WHY do mirrors change left to right, but not up to down?
The mirror is not aware of your position; it simply reflects the light that hits it. Then why, when the reflected light hits your eye's photoreceptors, does your image change from left to right?
Actually, the question of what makes the horizontal axis so special in the context of a mirror is itself incorrect. The fact is that the mirror does not reflect from left to right or top to bottom, but it does reflect backwards.
In other words, your mirror reflection is not reversed, but inverted into the third dimension, like a glove being turned inside out.
The mirror is not aware of your position; it simply reflects the light that hits it. Then why, when the reflected light hits your eye's photoreceptors, does your image change from left to right?
Actually, the question of what makes the horizontal axis so special in the context of a mirror is itself incorrect. The fact is that the mirror does not reflect from left to right or top to bottom, but it does reflect backwards.
In other words, your mirror reflection is not reversed, but inverted into the third dimension, like a glove being turned inside out.
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WHY does metal ring?
When deformed slightly, forces arise in the metal, tending to restore its original shape. However, these forces "bend the stick": the metal skips the equilibrium position and deforms in the opposite direction with acceleration. Then the elastic forces change direction, and everything repeats.
Sound vibrations arise, which pass from the metal to the air. The frequencies of the vibrations depend on the elastic properties of the material as well as the mass and shape of the object made of it. Predicting how a particular object will ring is not easy.
When deformed slightly, forces arise in the metal, tending to restore its original shape. However, these forces "bend the stick": the metal skips the equilibrium position and deforms in the opposite direction with acceleration. Then the elastic forces change direction, and everything repeats.
Sound vibrations arise, which pass from the metal to the air. The frequencies of the vibrations depend on the elastic properties of the material as well as the mass and shape of the object made of it. Predicting how a particular object will ring is not easy.
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WHY does hot metal glow?
When quanta of light move chaotically in space, physicists speak of a photon gas with a certain temperature. Every object tends to equalize its temperature with the surrounding photon gas: a cold object is heated by this gas, and a hot object gives energy to the gas in the form of radiation.
At room temperature, this radiation is invisible photons of the infrared range. But when heated to 400-500 °C, visible red light appears; at higher temperatures, yellow, white, and blue light emerges.
When quanta of light move chaotically in space, physicists speak of a photon gas with a certain temperature. Every object tends to equalize its temperature with the surrounding photon gas: a cold object is heated by this gas, and a hot object gives energy to the gas in the form of radiation.
At room temperature, this radiation is invisible photons of the infrared range. But when heated to 400-500 °C, visible red light appears; at higher temperatures, yellow, white, and blue light emerges.
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WHY does a drunk driver fog up his car windows?
Cause the dew point for water vapor rises if there is alcohol vapor in the air
The dew point is the temperature to which air containing a certain amount of water vapor must be cooled before the vapor begins to condense. The temperature of the glass is approximately the same as the outside temperature. If it is lower than the dew point for the cabin air, the windows will fog up.
Cause the dew point for water vapor rises if there is alcohol vapor in the air
The dew point is the temperature to which air containing a certain amount of water vapor must be cooled before the vapor begins to condense. The temperature of the glass is approximately the same as the outside temperature. If it is lower than the dew point for the cabin air, the windows will fog up.
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WHY do children move around a lot?
It helps them develop.
Movement is necessary for children primarily for the development of the nervous and musculoskeletal systems. With age, the capacity for volitional control and action planning becomes apparent, so the impulses that children express in movement are implemented in the mind of adults.
It helps them develop.
Movement is necessary for children primarily for the development of the nervous and musculoskeletal systems. With age, the capacity for volitional control and action planning becomes apparent, so the impulses that children express in movement are implemented in the mind of adults.
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WHY is a circle exactly 360 degrees?
In Sumer, and later in Babylon, the decimal number system was used. In this system, numbers from 1 to 59 were written in the decimal system, then counted in "sixties", then in 3600 (= 60²), and so on.
It was then that the circle began to be divided into six times 60 parts, which were later called degrees. But why not just into 60 parts? There are different versions. One explains this choice by the duration of the year (365,25 days), that is, the sun for a day is moved relative to the stars by about 1 °.
