Why is the temperature 40 ° C like entering the steamer, but the bath water is 40 ° C but does not stew itself like an iron pot?| NO.325
Author:Institute of Physics of the Ch Time:2022.09.16
The temperature is really amazing that the same temperature in summer and winter feelings are completely different, and even the same season feel is different. Why do you feel that you do n’t have to do it at 40 ° C at 40 ° C, you feel that you have entered the steamer? Q1's portable objects are still quiet and do not work, but still feel tired. Where did this energy consume? By Anonymous Answer:
When I was in junior high school, the teacher said, "People are a very complicated research object, because people are not a simple force or force -casting object, people will work hard." Things, skeletal muscle cells need energy to keep shrinking. Although people do not work directly on objects, the chemical reactions in skeletal muscle cells require energy and a lot of fever and energy. These energy need to be obtained from food -that is, tired and hungry.
BY Tibetan
Q.E.D.Q2 Why can clouds float in the air, and what kind of power offsets gravity? by Yang Li:
First of all, there must be a understanding of the cloud: the cloud is not a gas, but it is composed of tiny droplets and ice crystals (Yun also has a lot of knowledge, the specific classification depends on the reference materials). When the sun illuminates the ground, the water will evaporate into water vapor. As the temperature of the height increases the temperature of the environment, it will also encounter some tiny particles, so that the water vapor will form a small water droplet at the particles to turn into what we see. The cloud.
The key is to come, in fact, the cloud is not as calm from the ground, and its own dynamic balance is existing.
Dynamic process: The small water droplets in the cloud high condensed into raindrops. When it fell to the bottom of the clouds, the height decreased temperature rising. Because the quality of small water droplets was not large enough, the small water droplets would be evaporated back to the height of the cloud. After a period of time, after a period of time, after a period of time, after a period of time It will condense into small water drops. Of course, during this dynamic process, water droplets will decrease very low due to air resistance. (The air resistance can be calculated with the Stocks law. Let R is a droplet radius, υ is its relative coefficient, and η is the viscosity coefficient inside the cloud. : F = 6π 当r, when air resistance and gravity offset, the rate of water droplets will not increase)
In the end, in fact, the cloud will fall down. Now we name this magical meteorological phenomenon "rain"!
Reference materials:
Isn't the cloud in front of me? What is the cloud you said ...
by Justu
Q.E.D.Q3 Why does the raindrops seeing from outside the car fall vertically, and the raindrops sitting in the driving car are obliquely dropped? BY dust is not answered:
Jun did not hear "Rain Heng Wind March March Twilight" and "Divine Rain invasion of 薜 荔"? From this point of view, the raindrops outside the window look "vertical", after all, because the wind is not big enough
Speaking back to home. This is a very typical relative reference system: In the ground reference system, the raindrops at a rate
Considering the transformation and speed of the reference system, the synthesis and decomposition of speed is the details introduced in high school physics. If you answer this question in a lighter language, it is: when you take a car, you will see the sidewalk tree backward, and the raindrops will be the same; except that the raindrop drops backwards and falls backwards, it looks like it is inclined. BY Tibetan
Q.E.D.Q4 Why is it difficult to bear the environmental temperature of 40 degrees, but it is very comfortable to take a bath water at 40 degrees? By Anonymous Answer:
Because we are soaked in the air, and we only stand in the water when taking a bath.
We assume that the environmental temperature in the topic refers to temperature. People are constant temperature animals, and body temperature is healthy within normal range. When the temperature exceeds the body temperature, the human body can only evaporate heat dissipation, which requires a lot of sweating, the heart load is increased, and at the same time cause the loss of water and electrolyte. If the environmental sultry causes sweat to evaporate and the temperature of the human body has to rise, it will cause heat stroke or even fever.
In addition, the environmental temperature and body sensing temperature are often large. The body sensing temperature is mainly related to temperature, humidity, wind speed, etc., and there is a general converting formula [1]. The temperature is measured at 1.5m from the ground. It is measured in a louver with direct sunlight and rainproof and ventilated. This means that when the temperature is 40 ° C, the body feel is often much higher than the temperature. a bit.
In the upper formula, AT is somatosensory temperature (° C), T is temperature (° C), E is water voltage (HPA), V is wind speed (M/s), and RH is relative humidity (%). According to this formula, the temperature is 40 ° C, the wind speed is 2m/s, and the relative humidity is 80%, and the somatosensory temperature is 50.55 ° C. With such a high temperature, it is naturally difficult to bear the heat dissipation of the human body.
Let's talk about taking a bath. When taking a bath, hot water slightly higher than the body temperature is the most suitable, because hot water is easier to wash off the oil on the skin surface than cold water, and it will expand the capillaries on the surface of the skin and promote blood circulation. It feels very comfortable. However, because the temperature in the bathhouse is not higher than that of body temperature, and a large amount of water can help us evaporate and heat dissipation, it is not as unbearable as the temperature is 40 ° C. However, the bathhouse is very humid and easy to be hypoxic. It will still be uncomfortable after a long time. It should not be washed for too long. The editor felt that when I washed out of the bathhouse, it was the most comfortable moment of bathing, because the physical temperature at this time was the most suitable. Therefore, the 40 ° C bath is comfortable because the heat dissipation is not blocked. If you are soaked in hot water at 40 ° C, it will soon be unbearable.
