# Tagged Questions

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### Why is it that in a warm shower water feels hotter near the head?

When the water first hits your body, it feels warmer than when it streams down towards your feet. I realize that part of this is due to the water cooling down by dissipation to the surrounding as it ...
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### How does the temperature in a bucket of water with ice change over time?

I'm curious what happens to the temperature of the water in a bucket of water with ice in it. Let's start with a bucket with just ice in it, and we add water, in a room which is room temperature. It ...
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### Why doesn't water in water barometer boil?

I have read that the pressure in a water barometer at the top of the water column is around 0.5 psi and at such low pressures water should boil at around ~26°C (Room temperature). [1] [2] How ...
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### How do heated showers/faucets work? [closed]

I'm not sure if this question is for Physics SE, but I'd go ahead and ask. I was wondering how the heated showers work (the ones with the hot and cold knobs). I have always been curious and this may ...
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### What is the deepest cause of the such high specific heat capacity of water?

Yes, I know about the hydrogen bridges. But I think, it isn't the deepest cause. Anyway, they are only second-order bindings, although quite strong. I think, somehow should have the water a ...
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### Hot water freezing faster than cold water

This question has puzzled me for a long time. There is already a question like this on Physics.SE. John's answer to the question seems quite satisfying. But when I googled the cause I found this and ...
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### How much energy would it take to maintain the temperature in my pool?

Lets sat that I have a 1000 gallon pool sitting pretty at 82.4 degrees F (28 C). How much energy would it lose on a cold day (50 F or 10 C) and only the top was above ground (25 Sq Feet.) Would ...
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### Does the temperature of water determine how much heat will be removed from air used to evaporate it?

This is a question about evaporative cooling as used in residential evaporative cooling appliances. This type of cooling uses the heat in the ambient outside air to evaporate water and remove the heat ...
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### Which air will give more effective cooling ? Dry or Moist?

Yesterday, I had an innovative idea. I live in India, and in summer season, the temperature can reach up to 45 degree Celsius. We use Split 1.5 Ton AC in our small office. The idea is to put an ...
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### Exception to weight of hot vs cold water?

I have seen the various posts regarding the comparison of weight of heated and cold water.But is there any contradiction?I live in really hot conditions and as such tap water literally 'boils' ...
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### Water Displacement in the Oceans As a result of Global Warming [duplicate]

Not sure if this is the right place to ask this but here goes. If the north pole ice sheets melt, everyone agrees this would be a bad thing, however one of the reasons they state for this being a bad ...
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### Would adding water after heating decrease the overall heat, when compared to adding the water before heating for the same period of time?

I was rather cold last night, and warmed up a cup of water to drink in the microwave. I put it in for 60 seconds, but it came out boiling hot, so I put a bit of cold water in with the hot water, and ...
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### Why does a water drop on a hot plate at $150^o C$ evaporate faster than on a plate at $200^o C$?

I recently read that: "A drop of water landing on a hot plate at $150^o C \:(300 F)$ evaporates in a few seconds. A drop of water landing on a hot plate at $200^o C \:(400 F)$ survives a whole ...
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### How come evaporation is possible? [duplicate]

If I have wet clothes and put them on the ground and let the Sun shine on them, they dry as water evaporates. But water should evaporate at 100 degrees Celsius so how come they go dry if it's just ...
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### Understanding how clouds form: warm air near the earth's surface?

I'm trying to understand how clouds are formed. I've read that it begins with air near the earth's surface heating up. But I'm hearing two different reasons for how this happens: Air pressure near ...
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### Does wrapping a wet paper towel around a glass bottle really speed up the cooling process?

There are claims like this one that you can improve the cooling speed of beverages when you put them wrapped in a wet paper towel inside the refrigerator/freezer. I've just tried it by myself and ...
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### Time for which a drop stays in the leidenfrost point

Is there any way to find out the time required for a drop of given dimensions to vaporize after attaining Leidenfrost point?
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### Could water physically makeup the core of a planet or otherwise large celestial mass?

Knowing very little about the nature of water, wondering how it might behave at the centre of a planet or centre of an another massive gravitational body. Could water take such pressures or might it ...
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### Building a magnetron powered steamer

I am wanting to build a microwave powered steamer for a reverse engineering project in university. I've read up some on this and know that its not as efficient as a heating element. I'm curious about ...
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### What is the equivalent of a eutectic point for a (two-liquid)+solids system?

I deal with complex phase equilibria involving solid and liquid phases at high temperature. Below is a simplified temperature-XH2O diagram for a multicomponent system at constant pressure. (Note: ...
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### Why does my kettle only make a noise when it is turned on

Almost as soon as I turn my kettle on it starts to make the familiar kettle noise, yet very shortly after turning off the power the boiling noise stops and the kettle is totally silent. The ...
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### Would sea water moderate a nuclear submarine meltdown?

My son asked me: If nuclear submarines get sunk or blown up, what is to stop them going into nuclear meltdown? I thought about it and came to the conclusion that because they're in the sea the ...
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### cooling glass of milk glass and a jar of water

When im given a steel glass of boiling milk which I cannot even touch, I used to put that glass in a jar surrounded with room-temp water and give it 10 mins. At the end, I used to find the steel glass ...
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### How does a canvas water bag cool water?

I was reading about this water bottle by Botl that behaves like a canvas water bags to keep water cool. I found out that this idea is an old idea and cars would drive with water bags in front as shown ...
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### Which one conducts heat better: water, or air?