According to another version, this division is associated with a regular hexagon inscribed into a circle. Such a construction was found on a cuneiform tablet found in 1936. It was used to estimate the ratio of the length of the circle to its diameter.
In Sumer, and later in Babylon, the decimal number system was used. In this system, numbers from 1 to 59 were written in the decimal system, then counted in "sixties", then in 3600 (= 60²), and so on.
It was then that the circle began to be divided into six times 60 parts, which were later called degrees. But why not just into 60 parts? There are different versions. One explains this choice by the duration of the year (365,25 days), that is, the sun for a day is moved relative to the stars by about 1 °.
According to another version, this division is associated with a regular hexagon inscribed into a circle. Such a construction was found on a cuneiform tablet found in 1936. It was used to estimate the ratio of the length of the circle to its diameter.
WHY do goats wear beards?
Circumstantial evidence of this is the characteristic habit of goats to rub their beards with the secret of their under-tail glands (which are absent in females), which contain sex pheromones.
As zoologists assume, it is a "physiological calendar" that allows congeners to determine the age, condition and also to become an individual.
This feature plays an important role for contacts between members of the same species.
Circumstantial evidence of this is the characteristic habit of goats to rub their beards with the secret of their under-tail glands (which are absent in females), which contain sex pheromones.
As zoologists assume, it is a "physiological calendar" that allows congeners to determine the age, condition and also to become an individual.
This feature plays an important role for contacts between members of the same species.
WHY does gargling with salt water cure a sore throat?
Gargling with salt water is a common treatment for sore throats. According to otolaryngologists, gargling with a solution consisting of half a teaspoon of salt and a quarter cup of warm water relieves the pain caused by inflammation. Similarly, if soda is added to salt water, the solution can break down dense mucus.
The solution cleanses the mouth, temporarily washing away bacteria and pus.
Gargling with salt water is a common treatment for sore throats. According to otolaryngologists, gargling with a solution consisting of half a teaspoon of salt and a quarter cup of warm water relieves the pain caused by inflammation. Similarly, if soda is added to salt water, the solution can break down dense mucus.
The solution cleanses the mouth, temporarily washing away bacteria and pus.
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WHY does friction cause an object to heat up?
Object surfaces are not perfectly flat. Groups of atoms and molecules form a topography with protrusions and depressions. When the protrusions of two parts come close together, they can catch on each other mechanically or get bound by the forces of intermolecular attraction.
As a result, the atoms on the surface of the sliding parts first shift slightly from their equilibrium positions, and then, when the shift becomes too great, the bond between them is broken, and they, like on springs, return to their original position. In doing so, they gain speed and push neighboring atoms, causing them to move chaotically.
And the chaotic motion of the atoms is heat.
Object surfaces are not perfectly flat. Groups of atoms and molecules form a topography with protrusions and depressions. When the protrusions of two parts come close together, they can catch on each other mechanically or get bound by the forces of intermolecular attraction.
As a result, the atoms on the surface of the sliding parts first shift slightly from their equilibrium positions, and then, when the shift becomes too great, the bond between them is broken, and they, like on springs, return to their original position. In doing so, they gain speed and push neighboring atoms, causing them to move chaotically.
And the chaotic motion of the atoms is heat.
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WHY do light bulbs tend to explode when they burn out?
The filament of an incandescent bulb heats up to about 2000 °C. It oxidizes and degrades quite quickly in the air at this temperature. That is why the air is evacuated from the bulbs.
Yet if a small crack appears in the bulb through which air penetrates, it heats up sharply when the lamp is turned on and the increased pressure can destroy the bulb. Almost at the same moment the coil, which was in the air environment, burns out.
The filament of an incandescent bulb heats up to about 2000 °C. It oxidizes and degrades quite quickly in the air at this temperature. That is why the air is evacuated from the bulbs.
Yet if a small crack appears in the bulb through which air penetrates, it heats up sharply when the lamp is turned on and the increased pressure can destroy the bulb. Almost at the same moment the coil, which was in the air environment, burns out.
WHY can you see farther from a mountain in winter than in summer?
It's all about refraction - the curvature of the path of light as it moves through layers of air of varying density. This causes the light to twist slightly, allowing you to "look beyond the horizon”.
