First, water does not work on the skin as water does on stone (hard objects).
First, to understand the composition of the hand skin. The skin of the hand consists of epidermis, dermal and subcutaneous tissue with a thickness of about 0.5-4MM.
Skin epidermis
The epidermis can be divided from outside to inside: cuticle layer, transparent layer, granular layer, spiny thorn layer, and base layer.
Corium layer
It is divided into reticulate and nipple layers, containing blood vessels, nerves, lymphatic tubes, sweat glands, and sebaceous glands. The dermis has no ability to regenerate and is difficult to repair once damaged.
Cortical membrane
At the top of the epidermis is the upper weak acid protective film, which is made of sebum + sweat + cuticle composition, which can play a good waterproof role.
The moment of water drops as the first place of the answer is the physical effect, the countless superposition of the pressure of the bubble. The moment of pressure is a single direction of force for the stone, that is, the whole effect of force is concentrated on a certain point or a small area, the force area is small, by a huge pressure countless superposition eventually causes damage.
But …
The skin, subcutaneous tissue, and muscles are ductile, scalable, elastic, and of a certain thickness. When the water drop, the effect of pressure is not acting on the instant contact area of the skin, because of the skin, subcutaneous tissue, muscle characteristics, in the moment of the invisible concave, and due to the uneven characteristics of the skin itself, fully and the surface contact of the water drop, force surface area increases, force instantly dispersed, the force is smaller, less than the force of the stone.
It not over yet …
In the long term of water droplets, the outermost sebum film is removed by water droplets, so the skin begins to absorb water. The epidermis is not completely closely «sticky» with the dermis, the skin is only «bound» to the dermis by the connective tissue, not in some places; so when the skin is «swollen», the «bound» is confined and depressed; from the appearance, the skin surface is concave and abrupt, like wrinkles.
That is to say, the effect of pressure on the skin will be less and less because the folds of the skin constantly increase the force area, buffer increases, bubble force easier and easier to be dispersed. Therefore, the bubbling force of water droplets is very small, impossible to cause damage, no repair.
But …
This is the hand, not a stone, which cannot be considered only from a physical standpoint. The changes in the epidermis after adequate water absorption have folds and are softened. Besides that, there will be a more significant change if it is cold water, the temperature will be more easily transmitted, the blood vessels shrink, and your hand will change again much longer and get frostbite. This is caused by vasoconstriction and thus reduced blood flow, causing the tissue to have ischemia, hypoxia, and damage to the cells.
If the water drop has not yet stopped…
Your palm causes irreversible damage, and seriously the whole-cell tissue of the hand dies from a severe lack of oxygen.
Continue the hands …
Since the epidermis is already filled with water, the dermal cells have died, the biological activity of the cell membrane is completely lost, and the properties of selective absorption no longer exist. Because the intracellular concentration is greater than the concentration of external water, the extracellular water enters the cell, the cell volume increases, and finally breaks up. The blood has stopped flowing, so it is not discussed. Lymph tissue also began to seep water. Now your hand is not only waste but also particularly swollen!
If this crazy experiment is not over?
Sorry, I can only think of this place …
(The self-repair of cells that have been frozen to death has no repairability.)
Conclusion：
Dridripping enough for long enough, longer than you think, —— Yes.
Or rigorous, first of all, the role of physical opponents has been ruled out, because the epidermal tissue is more and more softened with the infiltration of water, the dispersion of the force will be stronger and stronger, but softening has a certain limit, but before this softening is reached, already enough for the bubbling force of the water droplets is completely dispersed.
That’s why you feel it hard to wrap the egg completely in the palm, and also crush it.
Secondly, I make a more detailed hypothesis about this experiment:
Set the two variables:
1. Waterdrop temperature ; 2. Environmental temperature
Quantified is the hands of an adult male with mature thermoregulation, with water drop intervals once per second.
Suppose 1
The temperature of water droplets is below the human temperature, and the room temperature is about 20 degrees,
as described above.
Suppose 2
The water drop temperature is equal to or slightly above the human temperature, and the room temperature is about 20 degrees
Water droplets do not heat the skin because the temperature is comparable. However, with the increasing number of water droplets, more and more water on the skin surface, the water has a strong thermal conductivity, the heat of the water will be transmitted to the air first, the cooling water and then absorbs heat from the skin. The skin tissue is still frozen.
The results were still as described above, only longer.
Suppose 3
The water droplet temperature is about 20 degrees above the body temperature and is about 20 degrees
Water droplets transfer heat to the skin within the first dozens of drops, but due to the increasing water on the hand, the heat of the water droplets is dispersed by the existing water the moment it drops to the hand. When reached, the water temperature will be below the temperature.
The results remain as described above, only longer.
Suppose 4
The water drop temperature is ≥ 80 degrees, and the room temperature is around 20 degrees
If the man was fastened to a chair and his hands bound to move, OK. The trial continued… The results were still above but burned and small before frostbite.
Just that it takes it longer and longer.
Suppose 5
The condition of changing the room temperature is high temperature, higher than the water temperature, assuming no wind. At this time, the temperature of the water is controlled under the balance of body temperature and ambient temperature, maintained within the body temperature range.
