All Questions

Tagged with
Filter by
Sorted by
Tagged with
0
votes
3answers
28 views

Warm or cold air

Which air can be used to dry out food or clothes? Warm or cold air? I've read that keeping food in the fridge makes it dry out. Blowing hot air to the hair also dries the hair out. I'm confused.
0
votes
0answers
24 views

The Refractive Index of Water after Several Heating and Cooling Cycles

If the refractive index of water under a certain temperature, say 20 degreeC, is 1.33334. Will it return to exact the same value after one or several heating and cooling cycles? Or will it shift a ...
2
votes
2answers
44 views

How long does it take to cool down a drink with ice?

If I have a bottle or container with X fluid ounces of water at temperature Y (say, fridge temperature or room temperature), and I put ice or ice sticks (composed of water) in it that make up Z fluid ...
0
votes
1answer
46 views

How does an ultrasonic humidifier / atomizer affect temperature?

Evaporative cooling is a technique used to cool air by using the evaporation of a liquid. My google research on evaporative cooling shows a ubiquitous concept of forcing air through a pad/membrane/...
10
votes
3answers
1k views

Does tea made with boiling water cool faster than tea made with boiled (but still hot) water?

I always make tea with boiling water - not water that is almost boiling, not water that has boiled and stopped boiling a few seconds earlier - in my opinion, for the best tea flavour the water must be ...
-1
votes
2answers
87 views

How many calories of energy does it take to heat up 1 cubic inch of water 1 degree Fahrenheit? [closed]

In metric, one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade--which is 1 percent of the difference between ...
1
vote
1answer
72 views

Is the triple point of water exactly 0.01 $\deg$C?

Is the triple point of water exactly $0.01 \deg$C, or is this an empirical value/is there some uncertainty to it? If so, how do we know it is exact, and why?
0
votes
2answers
106 views

Which one is better to boil water, using high heat or less heat?

Consider that I have a water boiling kettle as below. Assume that it is made of metal, not plastic (but plastic probably also will do). Assuming I can adjust the power it uses to boil the water with ...
2
votes
3answers
60 views

water pipes break when temperature goes down, how to estimate the energy involved?

Normally low temperature is associated with lower energy state and high temperature with higher energy state. There is an apparent paradox when a water pipe breaks due to low temperature: when ...
2
votes
5answers
97 views

In thermal spas the temperature of steam is about $50^{\circ}C$, but feels way hotter. Why?

So when you're in hot water and start to move or something the steam feels really hot even though I read its temperature is about 50 degrees Celsius in thermal spas. So why does it feel that warm?
-1
votes
1answer
62 views

why does cold water have Translucent visibility? [closed]

If ice is to formed soon, why ice Does not have Tranparent vision.
5
votes
2answers
3k views

At what pressure will water boil at room temperature and why?

Is there a specific pressure that is needed to boil water at room temperature? If there is, what is it? Why does water boil at a low pressure at all?
0
votes
0answers
43 views

When we mix water with H$_2$SiF$_6$ and boil them, how much of the H$_2$SiF$_6$ evaporates?

If water evaporates also at temperatures much lower then its boiling point, and so do, I believe, other liquids, how much H$_2$SiF$_6$ (boiling temp. 108 C) is to be found in the steam over boiling ...
-1
votes
1answer
447 views

Final temperature of ice and water [closed]

My answer doesn't seem likely but I can't see where I've gone wrong: Q: Ice of mass 0.125kg at -5 degrees is added to water of mass 0.25kg at 8 degrees. Calculate the final temperature of the water ...
1
vote
3answers
1k views

Why can I touch hot things longer with water on hands?

So I have done a couple of personal experiments with water on my hands. One day I was taking bread (rolls to be exact) out of the oven with my bare hands and burned my hands when my hands were dry. ...
0
votes
1answer
94 views

Determining friction force while stirring water

So I researched a bit on this, and found a video which showed an experiment in which he boiled the water, just by pouring it into a high-speed blender and stirring it. Can someone tell me how can I ...
80
votes
6answers
20k views

Why does water stop boiling immediately after turning off the heat?

