WHY is the explosion of a grenade in water hazier than on land?
In the air, a person is struck by flying grenade fragments. Under water, they quickly decelerate and water pressure serves as the main striking factor. The water set in motion by the explosion presses on the human body. Upon reaching the organs containing air, the pressure sharply squeezes and unclenches them, tearing the tissues.
Death threatens the person at a distance of 6-7 meters from the explosion, and the obstacles are almost beyond saving.
In the air, a person is struck by flying grenade fragments. Under water, they quickly decelerate and water pressure serves as the main striking factor. The water set in motion by the explosion presses on the human body. Upon reaching the organs containing air, the pressure sharply squeezes and unclenches them, tearing the tissues.
Death threatens the person at a distance of 6-7 meters from the explosion, and the obstacles are almost beyond saving.
👍6
WHY do lint appear?
Lint is the loose fibers or balls of fabric that form on the surface of the material. The reason for their appearance is friction on the surface of the fabric or abrasion from rougher surfaces. Coils on clothing are considered unaesthetic.
The most frequent reason for the formation of lint on clothing is due to improper care of the clothing. Daily wear, washing and drying at inappropriate temperatures have an adverse effect on the fabric, resulting in the formation of lint.
Items made of polyamide (nylon), capron, lavsan (polyester and polyamide fibers) are particularly prone to the formation of lint. Among synthetic fabrics, acrylic is less prone to lint.
Lint is the loose fibers or balls of fabric that form on the surface of the material. The reason for their appearance is friction on the surface of the fabric or abrasion from rougher surfaces. Coils on clothing are considered unaesthetic.
The most frequent reason for the formation of lint on clothing is due to improper care of the clothing. Daily wear, washing and drying at inappropriate temperatures have an adverse effect on the fabric, resulting in the formation of lint.
Items made of polyamide (nylon), capron, lavsan (polyester and polyamide fibers) are particularly prone to the formation of lint. Among synthetic fabrics, acrylic is less prone to lint.
WHY do trees need bark?
The bark protects the tree throughout its life.
The top coarse layer of bark protects the tree from drying out or freezing and keeps pests out, so it is essential to the tree. The bark is formed with a layer called cambium, located between the wood and the bark.
Throughout a tree's life, a thin layer of cambium forms new ones of bark and wood (bark on the outside, wood on the inside). Thanks to this coordinated work of the cambium, the tree grows upward and outward. The inner layer of bark is responsible for the movement of nutrients from the crown down to the flowers, fruits and roots.
Damage to the bark can kill a healthy tree as it then loses its protection from pests, cold and heat.
The bark protects the tree throughout its life.
The top coarse layer of bark protects the tree from drying out or freezing and keeps pests out, so it is essential to the tree. The bark is formed with a layer called cambium, located between the wood and the bark.
Throughout a tree's life, a thin layer of cambium forms new ones of bark and wood (bark on the outside, wood on the inside). Thanks to this coordinated work of the cambium, the tree grows upward and outward. The inner layer of bark is responsible for the movement of nutrients from the crown down to the flowers, fruits and roots.
Damage to the bark can kill a healthy tree as it then loses its protection from pests, cold and heat.
👍3🔥1
WHY does the skin renew itself but the tattoos stay?
The top layer of skin, the epidermis, is refreshed every couple of weeks. Its lower layers divide to form keratinocytes, which then peel off and new ones grow underneath.
The dye that has penetrated the epidermis exfoliates along with the dying cells. However, below lies the dermis layer, which gets renewed extremely slowly. In addition, the space between its cells is filled with a network of collagen fibers — durable and chemically almost inert.
The pigment particles in the dermis stay there forever.
The top layer of skin, the epidermis, is refreshed every couple of weeks. Its lower layers divide to form keratinocytes, which then peel off and new ones grow underneath.
The dye that has penetrated the epidermis exfoliates along with the dying cells. However, below lies the dermis layer, which gets renewed extremely slowly. In addition, the space between its cells is filled with a network of collagen fibers — durable and chemically almost inert.
