# Tagged Questions

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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?
86 views

### Why is it faster (as in proportion to volume) to boil 4 cups of water than to boil 2 cups?

I did an experiment where I boiled two cups (500ml) of water in a kettle, and it took 1:30 minutes to reach around 98 C, average. However, when I boiled 4 cups of water, (1L) it only took me 2:30 ...
88 views

### Calculating the coefficient of thermal expansion in liquid

I am trying to write a matlab function that calculates the coefficient of thermal expansion of water from a given temperature. From what I understand the thermal expansion coefficient is calculated as ...
66 views

### Time constant of ice melt

I'm familiar with problems of "how much ice can you melt given some amount of energy", but I'm writing to get some clarification on the time constant of this event. This question might be somewhat ...
70 views

### Does electrically heated water have an adverse effect on hair?

I know I should have asked this question on a different site. but this was the most suitable site available right now for my question. Perhaps after this proposed site goes on Beta, we can move it ...
133 views

### What determines bubble locations in boiling water?

Something a little different to our usual fare. I was boiling a pan of water for cookery the other day, and got to wondering what caused the location of the bubble streams from the bottom of the pan. ...
107 views

### Sensible heat question (solving for temperature)

If $55 034.175 \rm{kJ }$ of heat are transferred to $150 \rm{kg}$ of ice at a temperature of $-12.15 ^\circ \rm{C}$, calculate the temperature of the resulting water. Using $Q = mc(t_2-t_1)$ or ...
332 views

### How can my water cool down more quickly?

I have a cup and I can only pour hot water inside, I wanna know whether the heat will dissipate more quickly with more water or less water? How about the occasion when my cup is well covered?
363 views

### Is there some way to narrow down the Leidenfrost point for water?

Cooks sometimes use the Leidenfrost effect to estimate the temperature of a frying pan by flicking a few drops of water onto the heated pan. I had no idea, before looking into this, that this could be ...
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139 views

### What would jumping into a pool and feeling cold be called? Conduction, or convection?

This was another question from my son's workbook. It said: ...
164 views

### How does blow-drying a mirror keep it from steaming up again?

After a hot shower, the mirror in my bathroom steams up. When I try to clear it with a towel, it immediately refogs. Yet once I use my hair-dryer, it will clear the fog and the mirror will stay clear. ...
376 views

### Why can't I evaporate water without wind, just heat? (not boiling,evaporating!) Or can I?

So here is the thing, I searched all over the internet for this but all the sources say that I need wind because the process of evaporation goes as follow: Water particles at the top layer with ...
251 views

### Why does it take until the middle of summer before lakes have warm water, but desert sand heats up in hours?

My sister asked me this question and I keep thinking that water would conduct heat much faster than sand. Hence the energy transfer of heat across the lake does not allow it to heat up soon. Sand on ...
500 views

### Calculating time to heat cold water in bowl of hot water

How would I calculate the time it takes to heat a given volume of water to a given temperature with a given temperature T1 when it is submerged in a volume of water with a temperature T2 Estimation ...
333 views

### Why water will stay on a piece of toilet paper?

I think everyone has tried to blow air (breath) on toilet papers. The papers will get wet. I believe the holes diameters on a toilet paper should be much larger than diameters of water molecules. (The ...
1k views

### Why I will feel colder when I get out from a swimming pool?

A friend of mine told me that because water heat capacity is higher. He also mentioned that it was similar to alcohol on skin effect. Assume that there are 3 situations. 1. I did not get wet 2. I got ...
352 views

### Microwave oven + water: dielectric heating or ion drag?

When you place a water or food in a microwave oven, it heats. Which process commits more energy to that: dielectric heating, or ion drag i.e. resistive heating? AFAIK, in distilled water (which is a ...
715 views

### How much disolved oxygen is removed by boiling water?

Apologies if this is a chemistry question I've read that drinking water contains dissolved oxygen to the tune of $10\:\rm{ppm}$. I've also read that raising the temperature of water will remove some ...
664 views

### Sauna thermodynamics

Why does it get hotter (feel hotter) in a sauna when one pours water over the hot stones? Wikipedia says that the water condenses onto the skin, but the actual air humidity is so low that I doubt ...
1k views

### Microwaves vs Gas or Electric Coil heating of a water boiler in a typical household

Wouldn't it be more energy efficient and or safe to use microwaves to heat our home's water boiler instead of using dangerous gas or hot electric coils that could catch other things on fire? I'm kinda ...
1k views

### Why does hot oil explode when pouring water on it?

I am puzzled to know, What is the reason of hot oil make sound and explode when we pouring water on it?
983 views

### Which is more efficient, heating water in microwave or electric stove?

So our propane tank in the kitchen ran out again today. Which is more energy efficient, boiling water in a microwave on an electric stove? All things being equal i.e. starting temperature and mass ...
303 views

### Temperature change effected by electric heater [closed]

A 40-gallon electric water heater has a 10kW heating element. What will the water temperature be after 15 min of heating if the start temp is 50F degrees. There must be an equation. I can't find it ...
1k views

### How to determine size of a Heat Exchanger?

I am designing a Tube heat-exchanger, similar to this: My process requires water (at room temperature, 18C ~ 22C) that is being pumped out of a small tank (300 Liters) to be heated in a ...
962 views

### Does stirring water in a bucket in whirlpool keeps it warm?

I did an experiment when I was a teenager. I want to prove/see what really went on in that experiment. When taking a bath, take a warm water in bucket and start taking a bath. You will notice that ...
232 views

### Why does blowing on someone who is wet feel colder than on someone who is dry?

The title says it all. If I'm standing in the wind and I'm wet, I feel much colder than when I'm dry. This is true no matter how warm or cold the water. Why is this?
507 views

### How does liquid convert to gas on getting thermal heat energy?

Say for example, when we heat, water converts to steam gas. How does it happen? What happens underneath giving rise to breaking of bond between molecules in liquid state and spreading them in gas ...
255 views

### Will the water added to an ice piece freeze?

Water, at room temperature is poured into a hole made of a block of melting ice(kept at room temperature).I was wondering if the water will ever freeze? Thank you.
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### Simple formula for liquid heat transfer

I'm trying to do a simple simulation of a solar panel coupled through some piping to a boiler, with the aid of a pump. My input constants could be something like: volume of liquid inside the panel, ...