Why breathe before throwing a paper plane?
There are different opinions about this childhood mystery. Someone tried to explain from a physical point of view: the moisture produced by the breath can add weight to the aircraft head, thereby making the fuselage more stable during flight. Think about badminton and the heavier head. Some people think that the breath can increase the temperature of the aircraft head and play a preheating role, so that when it rubs against the air, it can reduce energy loss. Some people think of the wind tunnel experiment of the aircraft, and think that the breath is simulating the effect of the airflow on the aircraft to test whether the paper aircraft can operate normally.
Sun Cong, an academician of the Chinese Academy of Engineering and the chief designer of the J-15 carrier-based aircraft, believes that this is just a “lucky picture.” The general secretary of the International Paper Aircraft Association also expressed the same view: the breath has no effect on the paper plane’s stagnation time.
Why are kiwis covered with hair?
The fluff on the kiwi skin is to protect the flesh inside. The small black seeds in the flesh are the seeds, which need to be protected. The seeds need to stay in the juicy pulp until they are mature. If the pulp is eaten by insects, the seeds will not grow properly.
Kiwi’s skin is actually edible and nutritious, but most people don’t like the mouthfeel. Not all kiwis are fluffy. Some types of kiwis are particularly small, so they are strawberry-like in size, and their skins have no hair.
Why do fireflies glow?
Fireflies glow because they have light emitters at the ends of their abdomen. The substance that makes fireflies glow is called luciferase. The light emitted by fireflies is called cold light because most of the energy is converted into light energy, and only a small part is converted into heat energy. Luminescence has the purposes of courtship, vigilance, and trapping.
This is also a communication tool for them. Different types of fireflies have different lighting methods, lighting frequencies and colors, and they use this to convey different messages.
Does tooth extraction really reduce face?
In fact, tooth extraction can’t thin the face, and the effect of tooth extraction on the shape of adults’ faces is also very small, because it is the jaw angle that supports our facial contours, and the wisdom teeth are inside the mouth, far away from the jaw angle. Because children are still developing, it is only during this period that the wisdom teeth are extracted to have a certain effect on the face shape. Adults’ face shape changes are usually done by mandibular angle plastic surgery, or by grinding the mandibular margin.
In fact, there are many better ways to improve facial health, such as whole teeth. Many people think that they have the problem of big and small faces. Generally, the muscle development is asymmetric due to one-sided chewing. If the muscle problem is changed to two-sided chewing, it can be solved. Some people are caused by asymmetric bone development. In this case, exercise cannot solve the problem, and surgery must be performed.
Why is the chef’s hat so high?
There are many versions of the origin of the chef hat, one of the most widely circulated claims dates back to the 7th century AD. At that time, Greece was invaded, and the Greek chefs were also persecuted. They sought refuge from the Greek Orthodox Church. In order to mix with the clergy, the chefs put on the same clothes as the clergy, including a Cameronian hat similar to a top hat. After the war, the chefs did not take off their hats, but kept it. It is said to commemorate this period of tribulation, as a symbol of unity. Later, this hat was gradually transformed into what it is now.
In the early 19th century, the height of the chef’s hat was hooked to the level of the chef. The higher the chef hat, the higher the chef’s skill level. A chef once wore a chef hat with a height of nearly half a meter to highlight his central position in the kitchen. Today’s chef hats are generally 23 to 30 centimeters high, and the relationship between the height and the chef’s level has also faded, but only the chef or a high-level chef is still qualified to wear a tall chef hat.
Why did the ancients meet “to fight”?
Zuoyi is a traditional etiquette of ancient Chinese Han people. “Zuo Yi Li” and “Gong Shou Li” are different. “Zhou Shou Li” is a common etiquette for greeting among civilians, and “Zuo Yi Li” is a common etiquette when gentry meets or thanks. When you press, the four fingers except the thumb are together, the left and right palms are flat, the palm is inward, the thumb is buckled, and the two hands are pushed forward together. Compared with Gongshou Li and Gongquan Li, Zuo Yi is more formal and more solemn. When the ancients meet, especially when they are visiting guests at home, before entering the door and sitting down, the host and the guest should salute each other to express humility.
However, it should be noted that male and female gestures are opposite. The male wraps his left hand outside his right hand, while the female wraps his right hand outside his left. Later, there was a Wanfu ceremony exclusively for women. During the ceremony, hands were folded in front of the lower abdomen, and the right hand was placed outside the left hand.
Is there liquid in the LCD screen?
There is indeed a special fluid in the LCD screen, called liquid crystal. As its name implies, liquid crystals have some properties of liquids and crystals: on the one hand, they can flow like liquids; on the other hand, the arrangement of molecules in them is as orderly as solid crystals, which can be said to be between liquid and solid State. By applying different voltages to the liquid crystal layer in the screen, you can change the arrangement of its molecules and display different optical characteristics, such as light transmittance. This photoelectric effect is the basic principle of liquid crystal screen imaging.
There are many types of liquid crystal, and common ones include biphenyl liquid crystal, phenylcyclohexane liquid crystal and ester liquid crystal. Traditional display screens such as CRT picture tube displays (electron beams excite phosphors on the inner surface of the screen to display images) tend to be large, while LCD screens can be very thin and light, and require low voltage and low power consumption, so they are more affected by Favored