WHY are sewer manholes round?
The greater ratio of the cross-sectional area of the round manhole hole to the length of the circumference of its body than in a square or rectangular. As a result, you can reduce the cost of production by reducing the consumption of materials without compromising performance.
Round shape allows you to ensure that the cover itself will not fall through the hatch during its assembly or disassembly. In principle, this problem can be solved by using a hatch, repeating the shape of any curve of constant width, but the circle of all possible such figures is the most technologically advanced.
The greater ratio of the cross-sectional area of the round manhole hole to the length of the circumference of its body than in a square or rectangular. As a result, you can reduce the cost of production by reducing the consumption of materials without compromising performance.
Round shape allows you to ensure that the cover itself will not fall through the hatch during its assembly or disassembly. In principle, this problem can be solved by using a hatch, repeating the shape of any curve of constant width, but the circle of all possible such figures is the most technologically advanced.
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WHY do crab sticks have nothing to do with crabs?
The recipe for this snack originated in 1973 in Japan and hasn't changed much since then. The need for crab sticks was born out of the fact that at some point the number of crabs, a terribly essential attribute of Japanese cuisine, began to dwindle rapidly.
Ingenious Japanese came up with a replacement. They took as the basis a dish called "Kamaboko" - for its cooking cod fish fillets are used - it is pure white color. These fish fillets are crushed, then ground, and in this way they obtain surimi meat. Potatoes, soy sauce, starch, egg powder and flavorings are added. Then the resulting mass is made into oblong sticks and evaporated to get rid of the fat.
Completing the process is the application of food coloring red or orange.
The recipe for this snack originated in 1973 in Japan and hasn't changed much since then. The need for crab sticks was born out of the fact that at some point the number of crabs, a terribly essential attribute of Japanese cuisine, began to dwindle rapidly.
Ingenious Japanese came up with a replacement. They took as the basis a dish called "Kamaboko" - for its cooking cod fish fillets are used - it is pure white color. These fish fillets are crushed, then ground, and in this way they obtain surimi meat. Potatoes, soy sauce, starch, egg powder and flavorings are added. Then the resulting mass is made into oblong sticks and evaporated to get rid of the fat.
Completing the process is the application of food coloring red or orange.
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WHY is it so hard to win from a toy machine?
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Anyone who has tried to get a toy out of a grabber knows that it's much harder than it appears. Vox explains that it's not the skill of the players, but the machines themselves, which are set up to cheat.
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The edition has studied the manual to one of these machines and found that the "paw" of the manipulator is programmed to only sometimes squeeze the toys with full force. The owner can set the probability of the paw squeezing the toy hard enough and when it only grabs it a little.
The machine also has a "reset" parameter - the owner can set how frequently the "paw" will drop a toy that has already been grabbed.
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Anyone who has tried to get a toy out of a grabber knows that it's much harder than it appears. Vox explains that it's not the skill of the players, but the machines themselves, which are set up to cheat.
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The edition has studied the manual to one of these machines and found that the "paw" of the manipulator is programmed to only sometimes squeeze the toys with full force. The owner can set the probability of the paw squeezing the toy hard enough and when it only grabs it a little.
The machine also has a "reset" parameter - the owner can set how frequently the "paw" will drop a toy that has already been grabbed.
WHY do Japan lack old houses?
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In this country, it is believed that a house loses value from the first day it is built. In 10 years, the value of a house is halved. After 25 years it is considered far too old to live in and worthless. After that, it is demolished and a new house is built in its place. Even landmarks and major shrines are regularly rebuilt.
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So Japanese people have no examples of old architecture; all the houses are modern. This has a negative effect on the appearance of Japanese cities: the architecture in them is quite monotonous and rarely decorated in any way.
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In this country, it is believed that a house loses value from the first day it is built. In 10 years, the value of a house is halved. After 25 years it is considered far too old to live in and worthless. After that, it is demolished and a new house is built in its place. Even landmarks and major shrines are regularly rebuilt.
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So Japanese people have no examples of old architecture; all the houses are modern. This has a negative effect on the appearance of Japanese cities: the architecture in them is quite monotonous and rarely decorated in any way.
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WHY does the Guinness World Records no longer list the world's fattest animals?
The Guinness World Records contains a myriad of incredible entries: the world's tallest man, the world's shortest rivers, the heaviest tumor... However, several things cannot appear in the book.
Like, no more records related to diet and alcohol consumption are accepted: perhaps because the "Book" doesn't want to get sued for doing something stupid and thereby harming itself.
The Guinness World Records once listed the world's fattest fish, and after that, some fish owners started giving their pets too much food in an attempt to break the record - exactly the kind of behavior the Guinness World Records managers would like to avoid.