The pigment particles in the dermis stay there forever.
😱5👍2
WHY can electronic clocks lag?
The "heart" of an electronic clock is a frequency oscillator with a crystal quartz plate fluctuating in it. It is adjusted so that the clock runs exactly at room temperature (about 25 °C).
As the temperature deviates from this point, the oscillation frequency decreases and the watch lags (up to a few minutes per year). The more expensive models use a temperature-compensated quartz, with which the error does not exceed a few seconds per year.
The "heart" of an electronic clock is a frequency oscillator with a crystal quartz plate fluctuating in it. It is adjusted so that the clock runs exactly at room temperature (about 25 °C).
As the temperature deviates from this point, the oscillation frequency decreases and the watch lags (up to a few minutes per year). The more expensive models use a temperature-compensated quartz, with which the error does not exceed a few seconds per year.
👍1😱1
WHY is the intestines called the second brain?
The intestines and the brain exchange signals through the vagus nerve, running down the neck to the thoracic and abdominal cavity. Giulia Enders, bestselling author of "The Charming Gut. How the Most Powerful Authority Controls Us," compares the vagus nerve to the telephone wire linking the intestines to the individual centers of the brain.
The brain directs all the organs of the body, and many via the vagus nerve, but only the intestines have autonomy: if the nerve is cut, "disconnecting" the brain from the intestines, the latter will keep working.
It possesses its own nervous system, which scientists call the "second brain". It consists of a huge number of neurons and auxiliary cells, produces several dozens of neurotransmitters.
The intestines and the brain exchange signals through the vagus nerve, running down the neck to the thoracic and abdominal cavity. Giulia Enders, bestselling author of "The Charming Gut. How the Most Powerful Authority Controls Us," compares the vagus nerve to the telephone wire linking the intestines to the individual centers of the brain.
The brain directs all the organs of the body, and many via the vagus nerve, but only the intestines have autonomy: if the nerve is cut, "disconnecting" the brain from the intestines, the latter will keep working.
It possesses its own nervous system, which scientists call the "second brain". It consists of a huge number of neurons and auxiliary cells, produces several dozens of neurotransmitters.
👍6🔥1
WHY doesn't the bottom button of a jacket get buttoned?
This etiquette has been observed since the beginning of the XX century. Historians assume that the rule of wearing a jacket appeared thanks to the English King Edward VII (1841-1910), who was obese. He used to leave the bottom button undone so that a tight vest would fit better.
As a sign of respect for his king, the British court, and after him all the inhabitants of England and the British colonies, no longer buttoned the bottom vest. This theory is not taken seriously by everyone, and some trendsetters have challenged it with other versions.
Fashion designer Hardy Amies explained the single-breasted suit was first introduced in 1906 and was later called the "leisure suit".
It became a casual garment, had a wide cut, and the three buttons gave the suit a proper fit. Over time, the jacket replaced traditional riding coats. And as the third button was below the waist, it was unbuttoned while sitting on a horse for comfort.
This etiquette has been observed since the beginning of the XX century. Historians assume that the rule of wearing a jacket appeared thanks to the English King Edward VII (1841-1910), who was obese. He used to leave the bottom button undone so that a tight vest would fit better.
As a sign of respect for his king, the British court, and after him all the inhabitants of England and the British colonies, no longer buttoned the bottom vest. This theory is not taken seriously by everyone, and some trendsetters have challenged it with other versions.
Fashion designer Hardy Amies explained the single-breasted suit was first introduced in 1906 and was later called the "leisure suit".
It became a casual garment, had a wide cut, and the three buttons gave the suit a proper fit. Over time, the jacket replaced traditional riding coats. And as the third button was below the waist, it was unbuttoned while sitting on a horse for comfort.
WHY does jetlag emerge?
Jetlag is a disruption of the daily biological rhythms of the body due to the change of time zones. According to the practice of experienced travelers, a flight from west to east is worse than a flight from east to west.
