out how long toilet paper is left in your home.

From the most basic start, we can think of toilet paper as a paper tube with a radius of R, which is wrapped with n layers of paper, which can be seen as a set of n-layer rings. The total thickness of the paper is D. The thickness of a piece of paper is h.

So the radius of the first layer is R1mm R, the second layer R2=R+h, the third layer R3=R+2h, and the I layer becomes Ri=R+ (iMel 1) h.

So, to figure out the total length L1 of the paper, we just need to figure out the perimeter of each circle and add them up. Isn't it very simple.

A simple summation problem (omitting the intermediate calculation process)

However, the situation of the paper roll is more complicated than this, because as the paper is constantly wound, the radius of the ring increases. Instead of seeing it as a layer-by-layer ring, it is better to directly regard it as a helix and calculate the total length of the helix through the angle of rotation. Then add up all the angles of the tissue.

At this point, we have a formula for calculating the length of the paper, and we just need to replace the values that are easy to measure.

. You can pull it directly below to see the answer.

It is worth noting that if you find it difficult to calculate how thick a piece of paper is, you can stack 20 pieces of toilet paper together and divide it by 20.

There are always more ways than difficulties! | | Giphy |

A roll of standard toilet paper (barrel radius 55mm, paper thickness 20mm, sheet thickness 0.36mm), paper length is approximately 22907mm. You can also take a ruler to the bathroom and calculate the length of toilet paper in your home.

After verification, the result is exactly the same! | bring science home for live shooting.

Is it useful to use toilet paper to learn simple modeling and calculus? mom will take you to the bathroom all night.

How do you put your toilet paper roll?

Do you put your toilet paper roll in or out? why?

In 1986, columnist Landers said publicly in the magazine that toilet paper rolls should be put in. As a result, her views were so controversial that Landers received a total of 15000 letters that year to discuss the issue.

For decades, people have been arguing about this issue, and everyone has a variety of reasons, from aesthetics to comfort, convenience and so on.

Fight! Fight!

People who put it out feel that it is more convenient to take out the number of frames they want. And if the paper roll is placed inward, it is easy to touch the wall and be stained with bacteria and dust when you take it.

Those who put it inward think that hiding the end of the toilet paper will be cleaner and prevent children or pets from pulling a whole roll of paper apart.

Perform a roll of paper vanishing art! | | Giphy |

In various surveys, on average, about 30% of people choose to put it inward, and about 70% choose to put it outward.

If you happen to meet someone who agrees with you, you may be really lucky, because it will avoid some disputes. A survey shows that quarrels over where toilet paper is headed can really affect mood in families, companies and public places.

The survey found that couples really quarrel over this issue. When dozens of people lived together at the Amundsen-Scott South Pole Station, people complained about where the toilet paper was headed.

Toilet paper: it's none of my business, don't cue | Pixabay

Of the more than 700 people who put toilet paper facing out, 24% were annoyed because they were going in the wrong direction, and 27% would correct the orientation of toilet paper in a friend's bathroom.

If you think this question is ridiculous, then. Otherwise, whether the toilet paper should be placed outward or inward, whether to wash your hair or take a bath first, and whether the socks should be rolled outward or inward seem to be very suitable for consideration when going to the toilet.

It is precisely because of this, but also spawned some more intimate designs. For example, there are two paper shelves in the toilet, one facing inward and the other facing outward, which does not affect each other. Or rotating toilet paper rack, automatic paper dispenser and so on.

For the sake of world peace, we have to put two toilet paper shelves. | | Wiki |

Everyone's way of taking paper is unique.

We have to admit that toilets are closely related to our health. We can see a person's eating habits, intestinal health and kidney disease from the toilet. So in the future, toilets may be an important place to collect personal health data.

But there is also a problem: because toilets are often shared by several people, if you want to collect information, user identification has become an important issue.

Many health indicators can be seen from the toilet. | | Pixabay |

It certainly won't work to install cameras and microphones in the toilet because of personal privacy. It doesn't seem reasonable to enter personal information manually every time you go to the bathroom. Scientists have also proposed that everyone's DNA can be extracted from feces, but this is time-consuming and expensive and cannot be easily achieved.

Some Japanese scientists have proposed that we can identify people who go to the toilet by pulling toilet paper.

They take into account that in a private space like the bathroom, everyone may have a unique way to get paper. So they put wireless gyroscopes into toilet paper shelves to measure the angular velocity of pulling toilet paper, and after a large amount of data training, sensors can identify who went to the toilet.

It turns out that in the actual scene of a house of five, the recognition accuracy of the gyroscope sensor is 69.2%. However, the amount of data is still too small, and with more data training, the device can identify it more accurately.

I can tell who you are by pulling the roll. | | Giphy |

Although it doesn't seem to be of much use, going to the bathroom is a serious thing, and rolling paper can be regarded as a great invention. After going to the toilet, ancient people used various materials such as leaves, grass, shells or moss to clean themselves, and it was not until the 19th century that paper rolls came to the assembly line. People also make toilet paper more comfortable, durable and environmentally friendly by embossing and improving materials.

Even if you don't have a cell phone when you go to the bathroom, you can take a look at the roll of paper, and you may be able to play with flowers.

It's a real game.

A cold knowledge: tissue paper (all kinds of tissue paper) and toilet paper (roll paper) are two kinds of paper. In addition to the difference between roll and non-roll, in fact, the hygiene standards of the two kinds of paper are different.