If we were to assume room temperature of 20C, which of the fluids conducts heat better, and why?
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### Why does ice form on bridges even if the temperature is above freezing?

So with this "arctic blast" continuing, I've noticed that for my area, the temperature drops below freezing just long enough to cause freezing rain, but then the sun comes out and the temperature ...
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### Is the temperature different and or salinity different can lead to different colour of the water bodies?

I had skimming on an article about Thermocline and Halocline. How can two seas not mix? However, I am still curious on: Why the effect of Thermocline and Halocline are distinguishable based on ...
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### Can ice thickness be different on two nearby lakes?

In winter, is it possible for two distinct bodies of water, which are a few kilometers apart (so they are exposed to roughly same temperature), to have different thickness of ice? Does the area of the ...
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### How much heat needed to heat 400g of ice at 0°C to 20°C in a 200g aluminium pot? [closed]

An aluminium pot has a mass of 200g and contains 400g of ice at 0Â°C. How much heat would be needed to melt that ice and then raise the temperature of the resulting water to 20Â°C. The specific heat ...
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### 'Polar Vortex' Boiling Water to Snow is Mpemba Effect?

I am based far away from the icy storm currently blanketing the US - the 'polar vortex'. However, I have seen in the TV news footage of reporters throwing boiling water into the air, the water ...
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If water is cycled through a thin pipe by a pump, and a certain spot on that pump is made of thin copper that is being heated by a 1000 C source, will the water, as a whole, attain a heat of 1000 C ...
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### Compression and expansion

Why is it that solids on compression [As in striking a hammer etc.] heat up, but liquids and gases on compression [Pressurizing liquids causes them to freeze or gases to liquify] cool down? Can ...
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### How do I predict volume loss due to evaporation when boiling water?

Suppose I have a pot with diameter $D$ containing a volume of water $V$, being heated by a flame under it. If the ambient air temperature is $T$ and relative humidity is $R$, how can I calculate the ...
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### Is it possible to “cook” pasta at room temperature with low enough pressure?

It is known fact, that boiling point of water decreases by decreasing of pressure. So there is a pressure at which water boils at room temperature. Would it be possible to cook e.g. pasta at room ...
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### How to freeze the Niagara waterfalls?

Here is a picture of the usual vigorous Niagara Falls (in the winter). Here is the picture of Niagara Falls frozen in 1933 (in the very cold winter). Here is the picture of Niagara Falls frozen in ...
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### Why the dissolution of hydrophobic compounds decreases the entropy of water molecules in the vicinity of the solute?

The following is a quote from Lehninger's Principles of Biochemistry, 4th edition, pg.52: (...) dissolving hydrophobic compounds in water produces a measurable decrease in entropy. Water ...
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### How does a dehumidifier work?

I have read sites like this, but I am just not getting it yet. I'm looking to understand the variables involved, which I think are: air moisture content air flow (cfm?) condenser surface area? ...
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### How do you keep a fridge full of food cooler?

I just graduated and a mate moved into a flat (none of us are physicists by the way). So, were graduates, we got a new flat, and were broke. So, were now having a debate on how to keep a fridge ...
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### Is there an easy way to get water at roughly 70°C in our kitchen?

Some green tea requires to pour water at 70Â°C. I have no thermal sensor or kettle with adjustable temperature with me. Do you know a way to get water at roughly 70Â°C like â€œboil water and wait for x ...
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### Why does boiling water in the microwave make a cup of tea go weird?

When I boil water in the kettle, it makes a nice cup of tea. Sometimes I need to use a microwave because a kettle isn't available. I boil the water in the mug and it looks pretty normal, but when I ...
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### Would a small puddle of water evaporate faster if you spread a dry towel over it?

Let's say you spill 10ml of water on the kitchen counter. It forms a small puddle that would evaporate after a while (assuming room temperature and sane humidity). Would spreading a large, dry towel ...
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### How to heat swimming pool with physics principles [closed]

I'd like to apply physics principles to a home-experiment relating to my swimming pool. The water should flow inner to 100 meters of black pipe and so it should become warm. Then it should return in ...
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### Why does wet skin sunburn faster?

There is a popular belief that wet skin burns or tans faster. However, I've never heard a believable explanation of why this happens. The best explanation I've heard is that the water droplets on the ...
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### Is a tankless water heater more or less efficient than an electric stove at heating water?

Consider the following scenario that I actually encounter frequently: I just finished washing a pot in the sink, and now I want to boil some water for cooking noodles. If I fill the pot with hot ...
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### Time required for water to freeze

recently I was wondering if there is any specific formula in order to calculate how long it takes for certain liquids to freeze (especially water). I know this depends on: the volume of the liquid, ...
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### 1/2 freeze a water bottle

Is it possible to quick freeze half of an unopened bottle of water or soda by putting half of the bottle in a subfreezing solution liquid nitrogen or other solution without freezing the whole bottle?
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### Dissolving oxygen into water

I was wondering how one would actually calculate how much oxygen would dissolve into water given the necessary initial conditions, and what those initial conditions would need to be. I assume they ...
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### How to homegrow large, momocrystalline water ice crystals

This is a follow up to this question:Can one get clear ice crystals from a dirty suspension?. How could one grow a large - meaning visible with the naked eye - water ice crstal with common household ...