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1

Ice floats. That's the reason life is possible in winter, when the lakes freeze: the water remains liquid under the ice, which floats (and forms) on the surface. This means $\rho_{ice} < \rho_{water}$, that is, ice is less dense than water ($\rho$ stands for density). If you take a certain mass $m$ of water and freeze it, then $$\rho_{ice} = ...


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Let's go back of the envelope here: I'm going to assume that your "original" volume of water is 6 oz (I think that's fairly standard for a cup of coffee/tea), but you add an "extra" 2 oz of cold water. (I'll refer to the amounts of these waters by the quoted titles throughout the answer to keep the language precise). Whether or not this water will be added ...


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It would most likely be less warm if you add more water. It is because heat is measured in calories or temp. 1 calorie is how much energy that is required to heat up 1cm3 water up one degree Celsius. So theoretically if I added more mass or water it would take more energy to heat up because 25 cm3 of water would less energy to heat up because it has less ...


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It will come out cooler if you add the extra water at the end. It could be a lot-if you literally mean it came out boiling hot at the end of 60 seconds, you could have used the last 15 seconds to boil water. If you had added the extra water at the beginning, it would come out at 100C. If you add it at the end the mix will be cooler. The extra heat in the ...


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Simple answer is no!! Blankets only work in air. Since air is a bad conductor of heat and blacnkets use this air to provide as a cushion for your heat and the external environment. Since in water there wont be much air and water too is a bad conductor of heat. Hence you should not use blanket in water


1

ice is less denser than water because in ice the molecules arrange themselves in a rigid tetrahedral structure due to which cage like spaces remain in their bonding. But water molecules remain in linear bonding form. As the volume of ice becomes greater, it is less denser.


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$T$ should be the actual temperature at which the water evaporates. That is, the temperature at the interface between the air and the water, not the boiling point. This is simply because $dU = TdS + pdV - \sum_i \mu_i dN$ (where $T$ is most definitely the temperature of the system), or by rearranging, $$ dS = \frac{1}{T}dU -\frac{p}{T}dV + ...


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Specific entropies ($\mathrm{kJ\,kg^{-1}\,K^{-1}}$): \begin{array}{lrll} & \mathrm{^\circ C} & \text{liquid} & \text{vapor} \\ \text{Triple point} & 0.01 & 0 & 9.155 \\ \text{Normal boiling point} & 100. & 1.307 & 7.355 \\ \text{Critical point} & 374.15 & 4.430 & 4.430 \\ \end{array}


1

Yes, electric current is movement of any kind of charges. The problem with your particular example is that most liquids containing ions are also conductive. Electrons will hop between molecules and equalize the ionic charges, then end up providing most of the conduction themselves. There are cases where actual ion migration results in much of the current, ...


1

Well, technically yes (assuming you mean ionized and not just "charged"). Current (in simple terms) is only the time rate of charge flow, which is not exclusively limited to electrons or any specific charge carrier. Electrolytic conductivity is well documented, naturally being higher for strong electrolytes as compared to the ones that dissociate weakly in ...


1

Ions can indeed carry current (ex. electrolysis). "An electric current is a flow of electric charge. In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in a plasma.[1]"


27

The sort of dishcloths generically known as J Cloths are made from a material called Viscose rayon: This material is derived from cellulose and like cellulose it interacts with water. Water breaks hydrogen bonds formed within the fibres. This makes the fibres softer, and the exposed hydroxyl groups make the surface more hydrophilic. It's the latter ...


2

I suspect it's a surface tension question. When a dish cloth is slightly damp, then water is already between the fibers. Putting a drop of water in touch with that fiber (and water), the water will be drawn from the drop into the space between the fibers. By contrast, if the cloth is really dry, then when the drop is touching the fiber, it first needs to ...


1

If all you did was drink distilled water, it would not be terribly healthy for you. But most people eat as well - and that combination probably includes "healthy" minerals. Unless you binge-drink distilled water without any food, it's unlikely to cause serious health effects. Having said that - ions are pretty small - certainly smaller than 15 nm. But their ...


3

The branch of physics that studies these problems is called "thermodynamics", and it is a very successful theory as it describes most bulk matter behavior and can be used in engineering and other projects reliably. In thermodynamics matter is composed of molecules modeled as classical particles with some collective properties that are defined by ...


0

For a given temperature and pressure, it is possible for a certain amount of liquid to be in the vapor phase. At any moment, water molecules from the liquid escape to the vapor; and at the same time some of the vapor molecules go back into the liquid. Equilibrium is established when the rate of these two processes is the same. At what (partial) pressure ...


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I suspect the little bubbles are actually CO2. CO2 is water soluble, and you could find it in most forms of tap water. "hard" water tend to have high concentrates of CO2 while softer water have less. If indeed this is the case, the bubbles form because it is energetically efficient to them to adhere to your hand, which is a lower energy state for them. I ...


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a liquid is not perfectly incompressible - see cavitation in fluids. still, i think we can assume that here . we can calculate the maximum possible height reachable. If i assume that the wall is perfectly rigid and it cannot move when the wave hits it, and if i also assume that the wave system is perfectly conservative , i.e: no energy is lost as heat or ...


1

Heavy Water is toxic to most organisms. Usually, an organism will die before half of their body's water has been replaced by heavy water (which would require ingestion of very large amounts of heavy water and limited ingestion of regular water). It's toxic because it inhibits cell division and slows down the rate of life processes. It would slow your ...


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 ...


0

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 ...


0

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 ...



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