What is Cooling: Definition and 639 Discussions

What caused the universe, specifically the Earth, to cool after the big bang? Was it because of the space expansion and thus the relationship between wavelength and energy (as wavelength increases E drops?) or what? A basic answer is good =] Thanks.

any suggestion on the most efficient method to cool water from 25C to 10C . the volume of the water is 1 cubic meter...? thank you

Homework Statement At 1:00 PM, a thermometer reading 70 degrees F is taken outside where the temperature is -10 degrees F (ten below zero). At 1:02PM, the reading is 26 degrees. At 1:05PM the thermometer is taken back indoors, where the air is at 70 degrees F. What is the temperature reading...

Hi, Please explain me about the Secondary Cooling Unit (SCU)-Aerospace? Please explain its functionality?

What materials can be used for the piping in liquid sodium cooling loops (primary and secondary) and for the heat exchanger?

at 1 pm, a thermometer reading 70 F is taken outside where the air temperature is -10F (ten below zero). at 1:02 p.m., the reading is 26F. At 1:05 p., the thermometer is taken back indoors , where the air is at 70 F. What is the temperature reading at 1:09 pm? Ive made a table like this...

Homework Statement 5 kg of lead shot at 97.9 °C are poured into 5 kg of water at 26.0 °C. Find the final temperature of the mixture. Use cwater = 4187 [(J)/(kg·° C)] and clead = 128 [(J)/(kg·° C)]. Homework Equations The Attempt at a Solution How do I start this?

Homework Statement A smaller bowl of porridge served at 200 degres F cools to 160 degres in 1 min. What tempature (too cold) will this porridge be when the bowl of exercise 27 has reached 120 degres F (just right)? Homework Equations y(prime)(t)=k((y(t)-T sub a ) y(t)=Ae^(kt)+T sub a...

Homework Statement A roast turkey is taken from an oven when its temperature has reached 185 degrees F and is placed on a table in a room where the temperature is 75 degrees F. When will the turkey have cooled to 100 degrees F? Homework Equations dT/dt=k(T-Ts) where Ts=temperature of...

Hi Physics forum, I have a pipe which is of length L, inner diameter D. It is packed with CO2 at pressure P (assume it's still a gas with none of this funny supercritical business!) and temperature T. The density of the CO2 is rho and the joule-kelvin coefficient is mu. the pipe is initially...

Homework Statement The time it takes for a deceased human body to reach room temperature. Room temperature = 25 degrees C Initial temperature of corpse = 37 degrees C Homework Equations I used Newton's law of cooling: \frac{dT}{dt} = -k(T - T_{room}) where T is a function of t(time in...

Hi. I'm looking for a easy way of using heat to create cooling. I am trying to make a device that will use the heat from one place, to cool something in another place down. Maybe this is more for the engineer forum, but what I need to know first of all is the names of the processes. For the...

By passing warm air through a cotton sock acting as a wick immersed in water, how can I calculate the maximum evaporation to achieve the gratest temperature drop in the air flow? What is the typical formula for temperature drop in evaporative cooling models?

Hi, I don't fully understand this thing. I've read it on wiki, but it just doesn't get through. Perhaps I am a dumbass. I've 3 questions that hopefully will help clear it up. 1) How do you stop adiabatic cooling? 2) In a closed and insulated system where there is a compressed gas...

I would like to model a cooling sphere, losing heat at the boundary through radiation. Is there a book that can help me?

So everyone knows about this method of making ice cream, cooling drinks, w/e. You add salt to ice and it lowers the freezing/melting point and this cools things below 0C. I understand why the freezing point is lowered and all that but I don't understand why this cools things down faster. So...

I am aware that absolute zero can not be achieved by cooling a substance since absolute zero is zero-point energy. I was just wondering what is used (coolant wise and apparatus wise) to cool something near this temperature since there some experiments such as the Boise-Einstein Condensates which...

Homework Statement "A cup of hot chocolate, in a room temperature of 21*C, cools accordiing to Newton's law of cooling. Determine the rate of cooling, k, of the hot chocolate if it cools from 86*C to 65*C in 15 minutes" Homework Equations Newton's cooling law, ln function T-Ts=(T. -...

I've seen it before that some people say that global warming will cause or does now cause areas to greatly cool as well. How is this true?

Hey, I'm having problems with this question: According to Newton's law of cooling, what cools faster, a person from 150 degress celcius to 100 degrees celcius or 100 degrees celcius to 50 degrees celcius in a laboratory environment? Why? I' not really sure where to start. I know the...

Ok hi guys, recently i was doing a practical on thermodynamics. Then i came across of a question which was to comment on the assumption that the rate of heat loss for 2 different liquids , placed in identical calorimetry copper cups was the same.( the 2 liquids started off at the same...

Ok hi guys, recently i was doing a practical on thermodynamics. Then i came across of a question which was to comment on the assumption that the rate of heat loss for 2 different liquids , placed in identical calorimetry copper cups was the same.( the 2 liquids started off at the same...

Homework Statement Bob loves vegetarian pizza. How long will it take Bob's pizza to cool to 110 degrees if he bakes it at 450 degrees for 20 minutes? The temperature in his house is a balmy 70 degrees. Homework Equations T(t) = Ts + Do*e^(-k*t) where... Do = initial temperature...

Hi! My Physics introductory book states the following: "A dew point is a state defined by the temperature to which the air has to be cooled isobarically (with constant absolute humidity) for the vapour to become saturated." Humidity is defined as m/V, where m is weight of the vapour, V is...

