What is Cooling: Definition and 638 Discussions

http://www.cnn.com/2011/WORLD/asiapcf/02/01/koreas.talks/index.html?hpt=T2 It appears that however they end up doing it, talks to not, the situation on the Korean Peninsula is being mutually de-escalated. For the time being, I would say this is a good development, if only so that focus can...

Sorry about posting my pointless crap, I just wonder a lot about things lol. I realize the cooling system is pressurized to keep the coolant from boiling, but what if you never see over 190F, ever. Would the pressurized cap have any benefit in that case? Someone told me once about how...

Homework Statement A small metal bar, whose initial temperature was 20 degrees C is dropped into a large container of boiling water. How long will it take the bar to reach 90 degrees C if it is known that its temperature increases 2 degrees in 1 second. How long will it take the bar to reach...

I am currently working on a project that cools water moving through a chilled aluminum block. I am not familiar with the math/physics involved and would like some direction or recommendations. My project is currently setup so that I suction 32oz of 70 degree F water out of tank1 and pump it...

What happens if you cool the mixture of water vapor and air to the temperature lower than 273 K? Since saturation pressure is higher than 0 some vapor should stay in the air. In the solid form?

Homework Statement Moist air at 40 C and 90% R.H. enters a dehumidifyer at the rate of 300 m3/min. The condensate and the saturated air exit at 10oC through separate exits. The pressure remains constant at 100 kPa. Determine (a) the mass flow rate of dry air, (b) the water removal rate, and...

Homework Statement How does the average rate of cooling relate to saturation of salt in water? Variable: salt, water, surface area of pot/container, initial temp The Attempt at a Solution So, to do this lab I started out with saturated water, and then got progressively less saturated...

quickly cooling substances... :confused: I'm on a project using peltier cells, and i know that there are some cells that can freeze water in 20 seconds... My question is, is there any substance that can freeze as quickly as the peltier cell or just freeze quickly? I just need a substance or...

Homework Statement First a glass of milk is put outside the refidgerator to heat, and its temperature changes from 6 degrees C to 13 C after two hours. When the temperature of the milk is 15 C the glass is put inside a refridgerator. the problem is to find the ambient temperature in a...

Hi All, Would someone explain why the stratosphere is cooler than the ground? Thank you, Bob

Homework Statement An object of temperature 60oF is placed in a medium maintained at a constant temperature moF. At the end of 5 mins thetemperature of the object is 45 oF and after another 5 mins its temperature is 36 oF. Find m Homework Equations y=cekt+m The Attempt at a...

Homework Statement 1 mole of Hydrogen gas at 300 Kevin is contained in a thin walled copper container. In container #2 there is 1 mole of Neon gas also at 300 Kevin. The volume= 22.4 liters and surface area ,A = .476 m^2 The surroundings are at 100 deg Kelvin. The specific heat of H2= 5...

Homework Statement 1 mole of Hydrogen gas at 300 Kelvin is in a thin walled copper container vol 22.4 liters surface area A = .476 M^2 In vessel #2 , 1 mole of Neon gas also 300 Kevin The specific heat of H2= 5 cal/mole (K) Thermal conductivity (k) H2 = .0433 cal/sec. converts to .00866...

I am looking to create a cooling system for my xbox 360, what I intend to do is have 4 fans in a set up underneath the console and once it becomes above room temperature the fans switch on and then once it drops to, or below room temperature the fans turn off. I understand for this I will need...

I am not sure if this is the correct place to post, but here goes. I have to do an experiment on liquid cooling, using 2 types of liquid cooling blocks, one fin based, one channel based. The liquid used is water, and the pumping system is the same. The cooling blocks are attached to a...

Homework Statement Newton's Law of Cooling states that the rate of cooling of an object is proportional to the temperature difference between the object and its surroundings. Suppose t is time, T is the temperature of the object, and Ts is the surrounding temperature. The following...

Homework Statement What's the formula that better describes the temperature as a function of time for an enclosed body of water with certain initial temperature T_a immersed in another body of water of initial temperature T_b? More clearly, I performed an experiment in which I put a...

Homework Statement Suppose that the temperature of a pan of warm water obeys Newton's law of cooling. The water (47 degrees Celsius) was put in a room and 10 minutes later the water's temperature was 40 degrees Celsius. After another 10 minutes, the temperature of the water was 34 degrees...

MTd2 spotted this interesting paper by Florian Conrady (Perimeter postdoc). To go with this paper the author has provided two animations to watch: http://www.florianconrady.com/simulations.html The second one of these two simulations ("Model with 2D interactions") shows the crystalization of...

Homework Statement A copper sphere of radius d is put inside walls very close to 0K. The initial temperature of the sphere is T_0. The surface of the sphere is totally black and we assume it loses energy only due to radiation. 1)Find an expression for the time passed till the temperature...

Hi All: My question is, why do some nuclear power plants have cooling towers and some don't? Why spend extra money on cooling towers if the feedwater can be cooled by the large body of water such as lake? Thanks!

Hello. I live in a house which has 4 bed rooms on second floor and living room and kitchen are on the first floor. The house has a central heating/cooling system. At the last night my roommate asked me to open all doors on each room including bath rooms when I leave the house. She thinks...

Homework Statement A man was murdered and inspectors found his body temperature to be 88 degrees at 4:30AM. Climate control in the room was set to 76 degrees. Temperature of his body was taken again 2 hours later and found to be 85.8 degrees. The standard body temperature for human...

This is an interesting subject. There have been discovered very large (up to around 100 kpc) hot (10^7 K) intergalactic gas clouds within galaxy clusters. A simple calculation based on the density of the gas clouds in question and the emission rate of the hot gas shows the gas clouds should...