Reference materials:
[1] Robert G. Steadman. A Universal Scale of Apparent Temperature [J]. American Meteorology Society, 1984.
by yellow water machine
Q.E.D.Q5 can see the same clouds at most? By Superchao Answer:
As long as the artist is willing, you can see the same cloud from Sugawa -cho (Fei Shi City) to Tokyo
The straight line distance of these two places is about 240 kilometers. Let's calculate whether these two places are likely to see the same cloud. Assume that the length of the cloud is D, it floats in the air of high H, ignores the problem of visibility, and assumes that the field of view is wide and unobstructed, then the only limit is the shape of the earth. According to the simple geometric relationship, the ground distance that its two edges can cover
We might as well choose a rainy cloud, it is high enough and thick enough (welcome to review NO.314 Q4), take
BY Shepherd
Q.D.Q6 sound transmission speed is related to the temperature of the medium? Why are some medium temperatures higher, the larger the sound speed, the higher the temperature of the medium, but the speed of sound? by Tianping Answer:
The sound is spread by mechanical vibration. Intuize it. The speed of the vibration transmission is related to the "response" of the medium. The more timely it is, the more time the sound is, the faster the sound is passed. For air, the interaction between molecules mainly rely on collisions. Educational temperature will make the gas molecules more active, the collision is more frequent, and the transmission of vibration is faster. And if you look at mercury, the distance of each mercury atom is relatively close, and there is a strong Curon power without collision, but the increase in temperature will make the distance between the atoms larger (think of mercury thermometers), and the interaction will weaken the interaction. , So it will make the transmission of vibration slowly.
Feel it? The sound speed mainly depends on the interaction of the interconnection in the medium. However, some things are not so -called "intuitive feelings" to accurately express. Although some of the sciencers I admire "formula +1 readers are halved", in accordance with a rigorous (number of words) The classmates are quantitative. The formula of sound speed is (derivative [2])
Among them,
For the ideal gas, its state equation is
However, the temperature of the ideal gas will change during thermal warming process. The equation it follows is
Well, you can see that the sound speed of the ideal gas is proportional to the 1/2 of the temperature, and it is very consistent with the measured value. For less ideal gas, as well as Fan Formula, the conclusions obtained are similar. For liquid, such as water, alcohol, mercury, etc., they will show the higher the temperature, the lower the temperature, the lower the temperature. At present, there is no uniform theoretical model for liquid and solids, and most of them rely on experience formulas.
Reference materials:
Speed of Sound
What is the formula for formulating (sound speed) in the air?
Ko, Jae-Hyeon. (2010). Comparison of Acoustic Behaviors Between Ethanol and Partially-Deuterated Ethanol. Journal of The Korean Physical Society - J KOREAN PHYS SOC. 56. 10.3938/jkps.56.409.
Air -Speed of Sound vs. Temperature
BY Shepherd
Q.E.D.Q7 From the perspective of physics, how to distinguish between micro and macro?
by snowman
answer:
The macro and micro -boundary of physics are not absolute. There is no line in the interval of small to nano and long -term light years. The line is "macro" and offline is micro. In fact, physicists determine macro and micro according to their research objects and research standards. For condensate physicists who need to consider interaction between atoms and molecules, a few millimeters or even a few millimeters of superconducting are typical "macro quantum effects"; for engineers who do metal materials, the structure of the magnetic domain may be possible. It can also be counted as micro; for the atmospheric physicists who have studied complex systems (after the Nobel Prize was issued last year, most people should think they are physicists ...), and a whirlwind in diameter of ten meters is beyond doubt It belongs to the micro ...
If you want to ask the division of classic mechanics and quantum mechanics, then it can indeed be a relatively clear criterion. Generally speaking, the physical quantities described by quantum mechanics can be written into (scheduled) Planck constant
Q.E.D.Q8 even the black hole that cannot escape from the light. In some articles, some rays will be sent. Why? By Anonymous Answer:
Because the place where these rays are generated are not in the incident. Only the time and space in the vision can be distorted and can only fall inward inward, and the material and energy outside the horizon can still escape.
For example, the X -rays emitted by the black hole, it comes from the suction disk around the black hole. The accumulation disk is like the ring of Saturn, which is the substance captured by the gravitational gravity of the black hole. The material falling is not a sloppy fall, but a spiral movement to the heart, just like the vortex of the lower water mouth. In the process of falling, the relative speed difference between material is very different. They rubbed violently, so the temperature is very high, and the X -ray will be released.
In addition to electromagnetic rays, the two poles of the black hole will also form a relatively argument, and its speed can reach more than 99%of the speed of light. The current mainstream theory believes that these jets are composed of plasma. It comes from the substance that is ionized in the accumulation disk, and converges to the bipolar of the black hole under the action of magnetic fields, and then jets to the distance. Its jet length can reach thousands of light years.
Both X -rays and jets have been observed. In addition to these two types, there is a "evaporation" method widely accepted by the academic community, which has been widely observed, but also Hawking radiation. The quantum field theory pointed out that vacuum is not empty, but continuously produces positive and negative particles and annihilated back. This is called the quantum rising and falling in the vacuum. This has also been confirmed by the Casimir effect in the experiment. If a pair of positive and negative particles happened near the horizon of the black hole, but before falling back, the anti -particles fell into the vision and annihilated with the positive material in the field of vision, then the remaining positive particles could escape. It looks like the quality of the black hole runs outside the field of vision, but there is no material out of the vision.
Reference materials:
The giant galaxy artand the giant black house
What causes the relative theory to extend from the black hole, what do they constitute?
Physicist Identify the Engine Powering Black Hole Energy Beams | Quanta Magazine
BY Shepherd
Q.E.D.#Voting#q q q q q
Tibetan idiots, justiu, yellow water machine, sheep sheep
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#The last issue is also wonderful
Edit: Mu Zi
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