When I am heating water on a gas stove, it begins to boil after some time and bubbles of air can be seen escaping out. However, as soon as I increase the amount of heat in the stove, the rate of ...
4
votes
7answers
196 views

Is it possible to prevent water from cooling by keeping it in an rigid container?

If you fill a soft plastic water bottle with hot water, close the lid, then cool the water down, the bottle will contract. When you open it up, it will expand again. Conversely, if you used a hard ...
5
votes
1answer
172 views

How do I calculate how long water will take to warm from 22°C to 35°C?

I'm a microbiologist and my physics is not up to par for figuring this out. I've requested our engineering department to perform a temperature mapping of the vessel, but they can't do it for me. I ...
-1
votes
2answers
50 views

What is the equation relating the mass of water and its temperature change in a fixed time?

I heated up a beaker of water to 70˚C and set a time of 2 minutes. I measured the change in temperature in that time interval. I changed the mass of water and measured the change in temperature each ...
6
votes
1answer
150 views

Water molecules on the Sun? How does that work?

I've been reading about water on the Sun. The water they talk about is supposedly in a gaseous state because the Sun is so hot. But I'm wondering how even that could exist. Wouldn't the extreme ...
1
vote
1answer
528 views

Boiling potatoes

If the temperature of boiling water is about 100 ºC (depending on air pressure), why are boiled potatoes on a high stove flame cooked faster? From the English Wikipedia: Acrylamide was discovered ...
3
votes
4answers
3k views

Does salt affect the boiling time of water?

If I have 1 cup of water on the stove and another cup of water with a teaspoon of salt. would the salt change the boiling time of the water?
2
votes
1answer
442 views

Why is steam-cooking slower at higher altitudes, where water boils at a lower temperature?

This question comes from a chemistry test that i got back. I'm posting this on physics.stackexchange because i feel that i don't get the physics side of it. We learned that temperature increases the ...
0
votes
2answers
97 views

Must gaseous water be 100C (or greater) regardless of pressure?

I know that if you evaporate a molecule of water, that it must be 100C in order to be gaseous, so that it will take that heat with it if it wasn't already that temperature. This has a cooling effect ...
2
votes
2answers
15k views

Water pressure vs temperature

If I have a sealed enclosure full of water (constant volume) at 25˚C at atmospheric pressure, I then heat the water to 50˚C. Would the pressure in the sealed enclosure change? If the pressure has ...
3
votes
1answer
137 views

How warm are rain drops?

I thought of this question after a week of jogging, where each day after it rained, the temperature seemed warmer. I also noted this as a lifeguard where, after closing the pool due to thunder, we ...
0
votes
2answers
60 views

Water not turning into ice until brought into warmer temperature

I left a water bottle in the freezer for it to cool since it was warm, so I could drink it sooner. After a couple hours I forgot I put it in there, so I opened the freezer, and to my surprise it was ...
3
votes
1answer
65 views

Fully understanding the effects of specific heat

I have yet to find a source that adequately explains our reasoning behind why we describe something as "hot" and something as "cold". Textbooks describe the water as something that is less hot than ...
1
vote
1answer
276 views

Water dripping from handheld shower head loop

I've got a shower head attached to the wall by a long metal covered flexible hose. The shower head stays attached to the wall so there is a long loop of hose hanging down between the wall and the ...
1
vote
0answers
63 views

Does pure water freeze at the same temperature even if there are a mix of gases in the environment?

For example water has a triple point at 670 Pa c.ca.at 0.01°C Could she freeze at this temperature even if there is another gas in the mixture of the vapour,for example He4 at 1Atm? Does the Rault law ...
1
vote
1answer
1k views

What is the temperature of water vapour itself?

Assuming standard atmospheric pressure, Does the water vapour created from boiling water have the temp of 100 °C? What about water vapour created by evaporation at room temperature?
0
votes
2answers
229 views

Why does drying off with a towel at room temperature not feel cold?

I thought that if you're wet, a breeze will feel cold because the water moisture is evaporating and whisking away heat along with it. With a towel at room temperature (same temperature as a breeze), ...
1
vote
1answer
611 views

Boiling of Water

I studied in textbooks that the boiling point of water is the temperature at which the vapor pressure is equal to the atmospheric presssure. My doubt is since the vapor mixes with atmosphere, how can ...
2
votes
1answer
551 views

How does relative humidity affect the rate of water evaporation?