Hey. I've been trying to find a really small, micro water pump, direct current, in-line 2.5"x1.5" maybe slightly bigger, but preferably tubular in shape and as small as possible. Looked on ebay to no avail. Any ideas? It has to be cheap as well, something under $50. Oh and 1-2 GPH flow...

Homework Statement Newton's law of cooling says that the rate at which the emperature of any object changes is proportional to the temperature difference between the object and its surroundings. So if the temperature of the object is T, and its surroundings are at a constant temperature...

Anyone have any experience with cooling a telescope mirror for image quality improvement? I have my C11 disassembled for some other upgrades and before putting it back together am considering adding a cooling fan. Anyone have opinions on how big of a difference it can make?

please let me know how to cool the junction of thermocouple... is it possible to give current to both the wires n get junction cooled...?

I'm somewhat familiar with the formula: T(t)=T_{0}+(T_{i}-T_{0})e^{kt} However, what if the ambient temperature is not constant? How would one find the temperature of an object with an ambient temperature that ramps from A to B (steady ramp let's say)? I'm honestly not sure how to...

Hi, I have a graph of T-TR vs. Time. These values were given to us for an assignment. However, the question then says using these values, "show" that it obeys Newton's Law of Cooling. I can't ask my teacher because it's meant to be done on your own but show means many things to me. Does...

Hello everyone, i have my HTPC inside cupboard, thus when stressed it overheats. on top of the cupboard i have some slits, and i wanted to build a cooling unit to circulate the air inside. i thought of using there fans...

I have received an assignment which requires me to build a device that can cool two liters of water (at room temperature) as much as possible. The only source of energy is me; I can drive the device in whatever way I can. I am allowed to run the device for 30 minutes, and the lowest temperature...

Newton's Law of Cooling (diff eq. -- separation of variables) Homework Statement Fresh coffee sitting in a room cooling...you know the routine. Anyhow T(0) = 90degreesCelcius. Room temp=25degrees Celcius find k. Then he asks us to use Euler's method to estimate coffee temp after five...

Simple question. Am I right in thinking that, according to current theory, the rapid cooling occurring after the Big Bang is a direct result of the universal spatial expansion (absurd as it may seem), for the following two reasons. 1) as the (hot) particles of matter move into that new...

Hey all, I am working on a 0-40V variable power supply right now, and while the power supply is working I am wondering if it is in danger of overheating. I am using a LM317 with a 0-5k potentiometer between adjust and ground, and a 165ohm resistor between output and adjust. Input is regulated...

When the heat gets transferred to one side and the other side gets cold , what causes this cooling effect , why does the heat go from one side to the other on the different metals , does this have something to do with the electrons.

Homework Statement A lava beds cool very slowly, remaining warm for years. Calculate the rate of heat conduction per square metre through a 30 m thickness of rhyolite, if the surface is 400 degrees celcius and its interior side is at 3100 degrees celcius. The thermal conductivity of rhyolite...

I was thinking about Newton's cooling law, which was originally derived empirically, and is often described as an empirical law. Usually when something is defined as a physical law, it means that it is derived from observation of the world around us, and cannot be derived from more fundamental...

Hey guys was hoping someone could give me a hint for the derivation of Newton's Law of cooling stated in the following equation form:http://img263.imageshack.us/img263/3143/a6e5a27835e9e5738016606.png http://img716.imageshack.us/img716/8728/75784887.jpg Thanks in advance!

Hi Clever People, I've been watching an amazing program about dark matter, dark energy and dark flow. I thought there were questions that should have been asked, but then I'm a website designer - what do I know! So... as an interested non-physicist, my apologies if this question is...

Why is it that when you heat an object, it takes longer compared to cooling it?

Hey everybody, this is not exactly a homework question, but I am writing a term paper on the topic of laser trapping and cooling, and would appreciate any good sources that anyone could provide. This is an undergraduate thermal physics class, and does not need to be extremely technical...

I have an application where I need to calculate the vacuum (pressure change below atmospheric) generated from a cooling liquid in a semi-rigid container. If the container is filled near full (e.g. 2 litres) with a liquid at e.g. 70C, sealed and left to cool to ambient (e.g. 20C) there is a...

When going through topics on melting and freezing, i came across 2 graphs of slightly different curvature for both the heating and cooling of naphthalene. The ending part of the graphs are the ones that confuse me, whether slope upwards or downwards. Most graphs in the internet just show...

Homework Statement A thermometer is removed from a room where the air temperature is 20degree C and is taken outside where the temp is -10degree C. After 1 minute the thermometer reading is 3degree C. What is its reading after 3 minutes? Homework Equations The Attempt at a Solution...

Homework Statement Hello i am doing a cooling experiment and i want to know the following: y=28.49e^(-0.03890*800) +26.51 (note the 26.51) is not part of the exponential. What is y? and I was wondering whether this would go ever go through the x axis? Thanks people! Homework...

A friend of mine brought his laptop to me today after it started acting funny, turned out to be over heating problem, since then and I'm thinking.. Why don't they make a cube/container and place the processor in it with liquid Nitrogen around it? Wouldn't that keep it cool forever? I'm not a...

I read it in my book that Newton's law of cooling can be derived from Stefan's law. Is it possible, and if so, how?

Newton's Law of Cooling (not the formal definition): (change in time) = -ln ((Tf - S)/(Ti - S)) / k Tf = final temperature Ti = initial temperature S = temperature of environment k = heat transfer coefficient Say that you wanted to cool something (such as a person) to a negative...

hello all, We live in a hot part of the world with the extra bonus of high humidity - around 90%. We don't have A/C, and don't really want to get it (energy use). Evaporative cooling won't do much (towel on head) becuase of water saturation in air. Would a cold wet towel + fan force water...