1. Why is milk sold in square boxes and coke in round bottles?

        Almost all soft drink bottles, whether glass or aluminum, are cylindrical. But milk boxes seem to be square. Square containers can make more economical use of shelf space than cylindrical containers. So why do soft drink manufacturers insist on cylindrical containers?

        One of the reasons may be that most soft drinks are drunk directly in containers, so the extra storage costs brought about by cylindrical containers are offset by the fact that they are more like hands. But milk is not like this, most people will not drink milk directly in the box.

        If the milk container is cylindrical, we need a bigger refrigerator.

        But even if most people drink milk directly from the box, the cost-effectiveness principle suggests that they are unlikely to be sold in cylindrical containers. Yes, square containers (no matter what's in them) do save shelf space, but the space saved in milk is obviously more cost-effective than that in soft drinks. Most soft drinks in supermarkets are on open shelves, which are cheap and usually have no operating costs. However, milk needs to be specially packed in the freezer, which is very expensive and has high operating costs. Therefore, the storage space in the freezer is very valuable, which improves the income of milk filled in square containers.

        2. Why are the portraits on coins All in profile, while the portraits on banknotes are positive?

        If you look at the change in your pocket, you will find that the front president's head on the coin is in profile. Lincoln and Jefferson on the coin and Roosevelt, Washington and Kennedy on the dime are all with their faces on their sides. But on the note in your wallet, you can't find the profile. Washington on the 1 dollar note, Lincoln on the 5 dollar note, Hamilton on the 10 dollar note, Jackson on the 20 dollar note, grant on the 50 dollar bill, and Franklin on the 100 dollar bill are all positive portraits. With very few exceptions, the situation is similar in other countries, with the side image on the coin and the positive image on the note. Why is there such a difference?

        In short, although most painters prefer positive portraits, the technical difficulties in metal engraving make it difficult for people to draw positive portraits with high recognition on coins. The space available for painting on coins is generally only 4 cm square. Due to the lack of fineness, it is difficult to draw a positive portrait that can be easily identified. On the contrary, if only the profile is drawn, it is much easier to recognize the subject. It is technically possible to draw a sufficiently fine frontal portrait on the coin, but it is extremely expensive. At the same time, with the circulation of coins, delicate details soon wear away.

        Since profile images are easier to make and identify, why not use them on paper money? This is because the fineness and complexity of the obverse portrait can prevent the manufacture of counterfeit banknotes.

3. Why do some cars have fuel holes on the driver's side and some on the co driver's side?

        One of the most frustrating experiences of renting a car is that when you park your car in front of the oil pump as usual, you find that the mailbox is on the other side of the body and the oil gun can't reach it. In fact, automobile manufacturers only need to set the fuel hole on one side of the car to solve this problem. But why don't they?

        In the United States and other countries where vehicles drive on the right, it is easier to turn right than to turn left when crossing the street. Therefore, most companies have the opportunity to go to the gas station where they can turn right to enter the station. Assuming that the fuel tank is always on the driver's side of the car, then, in order to refuel, the driver must park the car on the right side of the oil pump. As a result, during rush hours, all the right pumps will be full of cars, while most left facing pumps will not be used. Therefore, the fuel holes of different models are set on different sides, which means that some cars can refuel from the left. So drivers don't have to wait in line for gas. This benefit (benefit) is obviously much higher than the cost of accidentally parking the wrong direction when filling a rental car.

        If the gas holes are on the driver's side, there will be a long queue at the gas station.

        4. Why are the buttons on the left for women's clothes and always on the right for men's clothes?

        According to the different needs of different purchasing groups for the function of clothing, it is not surprising that garment manufacturers adopt corresponding uniform standards. Strangely enough, the standards used by women are the opposite of those used by men. If standards are completely arbitrary, that's another thing. But men's standards are also very suitable for women. After all, more than 90% of the world's people (men and women) are right-handed, and it's much easier to button with the right hand. So, why are women's buttons on the left?

        History has the final say.

        In this case, it seems that history has the final say. In the early 17th century, buttons were the only ones with money. According to the custom at that time, the men dressed themselves, while the women were helped by servants. The button on the lady's shirt is nailed on the left, which greatly facilitates the servants of the hostess (mostly right-handed). The button of men's shirt is on the right, not only because most men wear their own clothes, but also because they pull out the sword hanging on the left waist with the right hand, which is not easy to be caught by the shirt.

        Now there are servants waiting on the ladies to dress. I'm afraid there are few left. Why do women's buttons remain on the left? Once established, norms are difficult to change. Since the buttons of all women's shirts are on the left, it would be very risky for any clothing manufacturer to provide women's shirts with buttons on the right. After all, women have long been used to buttoning from the left, and once the buttons are changed to the right, they have to develop new habits and use new techniques. In addition to this practical difficulty, some women may find it embarrassing to wear a shirt with buttons on the right in public because people who see it will think she is wearing a men's shirt.

        5. Why is it that when you open the refrigerator, the freezer lights up, but the freezer doesn't?

        To answer this question, economists are bound to compare costs and benefits.