The Guinness World Records contains a myriad of incredible entries: the world's tallest man, the world's shortest rivers, the heaviest tumor... However, several things cannot appear in the book.
Like, no more records related to diet and alcohol consumption are accepted: perhaps because the "Book" doesn't want to get sued for doing something stupid and thereby harming itself.
The Guinness World Records once listed the world's fattest fish, and after that, some fish owners started giving their pets too much food in an attempt to break the record - exactly the kind of behavior the Guinness World Records managers would like to avoid.
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WHY do many crabs appear to have one claw larger than the other?
The larger claw, with its powerful teeth, is designed for crushing shells of mollusks and shells of sea urchins, the prey of the crabs. The second claw is fitted with an edge for cutting soft tissues or bristles serving as a filtration apparatus.
In males of half land beckoning crabs, one huge claw has turned into a "tournament weapon": it is used for mating demonstrations and in fights between males.
The larger claw, with its powerful teeth, is designed for crushing shells of mollusks and shells of sea urchins, the prey of the crabs. The second claw is fitted with an edge for cutting soft tissues or bristles serving as a filtration apparatus.
In males of half land beckoning crabs, one huge claw has turned into a "tournament weapon": it is used for mating demonstrations and in fights between males.
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WHY do cooking smells spread throughout the house?
Due to the heated air. All odors sooner or later spread throughout the entire space available to them. However, cooking smells tend to have an amplified effect. The thing is, the stove heats the air above it as it cooks.
By rising, it forms currents carrying odorous substances from cooking and roasting foods around the room.
Due to the heated air. All odors sooner or later spread throughout the entire space available to them. However, cooking smells tend to have an amplified effect. The thing is, the stove heats the air above it as it cooks.
By rising, it forms currents carrying odorous substances from cooking and roasting foods around the room.
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WHY does a fly hit the glass when a section of window is open nearby?
A fly exhibits mosaic vision, and its eyes consist of a large number of facets. A fly may have as many as 8,000 of them. Each facet can be viewed as a tiny eyeball. It consists of a lens and a crystal.
The point is that the fly is unable to discern whether or not there is a glass in front of it. It is due to low visual acuity. Therefore, the insect simply tries to fly forward in the hope of luck. And a side-by-side open window doesn't make it any easier for it to enter the street, as the fly has no idea whether it can fly out there without any problems.
In contrast, if you take the insect in your hand and let it go in front of the open bid, it will fly out immediately, without hesitation.
A fly exhibits mosaic vision, and its eyes consist of a large number of facets. A fly may have as many as 8,000 of them. Each facet can be viewed as a tiny eyeball. It consists of a lens and a crystal.
The point is that the fly is unable to discern whether or not there is a glass in front of it. It is due to low visual acuity. Therefore, the insect simply tries to fly forward in the hope of luck. And a side-by-side open window doesn't make it any easier for it to enter the street, as the fly has no idea whether it can fly out there without any problems.
In contrast, if you take the insect in your hand and let it go in front of the open bid, it will fly out immediately, without hesitation.
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WHY don't trees perish in winter?
Cause of the cell sap patterns. The cell sap of trees accumulates sugars that lower the freezing point of the sap, preventing it from turning into ice. Moreover, the plant's cellulose itself is a good insulator.
Yet severe frosts can lead to the death of the tree. And plants are the most vulnerable after harvesting, since most of the minerals and sugars go to the formation and growth of fruits, and in the trunk cells they are present in minimal quantities.
Cause of the cell sap patterns. The cell sap of trees accumulates sugars that lower the freezing point of the sap, preventing it from turning into ice. Moreover, the plant's cellulose itself is a good insulator.
Yet severe frosts can lead to the death of the tree. And plants are the most vulnerable after harvesting, since most of the minerals and sugars go to the formation and growth of fruits, and in the trunk cells they are present in minimal quantities.
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WHY are there no parachutes on civil aircraft?
First, most accidents occur during takeoff and landing, and at altitude there is no oxygen for breathing. Secondly, a successful parachute jump requires special training, and if you try to jump out of an airliner in a crowd of passengers, the chances of rescue are close to zero.
Instead of supplying passengers with unreliable personal rescue equipment, it is more effective to invest in improving flight safety in general.
First, most accidents occur during takeoff and landing, and at altitude there is no oxygen for breathing. Secondly, a successful parachute jump requires special training, and if you try to jump out of an airliner in a crowd of passengers, the chances of rescue are close to zero.
Instead of supplying passengers with unreliable personal rescue equipment, it is more effective to invest in improving flight safety in general.
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WHY doesn't it tickle when you tickle yourself?