But …
Water will evaporate, the evaporation of the water will still absorb heat, so the temperature of the skin on the hand will still drop. And due to the continuous drop of water droplets, so that the water on the hand remains within a certain range of quantity, the heat of the air is not directly transmitted to the skin.
But …
Since the torso is maintained in the 37 ° range (in high temperatures), heat is transmitted to the palm through the trunk. Under the regulation of the body temperature, the palm is not frostbite.
But …
In a long-term hot environment, people will get heatstroke…
(The above assumptions are based on infinite time.)
Anyway, in short, it is waste (the human body can not stay steady).
Add it again:
The human body can maintain certain conditions for a stable state, within a certain range (animals have an isothermal zone, maintain the dynamic balance of temperature regulation, beyond this range or below this range, the ability of the body temperature regulation is not enough to maintain the balance, will produce stress reaction) once under a long time, even if the weak change (such as absorbing a small amount of heat), long time will inevitably lead to the body steady state (such as temperature regulation system) is broken, is only a matter of time.
Attach: Popular science article 《dripping drop wears a stone and» empty bubble》
Why can the water dripping wear the stone?
A common saying is that because the water droplets constantly impact, each impact on the stone produces very small damage, over time, you can wear the stone. Why can a drop of water make the stones to cause small damage? Suppose we change the water droplets into table tennis, let the table tennis one by one constantly falling on the stone, can we «wear the stone»? The answer is no. Although the wooden table tennis table is worse than the stone, no matter how many years a table tennis table is used, the wear of the middle part is never serious than the edge part, and the impact force of the table tennis is more than the water drops. It can be seen that the «stone wear» is not only to rely on the «waterdrop» rush Click on it. So what is the well-known phenomenon of «water dropping through the stone»? Scientists used a high-speed camera taking 1,500 photos per second to solve the process. Originally, the drops were first flattened and then scattered around, creating countless tiny bubbles between them after hitting the ground and falling apart with minimal surface tension. When the bubble shrinks, compress the air inside the bubble, so that the air inside the bubble has The larger pressure, the smaller the bubble radius, the greater the gas pressure in the bubble. When these small radius bubbles burst, the internal high-pressure gas hit the stone, causing minor damage to the stone, and finally «pierced the stone,» physically called gas erosion, or «empty bubbles.» When the first ocean-going ships of the 20th century were launched for trials, it was found that after just 12 hours, the propeller was ineffective and the whole propeller was full of holes. Engineers searched carefully for the «perpetrators» but never solved the case for a long time. Later, with the help of the scientists, after years of observation and The study has confirmed that this is caused by air erosion. The «criminal» who destroys the propeller is the bubbles produced when the propeller rotates at high speed. Due to the rapid propeller speed and the great impact on the water, a large bubble cloud was formed around the propeller, tiny enough to be discerned by the naked eye. The air pressure in the blister with a very small radius is great, and the pressure produced when the blister breaks can reach thousands of atmospheric pressure. Countless small bubbles break, under the continuous impact of high-pressure gas, light reduces the propulsion efficiency of propellers and heavy damaging metal components. Scientists think of it as Fighting with air erosion, such as improving the nature of metal materials to be afraid of «air erosion», coating the propeller with a layer of chemical protection to reduce bubble production and erosion. Scientists also greatly reduce the effect of air corrosion by developing small bubbles into so-called superbubbles. What is it? When an object moves in water at more than 50 m/s, low-head voyages or gas-mounted injection systems may produce low-density holes known as «superbubbles». The length of the «empty bubble» is related to the velocity of the object, and the object can move in itself The resulting long bubbles advanced inside with minimal resistance and the discovery of superbubbles encouraged ship designers. They designed superbubble propellers so that the propeller blade surface was completely covered with gasified water molecules, without less propulsion efficiency and donation of the propeller blades. Russia developed the successful «Blizzard» torpedo in the 1990 s, a submarine high-speed torpedo at a speed of up to 500 km/h. When it moves in the water, the air is discharged from the head, and the thunder body surface is covered by air bubbles, so the resistance is extremely small, and the operation speed is extremely fast. The United States Navy underwater work The center has experimented with an underwater superbubble bullet, its flat head, an unpowered ejection, fired by underwater machine guns, the initial speed of 1 500 m/s, far beyond the speed of sound, ship designers have developed the idea of using superbubble ships. The so-called super empty bubble ship is to make the whole ship submerged surface covered by air bubbles, the ship body is not immersed in water but immersed in the super empty bubble so that it becomes a super empty bubble ship. Superbubble ships receive less water resistance, which can greatly increase their navigation speed. A researcher at the Marine Engineering Laboratory at the University of California in Santa Barbara proposed The idea of the waterfowl, where the surface of the wings is covered by gas so that the friction resistance of the wings is greatly reduced and the speed of the ship can double on the existing basis. Most notably is the idea of building the submarine. The so-called superbubble submarine is to make the whole boat body covered by bubbles, the submarine boat body is not immersed in water. In this way, the friction resistance suffered by the submarine disappeared, greatly reduced resistance and accelerated navigation speed.
Then, I think the human skin is self-repair ability, so although water droplets fall will have high-pressure gas damage the skin, but our body will soon repair and update ~ Also, said the bad propeller what is because of fast speed and other factors, water droplets are very slow, the effect is not obvious.