How does the relative humidity of the air affect the speed at which water evaporates? I know there are other parameters that affect it, so I made this assumptions: We have a plain metal plate of $1m^...
7
votes
1answer
229 views

Specific heat capacity vs KE gain of particles

To increase the temperature of 1kg of water by 1C you need 4200J of energy. However, the KE gain is only $\frac{3}{2} k_B \Delta T \cdot 6.02\cdot 10^{23} \cdot \frac{1000}{18} = 692.3$J. Where does ...
0
votes
1answer
29 views

How to construct a more efficient cooler made by cheap materials to cool a glass bottle containing hot water without pouring the water out?

details -limitations:it can only use five blocks of ice and the cooler must consist one container to put the glass bottle.Also,cannot interfere the water in the glass bottle such as to stir it. but ...
0
votes
3answers
1k views

Is the boiling point of water really 100°C? If so, how come water evaporates at lower temperatures? [duplicate]

I had this doubt since so many years. Suppose you pour water on the floor. Then you switch on the ceiling fan and select stage 5 on its regulator. Then the water on the floor evaporates without ...
5
votes
4answers
4k views

Temperature of steam rising off boiling water

When boiling water on a stove, will the temperature of the steam vary significantly with the temperature of the burner? Person A's argument: So, once individual water molecules reach 100C/212F, they ...
0
votes
3answers
822 views

Can water vaporize without reaching 100 degrees celsius? [duplicate]

I think many of you just let water sit somewhere outside, on a surface it can not be absorbed in. What happened to the water? Did it vaporize? Can water still vaporize if it is not on 100 degrees ...
3
votes
2answers
6k views

Why does a wet towel become more hot than a dry one?

I remember a long time ago my mum had told me not to use a wet tea towel when taking food out of the oven because you can burn your hands - lo and behold, it came time to make dinner and I did not ...
0
votes
1answer
122 views

what will the buckets water temperature? [closed]

Suppose there are 2 buckets.. say Bucket A and Bucket B. Both contains 20 liters of water and both are at same temperature. A person took 2 liters of water from A and 4 liters from B. He boils both ...
2
votes
1answer
414 views

Finding atmospheric pressure using temperature of boiling water

I was checking the temperature inside my oven using a multimeter with a temperature probe. I had set the oven's thermostat to 190o C, and it had reached equilibrium, but the measured temperature was ...
0
votes
3answers
1k views

Why does blowing air over hot wet surface makes it dry faster?

After removing the boiled water from a hot kettle, which is wet, the water evaporates rapidly if air is blown over it. What is the science behind this phenomenon?
24
votes
1answer
871 views

Freeze water in red-hot container

While reading Edgar Allan Poe's short story The thousand-and-second tale of Scheherazade (about a fantastic journey to the present of 1850) I once stumbled on the following footnote to the phrase "...
4
votes
0answers
1k views

Why water heat capacity has minimum at body temperature?

Water heat capacity has the following plot: One can see it has minimum near 40 degrees of Celsius, i.e. close to human body and other warm blooded animals have. Is this just coincidence? UPDATE ...
3
votes
2answers
1k views

Do foods with water exceed 100° celsius in the oven?

I was thinking that water in liquid state can't normally be much above 100 degrees celsius because it boils, so probably foods with lots of water like vegetables don't warm more than 100 degrees. Does ...
2
votes
2answers
2k views

How can I boil water at a temperature less than 100 degree Celcius?

I need to boil a water-based solution at a temperature lower than 100C. What kind of liquid should i add to the water to make this happen?
4
votes
1answer
333 views

How does my car antifreeze work (in thermodynamic terms)? Freezing point depression

Water freezes at 0$^{\circ}$ C, ethylene glycol freezes at -12$^{\circ}$ C, but my car starts at -20$^{\circ}$ C. Mixing them together prevents my car engine's coolant from freezing down to -30$^{\...
0
votes
2answers
127 views

How much water did I actually drink? [closed]

Water expands at temperatures over $5^\circ\mathrm C$ strictly monotonic. If you now drink $1~\mathrm{L}$ water ($5^\circ\mathrm C$) which will expand in your body on $37^\circ\mathrm C$, did you ...