The main cause of Jetlag is the inability of the human body to adjust to the time in another zone as soon as it lands. Our biological clock has a certain mode that begins to conflict with the new routine, especially day/night light.
The biological clock is responsible not only for sleeping and waking times, but also for meal times, body temperature, hormone regulation and other body functions. For this reason, the body gets "uncomfortable" after a long flight.
Jetlag is a disruption of the daily biological rhythms of the body due to the change of time zones. According to the practice of experienced travelers, a flight from west to east is worse than a flight from east to west.
The main cause of Jetlag is the inability of the human body to adjust to the time in another zone as soon as it lands. Our biological clock has a certain mode that begins to conflict with the new routine, especially day/night light.
The biological clock is responsible not only for sleeping and waking times, but also for meal times, body temperature, hormone regulation and other body functions. For this reason, the body gets "uncomfortable" after a long flight.
👍4😁2
WHY shouldn't boiled water be used in an aquarium?
Boiling reduces the hardness of the water, eliminating oxygen and killing beneficial microorganisms.
Boiling makes the water "dead". If you immediately pour water into the aquarium, which boiled, you had time to cool it, most likely the fish will feel sick. The reason for this is that such a liquid lacks oxygen, so if the filter does not function well, it will take some time to saturate it with the vital element.
Boiling reduces the hardness of the water, eliminating oxygen and killing beneficial microorganisms.
Boiling makes the water "dead". If you immediately pour water into the aquarium, which boiled, you had time to cool it, most likely the fish will feel sick. The reason for this is that such a liquid lacks oxygen, so if the filter does not function well, it will take some time to saturate it with the vital element.
👍4🔥2
WHY shouldn't everything in pain be heated?
Under the influence of heat, the walls of blood vessels expand and their permeability increases, resulting in an increased inflow of blood and blood flow. This causes germs and products of their metabolism to move beyond the original focus.
⠀
True, the pain passes, but only due to the fact that the substances are not concentrated in one place, but migrate throughout the bloodstream. It is likely they will settle in another organ.
Under the influence of heat, the walls of blood vessels expand and their permeability increases, resulting in an increased inflow of blood and blood flow. This causes germs and products of their metabolism to move beyond the original focus.
⠀
True, the pain passes, but only due to the fact that the substances are not concentrated in one place, but migrate throughout the bloodstream. It is likely they will settle in another organ.
😱6👍4
WHY shouldn't we use the phone before going to bed?
Experts suggest that the main reason why it's hard to fall asleep after using your phone is that you don't have time to settle down. Lots of people play right in bed, some read the news, others flip through their social media feeds. All of these activities can excite you both mentally and physically.
Curiously, many of these actions cause your body to produce cortisol, the stress hormone. Such as if you've read the disturbing news, or if an online game has a monster chasing you. Cortisol doesn't let you sleep, on the contrary, it wakes you up, since you can't sleep under conditions of "anxiety and danger"!
Experts suggest that the main reason why it's hard to fall asleep after using your phone is that you don't have time to settle down. Lots of people play right in bed, some read the news, others flip through their social media feeds. All of these activities can excite you both mentally and physically.
Curiously, many of these actions cause your body to produce cortisol, the stress hormone. Such as if you've read the disturbing news, or if an online game has a monster chasing you. Cortisol doesn't let you sleep, on the contrary, it wakes you up, since you can't sleep under conditions of "anxiety and danger"!
🔥1
WHY do insects survive falls from great heights?
It turns out that it's about the shape of the bugs body and air resistance.
Under the first factor is the surface area of the insect's body. As you know, with increasing area, the frontal resistance of the body to the flow of air also grows. When the body falls, gravity acts on it, which is determined by the mass and acceleration of free fall.
The mass of insects, as a rule, is several tens of grams, so the gravity acting on their body is quite small. In this case, the frontal resistance to air flow is significant, due to which the resultant force, which determines the acceleration with which it moves, is relatively small.
It turns out that it's about the shape of the bugs body and air resistance.
