Evaporation Definition and 205 Threads

With the theory of Hawking Radiation, people generally say to imagine that the black hole has a temperature, so it must radiate heat. But, this really is not how it is said to work. The means by which the black hole evaporates is not that particles are actually coming out of it, or that it is...

black holes evaporate, i know that it sounds like it defies all rational elucidation but i think that black holes evaporate. see black holes emmit black body radiation they also emmit hawking radiation and hawking radiation as far as I am informed shrinks black holes it causes them to lose mass...

Feet first... How do I calculate heat loss by evaporation from the surface of a swimming pool, at a range of temperatures and given a range of conditions? Any help gratefully received! Nick

The moderators here decided my explanation of evaporation was wrong, but they failed to explain why. They simply said I was an idiot and locked my thread. So... I ask the gods of physics here that moderate this board: How does evaporation work at the molecular level? Say you have a body...

Hi everyone This is my first post, please be kind! I am part of a research group at Oxford University, UK. We are investigating ways to make multicrystalline Si solar cells more efficient. One of the characterisation techniques we use is electron beam induced conductivity (EBIC)...

I am new to this site and would like to find some equations for water evaporation? I would like to understand more fully how placing water in a vacuum effects the rates at which it will evaporate? Any help would be greatly appreciated

I am new to this site and would like to find some equations for water evaporation? I would like to understand more fully how placing water in a vacuum effects the rates at which it will evaporate? Any help would be greatly appreciated

Thinking about this, I would say that there really is no difference. When water evaporates, surface molecules gain enough kinetic energy to change state (if it even makes sense to talk about state in the thermodynamic sense when dealing with discrete molecules). During boiling, you are giving...

My sister and I are working on a project in which we need to know the rate of evaporation of water... I know that there are a lot of variables to this equation, but we aren't sure exactly where we will end up completing it, so does anyone know a formula to calculate the evaporation rate of...

I am curious. Maybe I don't understand something, but many articles I come across perform an energy balance on a solid and on a liquid. **I assume evaporation acts on the remaining liquid and not directly on the substrate. Correct?** They always include heat loss due to evaporation as...

Dear all, I have a quite easy plan: W want to evaporate a gold circuit on a Brass plate. Between this copper and gold I need to make an isolating layer to prevent short-currents. i thought to make this layer of Silicon-oxide. Is the possible to evaporate and what source can I use this for...

Homework Statement A) How much energy is required to evaporate all the water in a swimming pool of area 119 m2 and depth 2.4 m on a typical summer day? (Please note that the temperature of the water in the lake stays the same.) (For latent heat of vaporization use 2200 kJ/kg.) B) The...

I have a question about evaporation of organic solvents and the leftover sample after this is done. (sample dissolved in the organic solvent) Does the sample, leftover after the evaporation of a organic solvent, (used to dissolve the sample) affect the analysis of the dry sample? (basically...

The question: If you fill a shallow dish with water at room temperature the water will, under normal conditions, evaporate completely. It is easy to believe that some of the more energetic molecules can escape from the water surface but how can all of them eventually escape? Many of them do...

Hi, we are running experiments with solar power; any inputs on below problem are highly appreciated. TNX Robby Project: We are experimenting how to maximize evaporation, using Solar Power. We have set up parabolic dishes with a fixed focus (Scheffler Reflectors). Each reflector can...

This thread is about a Bill Unruh article ("Where are the particles created...?") and an article on the same theme by Unruh and Ralf Schützhold ( http://arxiv.org/abs/0804.1686 "Origin of particles in BH evaporation") and Schützhold's participation in the LQG-BH workshop taking place this month...

Hi, I'm now studying evaporation and condensation and I have a question. Why even when water boils, its temperature doesn't exceed 100 C? Where did the energy gotten from environment go? What was it used for? Examining structure of water and vapour molecules are given as a hint, but I see no...

For stirred, maintaining temperature at 80 and at atm pressure thx ..

To whom it may concern I'm a University of Portsmouth student in the UK and have a conundrum for one of my projects. I'm trying to evaporate a reservoir of water at the bottom of a venting system to cool down the airflow in a gap between two membranes for a period of time. The reservoir is...

Homework Statement The rate of evaporation of a spherical drop of liquid is proportional to its surface area. Derive R(t) assuming constant density, where R(t) is the radius of the drop as a function of time. Homework Equations I know that the surface area of the sphere is A = 4 \pi...

If a salt crystal forms after 3 days of evaporation, and the crystal mass is 30 mg, how many Na+ and Cl- ions was added to the crystal each second (average). How do I solve this?

An interesting equation derived from Classical General Relativity: Solar evaporation time: \boxed{t_{ev} = \frac{ m_{\odot} c^2}{P_{\odot}}} m_{\odot} = 1.98892 \cdot 10^{30} \; \text{kg} - Solar mass P_{\odot} = 3.846 \cdot 10^{26} \; \text{W} - Solar Luminosity \boxed{t_{ev} = 1.473...

Two vessels of the same volume, in the same location and open to the atmosphere. One is tall and of a small diameter, the other is short and is of a larger diameter. Each vessel supplied with an identical heat source. Each vessel filled with an equal volume of an identical liquid. The goal...

And if I'm heating a liquid that contains things that evaporate at different temperatures, will I have an increasing amount of trouble separating these things as I increase the amount of heat applied?

I am trying to calculate the rate (g/m2) of water evaporation given Temperature, Humidity, Air Speed, elevation. The best source of an equation for this I have found is from engineeringtoolbox.com, but I have found a possible error in their calculation. (I am in a far off land with no access...