In summer, refraction at the horizon is about 0.5°, but in winter the cold air becomes denser and refraction increases, rarely reaching 2°. Then you can see more distant objects.
It's all about refraction - the curvature of the path of light as it moves through layers of air of varying density. This causes the light to twist slightly, allowing you to "look beyond the horizon”.
In summer, refraction at the horizon is about 0.5°, but in winter the cold air becomes denser and refraction increases, rarely reaching 2°. Then you can see more distant objects.
WHY do audiences in some theaters not applaud until the very end of Wagner's Parsifal?
The premiere of Wagner's Parsifal in Bayreuth was warmly received by the audience, but the composer, wishing to set the mood for serious applause, asked not to call the performers to their feet after each act, but only at the very end. The audience was confused and stopped even applauding, which confused Wagner himself. But it was too late - avoiding applause until the end of Parsifal had become a tradition in Bayreuth.
At one performance Wagner, seated in the auditorium himself, shouted: "Bravo!" to which he heard his neighbors hiss. In some theaters, such as the Metropolitan Opera, the audience supports this tradition; in others they applaud as usual.
The premiere of Wagner's Parsifal in Bayreuth was warmly received by the audience, but the composer, wishing to set the mood for serious applause, asked not to call the performers to their feet after each act, but only at the very end. The audience was confused and stopped even applauding, which confused Wagner himself. But it was too late - avoiding applause until the end of Parsifal had become a tradition in Bayreuth.
At one performance Wagner, seated in the auditorium himself, shouted: "Bravo!" to which he heard his neighbors hiss. In some theaters, such as the Metropolitan Opera, the audience supports this tradition; in others they applaud as usual.
WHY did cars used to be depicted in cartoons with oval wheels?
Early cameras didn't have fast central shutters, so they used shutters with moving shutters to take pictures of moving objects. This caused pictures of cars on the move to have oval wheels.
But this was not seen as a defect, as it was believed that such photos could not better emphasize the swiftness and speed. Later that is why artists of comics and cartoons often depicted cars with oval wheels.
Early cameras didn't have fast central shutters, so they used shutters with moving shutters to take pictures of moving objects. This caused pictures of cars on the move to have oval wheels.
But this was not seen as a defect, as it was believed that such photos could not better emphasize the swiftness and speed. Later that is why artists of comics and cartoons often depicted cars with oval wheels.
WHY does the expiration date on a bottle of drinking water refer to the bottle, not the water?
Drinking water itself has no expiration date - unlike the containers in which it is stored. When liquids are stored for long periods of time, plastic containers release chemicals that affect the taste and safety of the product. This does not mean that the water immediately becomes poisonous, but it gradually loses its freshness and can become stale.
It is believed that water in glass bottles retains its taste longer.
Drinking water itself has no expiration date - unlike the containers in which it is stored. When liquids are stored for long periods of time, plastic containers release chemicals that affect the taste and safety of the product. This does not mean that the water immediately becomes poisonous, but it gradually loses its freshness and can become stale.
It is believed that water in glass bottles retains its taste longer.
WHY do dried plants lose flavor and color, but retain their scent?
Many fruits retain their flavor and some of their color when dried, such as hot peppers. The insides of saffron blossoms are used as a food coloring because of their resistance to drying. But in general, the smell is really more persistent than the taste and color.
The reason for this is that the aroma of plants is determined by the presence of essential oils, esters and higher alcohols, which are chemically stable even in the absence of moisture. And color and taste depend on substances that are usually stable only in aqueous solutions. When they dry out, they break down or combine with other substances, losing their properties.
Many fruits retain their flavor and some of their color when dried, such as hot peppers. The insides of saffron blossoms are used as a food coloring because of their resistance to drying. But in general, the smell is really more persistent than the taste and color.
The reason for this is that the aroma of plants is determined by the presence of essential oils, esters and higher alcohols, which are chemically stable even in the absence of moisture. And color and taste depend on substances that are usually stable only in aqueous solutions. When they dry out, they break down or combine with other substances, losing their properties.
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WHY are there freshwater icebergs in the salty ocean?
Since the glaciers of Greenland and Antarctica.
When the salty ocean water evaporates, it turns fresh and falls as precipitation. In Greenland and Antarctica, the fallen snow compacts under its own weight and slides off the edges of the land. A so-called ice shelf glacier is formed, and huge pieces of icebergs break away from the edges of the glacier.
