Heat Definition and 1000 Threads

Hello! I am not sure I understand how the heat from the lasers get dissipated in LIGO, at the mirrors. Given the high power of the lasers, the mirrors heat up, but the setup is in vacuum, so it is difficult to get rid of that heat. How do they make sure that the mirrors don't get too much damage...

Cooling water inlet temp is 4 degrees C Cooling water outlet temp is 80 degrees C Density of water is 1000 kgm-3 Specific heat water is 4.2kJkg-1K-1 Density wort is 1060 kgm-3 Specific heat wort is 4.0Kjkg-1K-1 Overall heat transfer coeff is 3000Wm-2k-1 Area of each plate is 0.75m2 For water...

Hello, I am a Mechanical Engineer a little out of practice on Heat transfer. I am trying to solve this problem. It must be solvable but i have yet to find right equations online. I have a multi Layer Cylinder made up of C350 marraging Steel,Zinc Alloy-12 , then 6061 Aluminum T6. All that is...

Hi all, I have a copper pipe which has 15mm of insulation on it. The outside radius of the pipe is 17.2mm and the inside radius is 14.8mm. The insulation will have a conductivity of 0.025. I found an question which is meant to show an equation for the heat loss in an Insulated Cylinder or...

Watching the Australian Open and they use a heat stress rating to protect the players. I've searched for the details of how it is calculated without success. Anyone know the formula that they use? Just curious.

If ##N## is constant (per the partial derivatives definitions/ the subscripts after the derivatives) then ##G## is constant ##H - TS = constant## Taking the derivative of both sides with respect to ##T## while holding ##N,P## constant we get the following with the use of the product rule...

Q=heat capacity calorimeter*(-)change in T*moles =0.009089mol*-6.8C*4.38kj/C =-0.2707kj/mol This answer is wrong but it was the only one I could come up with right now. I just noticed units in the answer would be wrong too. Any suggestions?

When designing a panel, it is imperative that you keep the components inside at a temperature which they can operate optimally at; allowing the air temperature to go above this limit can cause component failure and fire. To assist with calculating the air flow required to keep the components...

My attempt: I though : ΔQ_w= 1*4200 * (-100) J=-420000J Q_ice=334000*m_ice = ΔQ_w But it was totaly wrong! The solution showed : Because the heat engine is reversible the efficiency η = 1- (T_cold / T) T_cold is always 273 K while the hot temperature changes from 373 K to 273 K during this...

this is my attempt of a solution , but my only equation is should i convert Θ to Celsius , and if i did the specific heat of the other substance is greater , how is that if its inversely proportional with temperature ! . and the other Θ is 200 K so it should be less ?!

Hi, I am solving the radially symmetric heat equation with an internal heat source(this is meant to model the heating of a cylindrical battery). It's meant to model heat in a cylinder with conduction to the environment, so my outer boundary condition is Newton's law of cooling. The $T$ in the...

Hello guys. I am studying the heat equation in polar coordinates $$ u_t=k(u_{rr}+\frac{1}{r}u_r+\frac{1}{r^2}u_{\theta\theta}) $$ via separation of variables. $$u(r,\theta,t)=T(t)R(r)\Theta(\theta)$$ which gives the ODEs $$T''+k \lambda^2 T=0$$ $$r^2R''+rR+(\lambda^2 r^2-\mu^2)R=0$$...

In collisions that are inelastic or partially elastic, how can we predict how much of the energy lost to the surroundings becomes heat, and how much becomes sound? What determines that fraction?

This is a past exam paper Q. I think i might be missing info though. For i) i use q=UAdT A= 35m2 dT= (80-20) They haven't given U but if i know answer should be 1,050W So if i set U to 0.5 (0.5)(35)(60) = 1050W Am i missing something or could I calculate U with the info given? Also ii) Use...

We consider a system composed of liquid helium in equilibrium with its vapor at very low temperature T, each phase being considered extensive. We neglect the mass of the gas compared to that of the liquid, as well as the heat capacities of the gas and the walls compared to that of the liquid...

Can anyone please guide me in what I'm missing to answer part b)i? I can't seem to work out the thermal conductivity (k) in order to find the heat transfer by conduction? Or is the different approach that I must take to do this question? Thanks for any help!

Here is the Q below I want to see if my values for part b) is okay? This is what I have tried: Any help would be nice! Thanks

In heat engine we define a heat source from where heat is transferred to the system, we say that heat source has a temperature ##T_h## , When we define a Carnot heat engine, the first process we have is an isothermal expansion and we say heat has to come in system through this process and here...

I attached below my attempt to solve the question.

Here's my attempt for the first part: For the first body, the work obtained is ##W_1 = C_P (T_1 - T_f)## while for the second body, it is ##W_2 = C_P(T_2 - T_f).## So the net work obtained is the sum of these two: ##W = W_1 + W_2 = C_P (T_1 + T_2 - 2 T_f)## and that proves the first part...

I'm not sure if this should be here or under Earth Sciences. GHGs warm the atmosphere, but they do that largely in response to LWR from the heated surface. The relative contributions of the major GHGs are known, but I can't seem to find anything about the contribution from surface heat. For...

Which material or combination of materials is the most highly conductive(super-conductor) and highly reflective and heat resistant at the same time? I am asking this because I am trying to block radiation. T

Here's a picture of what I tried. I was wondering if this is correct?