Under the first factor is the surface area of the insect's body. As you know, with increasing area, the frontal resistance of the body to the flow of air also grows. When the body falls, gravity acts on it, which is determined by the mass and acceleration of free fall.
The mass of insects, as a rule, is several tens of grams, so the gravity acting on their body is quite small. In this case, the frontal resistance to air flow is significant, due to which the resultant force, which determines the acceleration with which it moves, is relatively small.
👍4🔥1
WHY is the gas tank on the left side of some cars and the right side of others?
In European automakers, the gas tank is mostly located on the right side of left-hand drive cars. So the driver doesn't have to worry about the door hitting the gas tank, and it takes longer for fuel vapors to enter the cabin through the open driver's door.
Some Asian brands ship left-handed cars to foreign markets with left-handed throats. This is most likely due to the fact that an additional change in design will increase the cost of manufacturing the car, and the position of the neck, by and large, is not that big of a deal.
In European automakers, the gas tank is mostly located on the right side of left-hand drive cars. So the driver doesn't have to worry about the door hitting the gas tank, and it takes longer for fuel vapors to enter the cabin through the open driver's door.
Some Asian brands ship left-handed cars to foreign markets with left-handed throats. This is most likely due to the fact that an additional change in design will increase the cost of manufacturing the car, and the position of the neck, by and large, is not that big of a deal.
👍6
WHY is walking in a coniferous forest healthy?
Scientists have proven that the air in a coniferous forest is practically sterile (no more than 200-300 harmful bacteria per cubic meter). A walk in the coniferous forest relieves stress and nervous tension, tones the body by activating gas exchange in the lungs and, consequently, improves breathing.
Such walks are vital for heavy smokers and office workers.
Scientists have proven that the air in a coniferous forest is practically sterile (no more than 200-300 harmful bacteria per cubic meter). A walk in the coniferous forest relieves stress and nervous tension, tones the body by activating gas exchange in the lungs and, consequently, improves breathing.
Such walks are vital for heavy smokers and office workers.
👍4😁2
WHY do ancient sculptures appear with "empty" eyes?
Previously, it was thought that ancient sculpture had come down to us in its original form. Yet later it was revealed that ancient Greek sculptors did not leave the eyes of their statues lifeless and the marble creations themselves were not white and cold, they were painted.
Acropolis bark (statues of girls) were found in the 19th century, preserving the paint: dark hair, red lips and multi-colored eyes.
Later traces of the coloring were found on other ancient sculptures as well. A few years ago German scholars attempted to reconstruct the original appearance of 12 ancient marble sculptures. The result is an exhibition with the cleverly titled "The motley gods". The bronze Greek sculptures had not painted, but inlaid eyes.
Previously, it was thought that ancient sculpture had come down to us in its original form. Yet later it was revealed that ancient Greek sculptors did not leave the eyes of their statues lifeless and the marble creations themselves were not white and cold, they were painted.
Acropolis bark (statues of girls) were found in the 19th century, preserving the paint: dark hair, red lips and multi-colored eyes.
Later traces of the coloring were found on other ancient sculptures as well. A few years ago German scholars attempted to reconstruct the original appearance of 12 ancient marble sculptures. The result is an exhibition with the cleverly titled "The motley gods". The bronze Greek sculptures had not painted, but inlaid eyes.
👍2
WHY do the batteries in a flashlight run out on their own?
The same law applies everywhere, that the accumulated charge cannot last forever, and as a consequence, batteries and accumulators have an expiration date not only when they are lying on the shelf in the store, but also when they are inserted into some device which may be a consumer.
Frequently, the current consumption is so low that the components of the circuitry warm up only slightly. However, this consumes the battery, and as a consequence, one gets a dead battery sooner than one expects.
Conductors run from the contacts of the battery to the flashlight switch. Even if the circuit is open, the distance between the switch contacts is about a millimeter. A weak current can flow through this gap and discharge the batteries.
The same law applies everywhere, that the accumulated charge cannot last forever, and as a consequence, batteries and accumulators have an expiration date not only when they are lying on the shelf in the store, but also when they are inserted into some device which may be a consumer.