Since the glaciers of Greenland and Antarctica.
When the salty ocean water evaporates, it turns fresh and falls as precipitation. In Greenland and Antarctica, the fallen snow compacts under its own weight and slides off the edges of the land. A so-called ice shelf glacier is formed, and huge pieces of icebergs break away from the edges of the glacier.
WHY are the lights dimmed on board during take-off?
The flight crew turns off the main cabin lights during take-off and landing for the safety of the passengers in case of an emergency.
It is done so that passengers' eyes become accustomed to the dark, not for comfort but for safety reasons.
If passengers need to be evacuated immediately, their eyes will be better prepared for darkness or smoke. In addition, emergency signs will be more visible.
The flight crew turns off the main cabin lights during take-off and landing for the safety of the passengers in case of an emergency.
It is done so that passengers' eyes become accustomed to the dark, not for comfort but for safety reasons.
If passengers need to be evacuated immediately, their eyes will be better prepared for darkness or smoke. In addition, emergency signs will be more visible.
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Why don't people wake up from their own snoring?
Since even in sleep the brain analyzes sounds, and the sleeper wakes up if the sound is unexpected or has a signal meaning (call, name calling). A person may also be awakened by the absence of a sound, for example, if a night train, which constantly passes by his house at the same time, for some reason did not pass by.
At the same time, the loud but familiar noise does not bother the person, which is known to anyone who has fallen asleep in the subway. Here, too, the snorer's brain does not perceive snoring as an unexpected sound.
Since even in sleep the brain analyzes sounds, and the sleeper wakes up if the sound is unexpected or has a signal meaning (call, name calling). A person may also be awakened by the absence of a sound, for example, if a night train, which constantly passes by his house at the same time, for some reason did not pass by.
At the same time, the loud but familiar noise does not bother the person, which is known to anyone who has fallen asleep in the subway. Here, too, the snorer's brain does not perceive snoring as an unexpected sound.
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WHY does the sloth's fur turn green?
The sloth got its name because of its sedentary, half-sleeping lifestyle. The animal has poorly developed hearing, but this drawback is largely compensated by its sense of smell and sight, as well as the presence of two extra vertebrae, which allow it to turn its head by 270°.
The sloth's long, shaggy, often piled fur grows toward its belly, and in its "grooves" live and multiply two kinds of algae, which give the animal a greenish-brown color.
This "camouflage suit" allows the animal to live relatively quietly, remaining unnoticed in the jungle among numerous predators.
The sloth got its name because of its sedentary, half-sleeping lifestyle. The animal has poorly developed hearing, but this drawback is largely compensated by its sense of smell and sight, as well as the presence of two extra vertebrae, which allow it to turn its head by 270°.
The sloth's long, shaggy, often piled fur grows toward its belly, and in its "grooves" live and multiply two kinds of algae, which give the animal a greenish-brown color.
This "camouflage suit" allows the animal to live relatively quietly, remaining unnoticed in the jungle among numerous predators.
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WHY are Dalmatians "carriage dogs"?
In Great Britain, the Dalmatian became known as a carriage dog. Their carriage escort, strength, endurance and fearlessness made them the constant companions of the English nobility. The dogs ran under the front axle of the carriage and could travel long distances on a par with horses.
During the halts the faithful animals, caressing and entertaining their masters, did not forget to vigilantly guard their peace. At the slightest danger, they bravely fought both wild animals and forest robbers.
This is why "carriage" dogs had their floppy ears cropped, which suffered most during fights. The first official "Dalmatian Club" was established by the British in 1890 and they also developed a show standard for this breed.
In Great Britain, the Dalmatian became known as a carriage dog. Their carriage escort, strength, endurance and fearlessness made them the constant companions of the English nobility. The dogs ran under the front axle of the carriage and could travel long distances on a par with horses.
During the halts the faithful animals, caressing and entertaining their masters, did not forget to vigilantly guard their peace. At the slightest danger, they bravely fought both wild animals and forest robbers.
This is why "carriage" dogs had their floppy ears cropped, which suffered most during fights. The first official "Dalmatian Club" was established by the British in 1890 and they also developed a show standard for this breed.
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