The brain decreases skin sensitivity
Tickling is caused by irritation of the tactile receptors on the skin. Their sensitivity is controlled by the spinal cord and brain. If the irritation is caused by touching another part of your own body (which the receptors in the part being touched tell the brain), the brain dulls the sensitivity of the receptors, preventing the tickle from occurring.
The brain decreases skin sensitivity
Tickling is caused by irritation of the tactile receptors on the skin. Their sensitivity is controlled by the spinal cord and brain. If the irritation is caused by touching another part of your own body (which the receptors in the part being touched tell the brain), the brain dulls the sensitivity of the receptors, preventing the tickle from occurring.
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WHY and how do people hear the inner voice?
Speech is formed in childhood, first as an external voice (the child says everything out loud), and then it is interiorized (becomes internal). The nerve impulses to the vocal cords are essentially the same, but weaker, than those of audible speech. The processes of speech and thinking develop together; we form verbal-logical thinking.
These are our almost nonstop "inner voices." When the inner voice speaks, we are essentially thinking, and some of the nerve impulses run through the familiar pathways of speech. This is how we experience this "phantom" speech of ours.
Speech is formed in childhood, first as an external voice (the child says everything out loud), and then it is interiorized (becomes internal). The nerve impulses to the vocal cords are essentially the same, but weaker, than those of audible speech. The processes of speech and thinking develop together; we form verbal-logical thinking.
These are our almost nonstop "inner voices." When the inner voice speaks, we are essentially thinking, and some of the nerve impulses run through the familiar pathways of speech. This is how we experience this "phantom" speech of ours.
WHY is dust not useless?
Although some people think dust is an inconvenience, it actually keeps people alive. It plays an essential role in the condensation of moisture, resulting in rain and fog, which are necessary for plant growth.
Moreover, thanks to the property of atmospheric dust to scatter light, the eyes of earthly creatures are not exposed to the blindingly bright light of direct sunlight and we can observe beautiful sunsets and sunrises.
Although some people think dust is an inconvenience, it actually keeps people alive. It plays an essential role in the condensation of moisture, resulting in rain and fog, which are necessary for plant growth.
Moreover, thanks to the property of atmospheric dust to scatter light, the eyes of earthly creatures are not exposed to the blindingly bright light of direct sunlight and we can observe beautiful sunsets and sunrises.
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WHY do flying Frisbee plates bear their name from a brand of pie?
In the 1950s, Yale students were fond of throwing Frisbie Pie Company tin coasters at each other. The name "Frisbee" was so popular with students that the Wham-O Company, which invented the plastic "flying saucers," gave them the name Frisbee.
One letter was changed to avoid trademark claims.
In the 1950s, Yale students were fond of throwing Frisbie Pie Company tin coasters at each other. The name "Frisbee" was so popular with students that the Wham-O Company, which invented the plastic "flying saucers," gave them the name Frisbee.
One letter was changed to avoid trademark claims.
WHY do passengers crave tomato juice on planes?
According to experts, about a quarter of passengers choose this drink. It turns out that there is a perfectly logical explanation.
The thing is that at an altitude of 10,000 meters above the ground, a person's taste buds start to work a little differently. Due to pressure and dry air, salt and sugar lose their taste by about 20-30%.
Correspondingly, in order to experience the familiar taste, passengers choose drinks that seem too salty on the ground. Or sour, like tea with lemon. Besides, tomato juice helps to maintain water-salt balance during the flight.
According to experts, about a quarter of passengers choose this drink. It turns out that there is a perfectly logical explanation.
The thing is that at an altitude of 10,000 meters above the ground, a person's taste buds start to work a little differently. Due to pressure and dry air, salt and sugar lose their taste by about 20-30%.
Correspondingly, in order to experience the familiar taste, passengers choose drinks that seem too salty on the ground. Or sour, like tea with lemon. Besides, tomato juice helps to maintain water-salt balance during the flight.
WHY does water flow in different directions in the Northern and Southern Hemispheres?
The effect is attributed to the rotation of the Earth and the Coriolis force.
The Coriolis force is an inertial force that acts on a material point as it moves relative to a rotating reference frame. It causes objects moving along the Earth's surface to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. In the case of flowing down an inclined concave surface, this will give counterclockwise and clockwise motion, respectively.
Still, here is a crucial factor - the degree of influence of this force. And it depends, on the one hand, on the shape of the funnel and adjacent surfaces, on the other hand, on the parameters of the flow and latitude. In other words, the smaller the scale of the flow and the closer to the equator we are, the more microscopic is the influence of the Coriolis force on the background of other forces.
The effect is attributed to the rotation of the Earth and the Coriolis force.
The Coriolis force is an inertial force that acts on a material point as it moves relative to a rotating reference frame. It causes objects moving along the Earth's surface to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. In the case of flowing down an inclined concave surface, this will give counterclockwise and clockwise motion, respectively.
