Junior 2 Physics Boiling, Junior 2 Physics Why is the sound of water louder before boiling than when

Can 100 degrees Celsius water heat water that is not 100 degrees Celsius?

Yes; But it can only be heated to 100 degrees Celsius; The heated water can no longer absorb heat and will not boil after reaching 100 degrees Celsius.

No. Because heating is a process from low to high temperatures.

Yes; Normally, the boiling point of an ice-water mixture is 100 degrees Celsius at a standard atmospheric pressure.

If not 100 degrees Celsius. That means it's not at a standard atmosphere!

100 degrees Celsius heating can only be kept around 100 degrees Celsius all the time. And if you put 100 degrees Celsius water after adding water of other temperatures. If 100 degrees Celsius water is added to 120 degrees Celsius water, the temperature will be lower than 120 degrees Celsius.

OK; 100 water will increase the temperature of water up to 100 until they are the same temperature. Do you understand? ^^

Reduced pressure !! The boiling point of water decreases.

Hehe: That's an interesting question.

Whether you can or not depends on what kind of 100 degree boiling water you are.

If it is 100 degrees of water with a heat source (simply put, boiling water that is still heating), then it is possible to heat water that has not reached 100 degrees, but the heated water really does not boil, and the upstairs is very right.

If it's 100 degrees of water without a heat source, you can't heat water that doesn't reach 100 degrees Celsius to 100 degrees. Complete!

Yes, 100 degrees Celsius water can transfer heat to water that has not reached 100 degrees Celsius until they are at the same temperature, and no more heat transfer occurs.

Heat transfer and characteristics: Heat is always transferred from a hot object to a low temperature object until the temperature is the same. ）

I don't understand what this question means.

Yes, but the water temperature will drop to 100 degrees! Huh,

1. Before boiling, the temperature of each water layer is different, the temperature of the water layer near the heating surface is higher, and the temperature near the water surface is lower. In the process of rising, the bubble not only the air pressure in the bubble decreases with the decrease of water temperature, there is a part of the water vapor in the bubble condensed into saturated steam, the pressure is also decreasing, and the external pressure is basically unchanged, at this time, the external pressure of the bubble is stronger than the internal pressure, therefore, the volume of the bubble will shrink in the rising process, when the water temperature is close to the boiling point, a large number of bubbles emerge, rising one after another, and rapidly changing from large to small, so that the water oscillates violently, producing a buzzing, buzzing sound, this is the reason that the water does not open.

2. Continue to heat the water, because the convection and bubbles continue to bring the heat energy to the middle and upper layers, so that the water temperature of the whole dissolver tends to be consistent, at this time, the bubbles float on the wall of the detached device, and the saturated water vapor inside it will not condense, and the saturated vapor pressure tends to a stable value. In the process of bubble floating, the static pressure of the liquid on the bubble decreases with the decrease of the depth of the water, so the external pressure on the bubble wall is gradually decreasing compared with its internal pressure, the mechanical balance on the bubble liquid-air separation interface is destroyed, the bubble expands rapidly, accelerates the floating, until the water surface releases steam and air, and the water begins to boil. That is, people often say that the water is boiling, because the bubbles rise to the surface of the water at this time and burst, the oscillation of the water is weakened, and the humming sound is almost inaudible, which is the boiling water does not make a sound.

Instantly, it is generated in the air**, and then it is fused....(conjecture).

When the water begins to heat, the bottom of the kettle produces some small bubbles, these small bubbles are mainly formed by the air adsorbed at the bottom of the kettle and dissolved in the water In addition to the air in the bubble, it also contains the water vapor produced by heating, with the increase of temperature, the water vapor evaporated into the bubble gradually increases, its volume and pressure will increase, and it rises from the bottom under the action of buoyancy When the bubble rises to a lower temperature, part of the water vapor in the bubble condenses into water, and the pressure outside is stronger than the pressure in the bubbleAt this time, the volume of the bubble gradually decreases In the process of continuing to heat, the bubble is generated and expands more and more, and it is larger and larger, but when the bubble rises to a lower temperature, the water vapor in the bubble will condense into water, and the volume will gradually decrease Then in such a process, with the increase of temperature, the volume of the bubble expands for a while and shrinks for a while, and constantly floats, which will produce a vibration If the frequency of this vibration is the same as the natural frequency of the kettle, it will produce a resonance sound In addition, There are still bubbles running out of the water, so that the pressure of the gas in the space without water in the pot increases, and a part of the gas will be squeezed out of the gap between the lid and the body of the pot, and there will also be a sound, with the increase of temperature, the bubbles running out of the water surface will increase, and the air pressure will continue to increase The sound will become louder and louder Due to these two reasons, we will hear the sound of water at this time, and the sound of the water sound is getting louder and louder This sound is made when the water has not yet boiled, generally "hum, hum, hum......Voice

