Tagged Questions
1
vote
1answer
41 views
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?
2
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2answers
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 ...
0
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1answer
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 ...
0
votes
1answer
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 ...
0
votes
1answer
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 ...
8
votes
1answer
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. ...
-1
votes
1answer
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 ...
3
votes
3answers
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?
14
votes
1answer
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 ...
0
votes
1answer
139 views
What is the ion drag mechanism in dielectric heating?
While reading about dielectric heating on Wikipedia, I read about the ion drag mechanism but there wasn't enough information about.
I know there is another Phys.SE question talking about the ion drag ...
4
votes
1answer
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:
...
1
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2answers
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.
...
1
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2answers
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 ...
3
votes
2answers
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 ...
3
votes
1answer
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 ...
2
votes
2answers
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 ...
2
votes
2answers
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 ...
6
votes
1answer
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 ...
1
vote
1answer
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 ...
5
votes
4answers
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 ...
1
vote
2answers
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 ...
4
votes
3answers
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?
2
votes
4answers
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 ...
0
votes
1answer
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 ...
0
votes
0answers
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 ...
2
votes
3answers
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 ...
2
votes
1answer
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?
1
vote
1answer
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 ...
3
votes
2answers
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.
2
votes
1answer
871 views
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, ...
4
votes
2answers
430 views
Why does a slight drip of water protect pipes from freezing?
I've heard that turning on faucets to a slight drip will prevent pipes from freezing, but I've never understood why this is the case. Can anyone out there help me to understand? Thanks!
1
vote
2answers
3k views
How does watering your plants help protect against freezing?
I've always heard that watering plants if the temperature goes a few degrees below freezing will help prevent them from freezing, but I've never quite understood the physics behind it. Can you guys ...