Still, here is a crucial factor - the degree of influence of this force. And it depends, on the one hand, on the shape of the funnel and adjacent surfaces, on the other hand, on the parameters of the flow and latitude. In other words, the smaller the scale of the flow and the closer to the equator we are, the more microscopic is the influence of the Coriolis force on the background of other forces.
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WHY do cheeks turn red in awkward situations?
Feeling ashamed or embarrassed is an extreme situation for the body. Adrenaline, a hormone released, kicks in, taking an active part in the "fight or flight" decision.
By worrying, we get into a defensive position, as if protect ourselves. Especially adrenaline prepares the body to cope with danger: it intensifies the heartbeat, speeds up breathing, increases pupils to get as much visual stimulus as possible.
Adrenaline lowers the digestive process, so energy moves to the muscles, blood vessels increase there, the flow of blood and oxygen speeds up, getting to all corners of the body faster.
Feeling ashamed or embarrassed is an extreme situation for the body. Adrenaline, a hormone released, kicks in, taking an active part in the "fight or flight" decision.
By worrying, we get into a defensive position, as if protect ourselves. Especially adrenaline prepares the body to cope with danger: it intensifies the heartbeat, speeds up breathing, increases pupils to get as much visual stimulus as possible.
Adrenaline lowers the digestive process, so energy moves to the muscles, blood vessels increase there, the flow of blood and oxygen speeds up, getting to all corners of the body faster.
WHY do swifts never touch the ground?
Swifts can neither walk nor swim: their feet are not suited to any kind of movement. At best, if suddenly found on the ground, a swift can crawl a few meters. It cannot even fly from the ground since the wings are far too long while the legs are quite short. The only exception is black swifts, they can jump up to take off.
Swifts feed on "air plankton" - small flying insects. They drink, wash, and mate in flight. And to leave offspring, they nest under roofs or in walls. Swifts live about 20 years, spending all these years in the sky.
Swifts can neither walk nor swim: their feet are not suited to any kind of movement. At best, if suddenly found on the ground, a swift can crawl a few meters. It cannot even fly from the ground since the wings are far too long while the legs are quite short. The only exception is black swifts, they can jump up to take off.
Swifts feed on "air plankton" - small flying insects. They drink, wash, and mate in flight. And to leave offspring, they nest under roofs or in walls. Swifts live about 20 years, spending all these years in the sky.
WHY do rockets count down when launching?
A countdown is an elaborate set of procedures culminating in the ignition of a missile's engine. Depending on the type of vehicle used, the countdown can start from 72 to 96 hours before launch time.
The film Frau im Mond, based on Jules Verne's novel From the Earth to the Moon, was directed by Fritz Lang in 1929. Heroes there had to launch to a satellite of the Earth not in a core, but in a rocket. To maximize the tension, the director and invented the countdown. The film had a great deal of popularity in Germany, and the German rocketeers, who were just testing their first rockets at the range, began to use this countdown.
At first it was just a ritual, but as the complexes got more complicated, so did the technological function: many people were working at the launch site, and everyone was performing their operation at a certain count.
A countdown is an elaborate set of procedures culminating in the ignition of a missile's engine. Depending on the type of vehicle used, the countdown can start from 72 to 96 hours before launch time.
The film Frau im Mond, based on Jules Verne's novel From the Earth to the Moon, was directed by Fritz Lang in 1929. Heroes there had to launch to a satellite of the Earth not in a core, but in a rocket. To maximize the tension, the director and invented the countdown. The film had a great deal of popularity in Germany, and the German rocketeers, who were just testing their first rockets at the range, began to use this countdown.
At first it was just a ritual, but as the complexes got more complicated, so did the technological function: many people were working at the launch site, and everyone was performing their operation at a certain count.
WHY cannot kangaroos jump in reverse?
Kangaroos are among the best jumpers in the animal world, with a jump length of 10-12 meters and travel speed of 50 km/h. To keep its balance when jumping, the kangaroo uses its thick, muscular tail at the base for balance.
This tail, as well as its large feet, is the reason why the kangaroo cannot jump backwards.
Owing to this fact, the kangaroo, in company with the emu, which also cannot stagger, appeared on the coat of arms of Australia, illustrating the motto "Australia always goes only forward!"
Kangaroos are among the best jumpers in the animal world, with a jump length of 10-12 meters and travel speed of 50 km/h. To keep its balance when jumping, the kangaroo uses its thick, muscular tail at the base for balance.
This tail, as well as its large feet, is the reason why the kangaroo cannot jump backwards.
Owing to this fact, the kangaroo, in company with the emu, which also cannot stagger, appeared on the coat of arms of Australia, illustrating the motto "Australia always goes only forward!"
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