All Questions
Tagged with enthalpy or thermodynamics
15,737 questions
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What are the arguments towards the Life-and-Entropy relation?
I've heard it from a few people, and I've seen it popup here in the site a couple of times. There seems to be speculation (and studies?) towards this idea, and this is what I've picked up so far:
...
- 5,121
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What is the difference between thermodynamics and statistical mechanics?
What is the difference between thermodynamics and statistical mechanics?
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How does mass leave the body when you lose weight?
When your body burns calories and you lose weight, obviously mass is leaving your body. In what form does it leave? In other words, what is the physical process by which the body loses weight when ...
- 1,355
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Experiments that measure the time a gas takes to reach equilibrium
If you take two ideal gases at different temperatures, and allow them to share energy through heat, they'll eventually reach a thermodynamic equilibrium state that has higher entropy than the original....
- 5,121
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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!
- 3,759
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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 ...
- 3,759
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How cold does it need to be for spit to freeze before hitting the ground?
What is the dominant form of heat transfer between warm water and cold air?
If a $100 mg$ drop of water falls through $-40 C$ air, how quickly could it freeze?
Is it credible that in very cold ...
- 53.7k
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Is there an equation for convective heat transfer?
Is there an equation I can use to calculate the temperature (as a function of time) of an object which is gaining or losing heat by convection? Or equivalently, the rate of energy transfer from the ...
- 77.3k
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Is there a number that describes a gas's departure from the ideal gas law?
When judging if relativity is important in a given phenomenon, we might examine the number $v/c$, with $v$ a typical velocity of the object. If this number is near one, relativity is important. In ...
- 53.7k
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How does the temperature of the triple point of water depend on gravitational acceleration?
Suppose I do two experiments to find the triple point of water, one in zero-g and one on Earth. On Earth, water in the liquid or solid phase has less gravitational potential per unit mass than water ...
- 53.7k
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Why are materials that are better at conducting electricity also proportionately better at conducting heat?
It seems like among the electrical conductors there's a relationship between the ability to conduct heat as well as electricity. Eg: Copper is better than aluminum at conducting both electricity and ...
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How efficient is a desktop computer?
As I understand it (and admittedly it's a weak grasp), a computer processes information irreversibly (AND gates, for example), and therefore has some minimum entropy increase associated with its ...
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What cools a drink?
When you stick ice in a drink, AFAICT (the last physics I took was in high school) two things cool the drink:The ice, being cooler than the drink, gets heat transferred to it from the drink (Newton's ...
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Why does adding solutes to pure water lower the the specific heat?
We found that water with salt, sugar, or baking soda dissolved in it cools faster than pure water.
Water has a very high specific heat; how do these solutes lower it?
We heated a beaker (300ml) of ...
- 159
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How long does it take an iceberg to melt in the ocean?
This is a quantitative question. The problem is inspired by this event:
On August 5, 2010, an enormous chunk of ice, roughly 97 square miles (251 square kilometers) in size, broke off the Petermann ...
- 2,717
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Irreversible expansion and time reversal symmetry
Suppose there are N non-interacting classical particles in a box, so their state can be described by the $\{\mathbf{x}_i(t), \mathbf{p}_i(t) \}$. If the particles are initially at the left of the box, ...
- 4,931
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Why is there no absolute maximum temperature?
If temperature makes particles vibrate faster, and movement is limited by the speed of light, then I would assume that temperature must be limited as well.
Why is there no limit?
- 1,465
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Why doesn't air freeze?
I am in no way experienced in the Physics field so this question may seem a bit silly but i'd appreciate an answer :)
Why doesn't air freeze?
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Ice skating, how does it really work?
Some textbooks I came across, and a homework assignment I had to do several years ago, suggested that the reason we can skate on ice is the peculiar $p(T)$-curve of the ice-water boundary. The ...
- 15k
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1
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What kind of systems of black holes satisfy the laws of black hole thermodynamics?
I've come across black holes thermodynamics multiple times recently (both at this site and elsewhere) and some things started bugging me.
For one thing, first law bothers me a little. It is a ...
- 23.8k
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how to calculate gibbs free energy per unit mass, per unit volume, and per mole?
I've ran into conflicting information on how to calculate the Gibbs free energy of fuels during combustion per unit mass, volume and mole.
A sample solution for hydrogen would be really appreciated!
- 191
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CPT and heat equation
I haven't understood this thing: Physics is invariant for CPT trasform...But the Heat or diffusive equation $\nabla^2 T=\partial_t T$ is not invariant for time reversal...but it's P invariant..So CPT ...
- 1,434
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How efficient is an electric heater?
How efficient is an electric heater?
My guess: greater than 95%. Possibly even 99%. I say this because most energy is converted into heat; some is converted into light and kinetic energy, and ...
- 3,227
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2nd Law of Thermodynamics
I understand that the 2nd law of thermodynamics roughly states that, if you have a body (or a gas in a chamber) that is hot at one end and cold on the other, the heat will always flow from the hot to ...
- 2,446
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A water drop in vacuum
Let's imagine the following situation:
At an initial moment $t=0$, a large water drop with diameter for example $D=10\ \text{cm}$ is placed in deep space (Say an astronaut is experimenting). Let's ...
- 2,717
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Home experiment to estimate Avogadro's number?
How to get an approximation of Avogadro or Boltzmann constant through experimental means accessible by an hobbyist ?
- 11.1k
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Why do lightbulbs continue to glow after the light is turned off?
I've noticed that whenever I turn the lamp off in my room at night, the lightbulb seems to continue to glow for a minute or so after that. It's not bright though; the only way I even notice it is if ...
Whitney
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How to estimate condensation from air?
How to estimate the amount of water condensing from air on a surface, given the air's temperature and relative humidity and how they change over time, the surface temperature, material's thermal ...
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Maxwell's Demon Constant (Information-Energy equivalence)
New Scientist article: Summon a 'demon' to turn information into energy
The speed of light c converts between space and time and also appears in $E=mc^2$.
Maxwell's Demon can turn information ...
- 411
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What causes hot things to glow, and at what temperature?
I have an electric stove, and when I turn it on and turn off the lights, I notice the stove glowing.
However, as I turn down the temperature, it eventually goes away completely. Is there a cut-off ...
- 6,030
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Why does evenly heating soup with a microwave take so long?
My anecdotal observations (which could be incorrect, they're totally unscientific) indicate that it takes almost as long to evenly heat a big bowl of soup in a microwave as it does to heat it on the ...
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Would wearing clothing that is black on the inside and white on the outside keep you cooler?
The Straight Dope ran an explanation of why nomads often wear black clothing - it absorbs heat better from the body. On the other hand, white clothing reflects sunlight better. Is it possible to get ...
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Intuitively, why is a reversible process one in which the system is always at equilibrium?
A process is reversible if and only if it's always at equilibrium during the process. Why?
I have heard several specific example of this, such as adding weight gradually to a piston to compress the ...
- 53.7k
4
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Law for tap water temperature
I was wondering if anyone put together a law to describe the rising temperature of the water coming out of a tap.
The setup is fairly simple: there's a water tank at temperature T, a metal tube of ...
- 13.7k
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What will happen if we add salt to boiling water?
I would like to have a good understanding of what is happening when you add salt to boiling water.
My understanding is that the boiling point will be higher, thus lengthening the process (obtaining ...
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