I really have no Idea where to start... Please help Homework Statement A monatomic gas is cooled by 50 C at constant volume by removing 830 J of energy. How many moles of the gas is in the sample. Homework Equations ?Q=mc (delta)T The Attempt at a Solution I am not sure...

I have a problem where I have an air cooled condensing unit located in a large room within a building. The volume of the room is approximately 27,195 cubic feet. The air cooled condensing unit rejects 102,600 btu/hr to the space. Assuming the ambient air temperature of the space is 95 degrees...

I am trying to relate an object temperature as a function of time using Stefan's Law. Newton's law of cooling is, \frac{dT}{dt}\; =\; k\left( T-R \right) Where T is temp, t is time, k is a constant, and R is the temperature of the surroundings. Stefan's Law is, P\; =\; e\sigma AT^{4}...

I have a question about Newton's Law of cooling. Basically I understand that the equation, http://album6.snapandshare.com/3936/45466/853596.jpg Comes from the DE, dT/dt = K(T-To) Using this, I am to solve this problem: A thermometer is taken from an inside room to the outside, where...

When a valve on a pneumatic tire (filled with compressed air) is released and the tire is allowed to deflate, one may notice that the valve stem will become quite cold during the process. A common, everyday observation. So far, so good. The question is: What would we observe if the tire being...

Here is the situation: We have 100w heatload coming from little die which has only 1cm^2 of surface area. We cool it with Ln2 as cold as possible (in normal atmospheric pressure) by using simple round container which is made of 99.99% copper. Let's assume that system is perfectly isolated so all...

Hello, I am currently engaged in an High School chemistry project. I was wondering if you guys could help me out. The project itself is not required to be related to chemistry at all; it can be a physics/biology project as well. After some brainstorming, I have narrowed my topic down to...

Right now, we're doing thermal physics. For one of our assignments, the teacher asked us to make our own experiment and write on a lab on it. For this lab, we had to investigate a question she gave us: If water is left in a container open to the air, its temperature will drop below the...

Please move to appropriate forum if necessary. I need some help. Attached is a pic of my standard 1/4hp Hayward pool pump. I want to enclose it to make it quieter. (The sound is being transmitted by air rather than by physical contact.) As a "proof of concept" I stuffed it in a storage bin...

Sir, It is said that a hollow sphere cools faster that a solid sphere. Is it because a hollow sphere contains smaller quantity of heat than the solid sphere? Or is it because the rate of heat loss is inversely proportional to thickness of the conductor through which heat is lost?

At my company, we have a design using thermoelectric cooling. I have no idea how they work, is there some phenomenon i don't know about?

Sir, Can you state an example for forced convection loss? Is Newton’s law of cooling also applicable to forced convection losses apart from natural convection losses?

Hello, I am an undergrad student studying Physics. We are currently studying thermodynamics. The lecturer has set us a bunch of problems relating to Thermodynamics. While I can do most of them, I am getting completely thrown by one question: An object with a surface area of 0.2 m², an...

Hi folks, I recently posted about one facet of a bizarre argument I've (stupidly) involved myself in in the solid state forum. Perhaps someone can help me out with the entropy side of things here. Basically, the guy I'm speaking to has some bizarre ideas about a way to use a (single, or...

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...

In a cooling curve of a single substance there is a thermal arrest point where the liquid turns into solid. My laboratory manual mentions that in a cooling curve containing two liquids (A + B), in addition to the arrest there is a second point called a "break". It says the point at which solid A...

Hey Folks, I was showing my students Newton's Law of cooling (precalc class) and one of my students pointed out that this doesn't really model the cooling of an object, he said that he had recently learned in chemistry that the temperature of the object that is cooling actually dips down...

Why do people try to get the lowest temperature possible on their CPU? Is the sole reason because as temperature decreases electrical resistance decreases, meaning less collisions of electrons, and then therefore less heat from kinetic energy? Would the limit of cooling the CPU be at zero...

I have a question about Accoustic Cooling. I know that most Aerosol Cans under Pressure of a low boiling point Fluid will get very cold when shaken vigorously. Has there ever been an experiment were a Super Conductor was impregnated with micro bubbles of a Cooling Liquid, where when the...

I have this one problem dealing with Newton's law of cooling: \frac{{dT}}{{dt}} = - k(T - A) I'm basically trying to determine at what time someone died! The info I have is that at time of death, the temperature was 98.6 degrees, at 10 AM it was at 92 degrees, and at 2PM it was at 86 degrees...

ok, i have forgotten my thermodynamics, and need a confirmation for my thoughts here...if youd compress He gas by blowing more gas into a thermo-isolated tank, the tank would get hotter right? and after compressing it enough the gas will become fluid (thats not a real phase transition, but you...

I'm having trouble thinking of an instance when Newton's law of cooling is no longer valid. could it have something to do with the surface of the system or the surroundings not having uniform temperature. thanks very much

A ventilationsystem is to cool 60,000 m3/h of air. The outside air is 26C at 60% RH, after cooling it is down to 14C. The evaporative temp. is 6C. How do I use the h-x diagram to find the need for cooling, I suppose in kW?

If one has a cooling fan that uses 6 kW, does that automatically mean that the room receives 6 kW worth of heat?

I need some help with this ladder diagram that is for a cooling system. Here is the assignment: The system has two rooms that need to be cooled. There is one evaporator in each room with one fan. The evaporators should have an electric anti-ice system (heat rods) that is to be controlled by a...

A cooling system for a fridge at a store has a cooling effect of 35 kW. I'm having a bit of trouble understanding what this actually tells me, iow what it means. Could someone explain it in some easy manner...? When someone says that there is a cooling need for 35kW, I don't really get it. If...