When the temperature of the water reaches the boiling temperature, the inside of the water is vaporized sharply, the water vapor in the bubble reaches saturation, the density atmospheric pressure is high, and its volume will not only not shrink in the rising process, but also continue to increase At this time, the buoyancy of the bubble also increases in the process of its rise, and the bubble rises from the bottom to the surface and bursts, releasing water vapor, the resonance between the bubble and the kettle does not exist, and the sound of the water sound becomes smaller Then a large amount of gas is discharged from the gap, and the large air pressure will lift the lid of the pot. After the lid is lifted, a part of the gas is discharged, and the pressure is reduced; It falls again under the action of gravity, and the air pressure increases again after the lid is lifted, and so on and so on, so it turns into a "horn, horn, horn...... of water vapor pushing the lid of the potIf the water in the kettle is not filled, the water surface is below the interface between the spout and the body of the kettle, or the gap between the lid is large, in this case, the water vapor pushing the lid of the kettle "horn, horn, horn...... will not be heardA large amount of water vapor will come out of the spout or cracks, and the sound is very small or even no sound, which is the physical principle of "boiling water does not make a sound, and the sound water does not boil".

That's a matter of tone, and then boiling the air column shrinks so the pitch is high, so the volume produced is also larger.

As the saying goes, boiling water doesn't make a sound, and the sound water doesn't boil.

When the water begins to heat, the bottom of the kettle produces some small bubbles, these small bubbles are mainly formed by the air adsorbed at the bottom of the kettle and dissolved in the water In addition to the air in the bubble, it also contains the water vapor generated by heating, with the increase of temperature, the water vapor evaporated into the bubble gradually increases, and the quiet accumulation and pressure next to the body will increase, and it rises from the bottom under the action of buoyancy When the bubble rises to a lower temperature, part of the water vapor in the bubble condenses into water, The external pressure is stronger than the pressure inside the bubble, and the volume of the bubble gradually decreases In the process of continuing to heat, the bubble is produced and expands more and more, and it is larger and larger, but when the bubble rises to a lower temperature, the water vapor in the bubble will condense into water, and the volume will gradually decrease Then in such a process, with the increase of temperature, the volume of the bubble expands for a while and shrinks for a while, and constantly floats, which will produce a vibration If the frequency of this vibration is the same as the natural frequency of the kettle, In addition, there are still bubbles running out of the water, so that the pressure of the gas in the space without water in the pot increases, and a part of the gas will be squeezed out of the gap between the lid and the body of the pot, and the sound will also be produced. Buzz talk about scum, buzz ......Voice

When the temperature of the water reaches the boiling temperature, the inside of the water is vaporized sharply, the water vapor in the bubble reaches saturation, the density atmospheric pressure is high, and its volume will not only not shrink in the rising process, but also continue to increase At this time, the buoyancy of the bubble also increases in the process of its rise, and the bubble rises from the bottom to the surface and bursts, releasing water vapor, the resonance between the bubble and the kettle does not exist, and the sound of the water sound becomes smaller Then a large amount of gas is discharged from the gap, and the large air pressure will lift the lid of the pot. After the lid is lifted, a part of the gas is discharged, and the pressure is reduced; It falls again under the action of gravity, and the air pressure increases again after the lid is lifted, and so on and so on, so it turns into a "horn, horn, horn...... of water vapor pushing the lid of the potIf the water in the kettle is not filled, the water surface is below the interface between the spout and the body of the kettle, or the gap between the lid is large, in this case, the water vapor pushing the lid of the kettle "horn, horn, horn...... will not be heardA large amount of water vapor will come out of the spout or cracks, and the sound is very small or even no sound, which is the physical principle of "boiling water does not make a sound, and the sound water does not boil".

Usually people think that the boiling point of water is 100, but this is not accurate, and it is used nowadays. But now I do the questions according to 100!

There is no relationship between the boiling point and the volume of water. In general, the boiling point of water is related to the pressure, and the higher the pressure, the higher the boiling point. At atmospheric pressure, water is saturated with steam at 100 degrees, but in the presence of pressure, water needs a higher temperature to saturate the water vapour.

Think about it, in a stressful situation, the molecular attraction of water molecules to break away from the surface of the water also requires a higher energy to escape, and this energy is to raise the temperature of the water.

Conversely, the lower the pressure, the lower the boiling point.

Also, the pressure is related to whose composition, such as impurities in the water!

I don't understand the question!

The first figure shows that water boils because the temperature of the water reaches the boiling point of 100 at atmospheric pressure

The second picture cools the flask with cold water, because of the thermal expansion and contraction (more precisely, the hot air in the bottle meets the cold cup wall liquefies, and the gas volume decreases,) at this time, the pressure in the bottle decreases, the boiling point of the water decreases rapidly, and the temperature of the water itself decreases slowly, higher than the boiling point at this pressure, so it boils again.

It's very simple, the teacher should have taught you that the boiling point of water decreases at high altitudes, and one thing is that the air in the bottle becomes colder and the pressure decreases, which is to simulate the low air pressure at high altitudes, so that the boiling point of water decreases and boils again.

The cold water lowers the temperature, the gas in the upper bottle shrinks, the pressure decreases, and the boiling point corresponding to the pressure reduction decreases, so that it can boil again at the current temperature.