Not sure where this posts needs to go, as I am not familiar with engineering, so if it needs moved, please do so. I build decorative ponds, and one of the conversations I end up with is the evaporation rate of the water in a pond setting. I do know there are formulas out there on the rate of...

in classical electromagnetic a charge can make energy. Now consider Howking radiation effect: if an anti-particle fall into the BH the volume of BH will reduce. But if that particle be a charged particle, this charge can make positive energy and increase the volume. Is that right?

If it is indeed true that black holes (eventually) evaporate, then once they lose enough mass do they then return to become a normal body of matter? I would assume that once this happens there would be an enormous explosion due to constraints of relativity disappearing.

Someone asked me what happens when micro-black holes evaporate, and I have no idea, not really knowing anything about the theory of black holes, other than what you learn in a first course in GR. What he was asking was whether the black hole just keeps emitting energy (in the form of Hawking...

Hey guys, I was wondering if anyone could help me out with this problem? If you place 10.0L of methanol (CH4O) in a sealed room that is 3 m long, 1.75 m wide, and 2.5 m high, will all the methanol evaporate? If some liquid remains, how much will there be? The vapor pressure of methanol is...

entropy increases? entropy decreases ? no change in entropy? diffusion, evaporating, mixing, melting, separation i think diffusion - increase evaporation - increase mixing - increase melting - increase but what about separation :S? and if anyone thinks any others are...

I've got a problem. I'm trying to design a reactor with internal cooling provided by water flowing through tubes directly within the reactor. Basically, it's like a shell and tube heat exchanger with an internal heat source. The problem is that the cooling water is to be evaporated within...

The latent heat of vaporization of H2O at body temperature (37.0°C) is 2.38E+6 J/kg. To cool the body of a 71.9 kg jogger [average specific heat capacity = 3550 J/(kg*°C)] by 1.10°C, how many kilograms of water in the form of sweat have to be evaporated? Q=cmt Q=mL...

I've been trying to discover a qualitative description of Hawking Radiation and Black Hole evaporation and haven't been able to find one yet. I figured this board might offer some insight. Can someone explain to me how a 'virtual' pair differs from a 'real' pair? It seems to me that no...

According to the Black Hole evaporation theory, Hawking Radiation is emitted from the black hole. My first question is: Does it emit in one single direction or at polar opposites, and my second is: What happens when enough matter is emmited, does the black hole suddenly become visible again...

When you jog, most of the food energy you burn above your basal metabolic rate (BMR) ends up as internal energy that would raise your body temperature if it were not eliminated. The evaporation of perspiration is the primary mechanism for eliminating this energy. Determine the amount of water...

Hi, I've been wonderring what happens to a substance once boiling point is reached, in particular the rate of evaporation. Am I right in thinking that further energy will cause the rate of evaporation to increase, while temperature of substance remains constant? Is there a point where if...

Could someone link me up with some information, either text or web based, concerning evaporation rate of water, in a slightly reduced pressure environment. I need to design a settling tank for a vacuum system to separate a fine oxide powder from water. We produce the slurry at a rate of about...

I guess this would go under chemistry. At least I leared what thermodynamics I know from my chem class. Here's the situation: My dad wants to know if the decreacing water level in the jacuzzi is due to a leak or evaporation. The pool guy told us to fill up a bucket with water and compare...

I know that the conventional explanation for this is that the water needs energy to evaporate so it conviniantly takes the heat energy from your body in order to do this. But first of all, why does the water need to evaporate in the first place? Because of the sun? Then it should be getting...

Hi guys I am slightly confuse about a statement in the kinetic explanation for evaporation as well as melting. Firstly for the evaporation: "Thus the latent heat supplied in causing evaporation represents the potential energy gain of the escaping molecules plus the work needed to expand...

I am in my first year of the IB Diploma and I have chosen Higher Physics and want to do my extended essay in Physics. Is fluid dynamics (or fluid mechanics i.e. how things fall in water and why) better or is analyzing the effect of colors on the rate of evaporation better? This essay has to be...

Hey. If i jump out of a swimming pool, into a breeze, i feel cold. Is this because the breeze is moving the more moist air away from my body, allowing more evaporation to occur, cooling the water, and since two substances of different temperatures naturally want to equalize in temperature...

my biggest problem is the word problems. i can't figure out how to write the equation so that i can do the math... Heat is escaping at a constant rate (dQ/dt is constant) through the walls of a long cylindrical pipe. Find the temperature T at a distance r from the axis of the cylinder if the...

A few days ago i took a test on heat and temperature ect. One of the questions was : When we say evaporation is a cooling process, we are saying that: a. surrounding air is cool b. the liquid is cooled. I chose a. because i knew that evaporation draws in energy from air to evaporate cooling the...

Does anyone know the most usual unit for evaporation speed? Is it kg/(m2*s)?

Evaporation and Condensation... If 58 grams of hot water at 71°C is poured into a cavity in a very large block of ice at 0°C, what will be the final temperature of the water in the cavity? in °C How much ice must melt in order to cool the hot water down to this temperature? in grams is...

this seems to be an interesting paper, though I can't tell for sure (don't understand the idea of naked singularity well enough, how you can have one) http://arxiv.org/abs/gr-qc/0506129 Quantum evaporation of a naked singularity Rituparno Goswami, Pankaj S. Joshi, Parampreet Singh 4...

Any takers approximating evaporation rate?! I am trying to estimate the rate of water loss from a 13'L x 6'W x 6'D mixing container at room temperature under a 12 inches of mercury vacuum. There is constant mixing of the fluid (dirty water). There is 180 cfm air movement through the top of...

http://arxiv.org/abs/gr-qc/0504029 Black hole evaporation: A paradigm Abhay Ashtekar, Martin Bojowald 18 pages, 4 figures IGPG04/8-4, AEI-2004-072 "A paradigm describing black hole evaporation in non-perturbative quantum gravity is developed by combining two sets of detailed results...