# Tag Info

2

It's because normal ice, ice Ih, is less dense than liquid water. Ice Ih forms hexagonal crystals. The bonds in that crystalline structure make the water molecules slightly further apart than they are in the liquid form at the same pressure. That water expands on freezing makes water resist freezing as pressure increases. This in turn makes the fusion point ...

0

It seems that most places I've read (on the web) people refer to the depressurization of water (in a vacuum or space) as "boiling" but I have very rarely seen this referred to as an out-gassing of the water's internal dissolved gases (nitrogen, oxygen, CO2, or any other gases that may be used in a space vehicle). However, unlike traditional boiling which ...

8

Steam is caused when water vapor condenses. This is caused by the air having too much water vapor for it to hold. When you have a lot of heat under the pan, the air above the pan is quite hot and can hold a lot of water. The water evaporating from the pan disperses into the atmosphere and doesn't condense. When you turn off the heat, the pan and food ...

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I answer my own question and give a good thanks to DavidPh, who has not really gave the answer, but in fact, it was impossible for him to give it. Here is "why": I'm French, so I've many fire hydrant data but from France. And when applying them to the formulas, the result was wrong... In fact, the problem is not the formula but the way we measure the ...

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The discrepancy is that the pressure as measured by the Pitot tube is not just the kinetic energy term of the pressure, but instead is a combinaiton of static pressure and the kinetic energy term. See if pages 16-34 of the following reference are helpful, though not metric: http://www.southsaltlakecity.com/uploads/documents/%5E_Fire_Flow_Calculations.pdf ...

1

Due to evaporation a layer of air forms between the water droplet and the hot surface which causes the system to vibrate by letting air escape in bursts and produce sound. I suggest reading about the description of the sound that was recorded in the Leidenfrost experiment. Article: http://www.nature.com/srep/2012/121010/srep00720/full/srep00720.html Video: ...

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For the answer I will make two assumptions: in both pots the amount of water is enough 1) to get all the salt into solution and 2) to not get absorbed completely by the dumplings. Say pot A has less water than pot B than the concentration of salt in pot A will be higher. If the dumplings are initially dry, they will absorb water and the dumplings in pot A ...

1

Well, in the pot with less water you'll have more salt spread through a smaller volume than the other pot. That means the water will be saltier in the pot with less water. I don't know the salt transfer rate for a solution to dumplings, but I would assume the one with a higher salt-to-water ratio would be saltier.

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Even assuming all of the energy it gains is turned into thermal energy (heat) it's just too small to worry about. $$\Delta KE = mg \Delta h$$ Let's assume it falls $2m$. $$\Delta KE = mg (2m)$$ Given that energy, we can compute the heating of the water. $$Q = m C_p \Delta T$$ $$\Delta T = \frac{Q}{mC_p}$$ $C_p$ for water is $4.18 \frac{J}{gK}$ \Delta T ...

1

Temperature doesn't rise as an object falls. Temperature is just the average kinetic energy of the individual particles within an object, but their individual velocities is random. A water droplet falling is an ordered falling that you can consider as a form of work, and you feel it as the splattering on your feet.

11

The relative humidity of air is pressure dependent. Your method of popping your ears involves increasing the pressure of the air in your mouth. And if you sufficiently compress a volume of air that has a high relative humidity, you can increase the air's relative humidity beyond it's saturation limit, which causes the water vapor in the air to start to ...

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Summary: The best way to see the water is to try and look for the reflection of a light source (sun or light bulb) at a large angle of incidence. More Details: You see the water on your floor because it reflects light differently than the dry surface of the floor. Namely, the water forms a smooth enough surface that the light reflected off of it can be ...

3

I stumbled on this question rather late - and when the link to the image in @Georg's answer was no longer working I started a little digging of my own. I came upon the following plot (at http://www1.lsbu.ac.uk/water/microwave.html) which explains this very well: It shows unambiguously that water has a strong absorption peak in the "low GHz" range (right ...

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Several things to consider: The speed of sound is much higher in water than in air. Just how much depends on a lot of factors. On http://www.waterencyclopedia.com/Re-St/Sound-Transmission-in-the-Ocean.html it says: The state properties of water (temperature and pressure) and the degree of salinity also affect the speed of sound. The propagation of ...

2

If there's hardly any ice at all, the water will cool as the ice warms to 0°C, then cool some more as the ice melts. The cooling stops when the ice melts. If there's hardly any water at all, the water will cool to 0°C. If the ice is cooler than 0°C, that tiny bit of water will freeze. If there's an intermediate amount of water, the water will cool to 0°C ...

1

Yes, your analysis is correct. Water in equilibrium with ice is at a temperature of 0 degrees C. The reason that the water doesn't spontaneously turn to ice has to do with the latent heat of fusion of water: in order for water to turn to ice at zero degrees C, you need to remove quite a lot of heat from it. In the case of water / ice, the latent heat is ...

0

If you stick your finger in the water, the weight of the finger is still supported by you and so the weight of the beaker does not go up (it goes down a tiny tiny amount because the water rises and the height of the air above it goes down insignificantly.) If you cut off your finger, the weight goes up by one finger because you are no longer supporting it. ...

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The white cloud you see in the water is steam bubbles. The grains of salt provide nucleation sites that allow the water to vaporize as they fall through the superheated liquid (so BowlOfRed had it right--although it's steam that is forming, not dissolved gasses coming out of solution). If you raise a pot of water to near boiling and toss in a handful of ...

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Maximize the thermal contact between the heat source and the water Minimize the thermal contact between the pot and the environment Avoid (or recapture) evaporation (put a lid on it) Of course if you want to cook food quickly, you need a pressure cooker (temperature of water goes above 100 C and you get significant increase in cooking speed as the ...

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