        Whether it's in the freezer or the freezer, the cost of installing a light that automatically lights up when you open the door is almost the same. This is what economists call "fixed cost," which means that it doesn't change with the number of times you open or close the refrigerator door. In terms of income, there is a lamp in the cabinet, which makes it easier for you to find things. Since most people open the freezer a lot more times than they open the freezer, it's clear that the benefits of installing a lamp in the freezer are greater. Therefore, since the cost of installing a lamp is the same, then, according to the principle of cost-effectiveness, installing a lamp in a refrigerator is more cost-effective than installing a lamp in a freezer.

        Of course, not all consumers think that installing a light in a freezer is not cost-effective. In general, the higher a person's income is, the more likely he is to be willing to pay for additional features, as measured by who is willing to pay for the benefits of such features. Therefore, the principle of cost-effectiveness tells us that in order to enjoy the convenience brought by lamps in freezers, consumers with super high income may be more willing to spend more. right enough. The pro 48 refrigerator produced by sub zero, a high-end refrigerator manufacturer, not only has lights installed in the freezer, but also has lights on each layer of ice. What's the price of this refrigerator? $14450. Therefore, the pro 48 refrigerator of sub zero is another exception to the principle of cost-effectiveness.

        6. Why can laptops operate under the power supply standards of any country, while most other appliances can't?

        At present, the household electricity provided by the U.S. power system is 110 volts, and in many countries it is 220 volts. The power cord of the laptop has a built-in transformer, which enables the computer to operate normally under both standards. On the contrary, televisions and refrigerators can only operate under one standard. To use an American refrigerator in France, you have to buy a separate transformer to convert the French 220 V power supply to 110 v. Similarly, if you use Korean TV in the United States, you can only buy a transformer to convert 110 V power supply to 220 V power supply in the United States. Why can't these appliances be used everywhere like laptops?

        It's a little cheaper and a little more dangerous to transmit 220 volts than 110 volts. Most countries have conducted extensive demonstration on which transmission system to adopt. Once a decision is made, the state will invest a lot of money into the selected system. Therefore, it is unrealistic in the near future to expect all countries to adopt a unified power supply standard. Therefore, people traveling abroad with electrical appliances need to find ways to ensure that these appliances can be used under different power supply standards.

        It is no doubt that building transformers into all appliances can meet this demand, but it will increase the manufacturing cost of electrical appliances. The vast majority of refrigerators, washing machines, televisions and other electrical appliances will not have the opportunity to travel abroad, so the extra cost of installing built-in transformers for them is not reasonable.

        Especially when the laptop was born. At that time, most of the people who bought laptops were business people who needed to travel around the country and abroad with them. For these people, carrying heavy transformers on international flights is an unacceptable burden. So laptop makers have built transformers in their computers from the beginning.

        7. Why is it necessary to lock the door of a 24-hour convenience store?

        Many convenience stores are open all year round. Since they never close the door, why bother to lock the door?

        Of course, there will always be emergencies, forcing convenience stores to close temporarily. After Hurricane Katrina, for example, residents of New Orleans were forced to evacuate unprepared. Obviously, a convenience store with no staff or locked doors would be a good prey for robbers.

        Even with the exception of emergencies that could close, there's no good in buying an unlocked door at a convenience store.

        The vast majority of industrial doors are sold to places that do not require 24-hour operation. These places, obviously, have reasons to want locks on their doors. Therefore, the first mock exam is to lock the doors, and all doors are made in the same mode. This is the same as Braille on the keyboards of all ATMs (even those installed on high-speed roadsides).

        8. Why is DVD the same size as CD, but DVD box is much bigger than CD box?

        The CD box is 14.8 cm wide and 12.5 cm high. The DVD box is 10.45cm wide and 19.1cm high. Why are CDs the same size but so different in packaging?

        A little digging can reveal the historical source of this difference. Before the advent of digital CDs, most music was sold in the form of vinyl records. The package of vinyl record is 30.2 cm square paper box. The shelf space for vinyl records is just enough for two rows of CD boxes (including the space between them). The CD box is half the width of a previous vinyl record, so retailers don't have to bear the real cost of replacing storage shelves and display counters.

        The same considerations lie behind the DVD packaging. Before the advent of DVD, most rental stores kept VHS video tapes in paper boxes 13.5 cm wide and 19.1 cm high. Video tapes are usually displayed side by side with labels facing out. In the process of consumers gradually switching to DVD, DVD packaging boxes keep the same height, which is convenient for rental stores to display on the existing shelves. In addition, the DVD box is as high as the VHS video box, and consumers will be more willing to put their new DVD under the DVD door because they can put the newly purchased DVD on the shelf where the VHS video tape was stored.

        9. What's the front pocket for?

        Jeans are regarded as the most versatile fashion items. No matter men, women, children, fashion or business, jeans are absolutely indispensable in the wardrobe of people from all walks of life. But do you know what the pocket in front of jeans is for?

        Some people say "this is a kind of design style", some say "it is used to thicken the cloth to prevent the pocket from wearing out", and others say "this is the key for you..."

        The truth is

        This little pocket is a "watch bag"! Because at that time, the workers did not have watches and could only look at the time through pocket watches. In order to avoid scratches, workers often put it in the pocket of jeans. The pocket is small, so the pocket watch won't fall out easily. Although people rarely use pocket watches now, this pocket has been preserved. Now people will put lighters, coins and other small items in this pocket. Some people can even keep a small amount of private money!