Frequently, the current consumption is so low that the components of the circuitry warm up only slightly. However, this consumes the battery, and as a consequence, one gets a dead battery sooner than one expects.
Conductors run from the contacts of the battery to the flashlight switch. Even if the circuit is open, the distance between the switch contacts is about a millimeter. A weak current can flow through this gap and discharge the batteries.
👍1
WHY can sound be heard at a great distance on a rainy day?
There is a state of sound refraction caused by temperature inversion. When the ground and air near the ground is colder than the air above, sound travels faster at altitude than it does over the ground.
A sound wave, angled upward relative to the earth's surface, is gradually deflected backward so that it hits the ground a mile or more from where it began. On a rainy day, rain cools the ground, but the air above the clouds remains warm.
The temperature inversion effect was the bane of outdoor rock concerts. They needed a roof to stop the celestial wave. No amount of walls would help.
There is a state of sound refraction caused by temperature inversion. When the ground and air near the ground is colder than the air above, sound travels faster at altitude than it does over the ground.
A sound wave, angled upward relative to the earth's surface, is gradually deflected backward so that it hits the ground a mile or more from where it began. On a rainy day, rain cools the ground, but the air above the clouds remains warm.
The temperature inversion effect was the bane of outdoor rock concerts. They needed a roof to stop the celestial wave. No amount of walls would help.
WHY does snow glisten in the sun?
Snowflakes are ice crystals with many flat facets which act as microscopic mirrors. Those that reflect sunlight directly into the eye give a bright point. And if you move a little bit, the rays of other snowflakes hit your eye.
Therefore, when you keep moving, the shiny dots alternate with each other. Freshly fallen snow is shinier than lain snow, as flat edges of snowflakes are scratched, broken, and melted with time.
Snowflakes are ice crystals with many flat facets which act as microscopic mirrors. Those that reflect sunlight directly into the eye give a bright point. And if you move a little bit, the rays of other snowflakes hit your eye.
Therefore, when you keep moving, the shiny dots alternate with each other. Freshly fallen snow is shinier than lain snow, as flat edges of snowflakes are scratched, broken, and melted with time.
🤩1
WHY can sound be heard at a great distance on a rainy day?
There is a state of sound refraction caused by temperature inversion. When the ground and air near the ground is colder than the air above, sound travels faster at altitude than it does over the ground.
A sound wave, angled upward relative to the earth's surface, is gradually deflected backward so that it hits the ground a mile or more from where it began. On a rainy day, rain cools the ground, but the air above the clouds remains warm.
The temperature inversion effect was the bane of outdoor rock concerts. They needed a roof to stop the celestial wave. No amount of walls would help.
There is a state of sound refraction caused by temperature inversion. When the ground and air near the ground is colder than the air above, sound travels faster at altitude than it does over the ground.
A sound wave, angled upward relative to the earth's surface, is gradually deflected backward so that it hits the ground a mile or more from where it began. On a rainy day, rain cools the ground, but the air above the clouds remains warm.
The temperature inversion effect was the bane of outdoor rock concerts. They needed a roof to stop the celestial wave. No amount of walls would help.
😱1
WHY shouldn't trash be burned in volcanoes?
⠀
The reason is that dumping trash into the lava lakes of volcanoes can trigger an eruption. Lava lakes are volatile, so if you pierce their surfaces with something cold, like garbage, you cause a chain reaction of explosions with compressed and acidic vapor.
⠀
Also, all the moisture accumulated in the debris instantly evaporates, the steam expands, comes out, rips the debris and creates bursts of molten rock.
⠀
The reason is that dumping trash into the lava lakes of volcanoes can trigger an eruption. Lava lakes are volatile, so if you pierce their surfaces with something cold, like garbage, you cause a chain reaction of explosions with compressed and acidic vapor.
⠀
Also, all the moisture accumulated in the debris instantly evaporates, the steam expands, comes out, rips the debris and creates bursts of molten rock.
🔥3