The first picture was provided along the problem statement. The second has my annotations. I initially began by calculating the ratio of efficiencies, since the work done is obviously the same and cancels out, but after failing and having seen the form of the solution I saw that that cannot...

Here is the Q below This is what I have tried so far. I ended up getting a value of 1772.4 watts Is this the correct way of doing this problem?

Can anyone please help me on how to tackle this question? I really do not have any clue to make a start on it? Thanks for any help!

I) Area = 3.14 x L xD 3.14 x 60 x 0.11 = 20.72m2 Q=UADT = (1.0Wm2k-1)(20.72m2)(150-20) = 2693.6 W Changed flow rate from 0.1kgs-1 to 360kghr-1 II) Enthalpic Capacity in dry steam = steam flow rate x latent heat vaporisation Q=mDh = 360 x 2114 (formula looks for lat heat vap but we have latent...

Hi, I was revisiting my (high school level) understanding of thermodynamic cycles and I think I still have some doubts. Last year and more recently I posted a few questions which surely helped me, but I think I need more clarifications. In a nutshell, what I'd like to know is the following...

I think the C_V for van der waals gas will be larger than ideal gas since it‘s a more precise description. However, for the relationship I cannot come up with a specific equation.

Hi I'm going to use a light based source of heating for a science experiment at my university and I'm a bit confused. Sometimes the names infrared (IR) lamp and heat lamp are used as two different thing and sometimes not but I can't find clear info about it. Is there a difference? thanks in...

Hi, I was just wondering about the efficiency of a cycle that is not Carnot cycle. In that case one should use \eta = 1-\left|\frac{Q_{\rm out}}{Q_{\rm in}}\right|, where Q_{\rm in} and Q_{\rm out} are the amounts of heat absorbed and released during the cycle. For instance, I guess that in...

I am operating via finite differences. Say for example, I have this pipe that contains a fluid. I have the boundary condition at x = x1: k is the effective thermal conductivity of the fluid, T is the temperature of the fluid at any point x, hw is the wall heat transfer coefficient, and Tw is...

I do not know where I am doing wrong. I asked a tutor, he said I was doing it correctly. Below is my work. Please help! Net loss by radiation in 10.0 mins is 74.8 kJ

I find that $$U=\int Z \epsilon D(\epsilon) e^{-\epsilon β}d\epsilon=\frac{gV}{(2\pi)^3}\int Z \frac{(\hbar)^2k^2}{2m}k^2 (4\pi)e^{-β\frac{(\hbar)^2k^2}{2m}}dk$$ where g=2s+1=2, $$Z=e^{βµ}$$ and $$D(\epsilon)=\frac{gV}{(2\pi)^3}k^2 4\pi$$ for the density of states From here, I can use $$c_v...

(In opening, hi. I'm a lawyer, not a physicist, and I'm entirely out of my depth here.) I need to make roughly 8 wooden frames (19 inches x 1-1/16 inches x 9-1/8 inches). Into each, I'd like to place a thin metal plate with hexagonal cells (5.27 mm cell diameter) pressed into them. I need to...

Can I derive heat capacity of one phase mixture of three liquids as a sum of their mass shares multiplied by heat capacities of solitary components at given temperature? All components are miscible, of course ... thank you in advance

what will be the joules per meter using thermal gain and wattage gain from a solar cell if the cell is in an insulative vacuum not counting the thermal degredation of 25% for wattage loss due to heat gain

I took my car to the shop and they had it for 3 straight weeks even changed the spark plugs but they never could figure out what was wrong with it. Now that it's getting cooler weather it's taking bout 2 hours of having the hair dryer blowing on the back of the engine for it yo start up, does...

Hello, I have a question with regard to equipment design. How do I calculate the overall heat transfer coefficient for a large pipe who has smaller pipes in it? Say I have water flowing on the large pipe, and inside it there are three pipes with hot acid in them. Assuming they flow concurrently...

So first I transformed the equation no 2 like this: $$|Q_L|=K\cdot|W|$$ And then I transformed the first equation to find ##|Q_Z|## $$|Q_L|=|Q_H|-|W|$$ Plugging the result into the first equation $$|Q_H|=K\cdot |W|+|W|$$ $$|Q_H|=|W|\cdot (K+1)$$ We know that the efficiency coefficient K is...

I'm trying to find a heat transfer equation that includes time. Metal tank, partially filled with liquid. I need to find the time it would take for the temperature on the outside of the tank to drop from θ2 to θ1, given thickness, metal and liquid's properties, and tank dimensions

Hi! Came across this forum while researching my project, and this seems like a good place to ask. Thanks in advance! I'm building a hot tub that will use a 55 gallon steel drum wood stove as a heat source. The drum is built into one of the sides so that the majority of the stove is surrounded...

Hi, If it is assumed the temperature of a shower is to be 43°C and the electric shower consumes 50 litres of water at that temperature, then the Energy required for an electric shower would be: QElectric Shower = mcΔT QElectric Shower = 50 * 4.181 * (43-10) QElectric Shower = 6.89945 kJ or...

Not attempt

Hello All, I am working on a project with plate heat exchangers connected in a cascade system to heat up water connections in a huge system The Problem Statement : A boiler produces and circulates hot water at 65 degC to a Heat Exchanger and come out at 50 degC, where as the other fluid is...

How should I do to eliminate the error message? In what direction should I approach the question? (I have tried difference combination and sequences of the heat exchanger below pinch, all seems not working) Thanks

This is how I solved part a) : ##Q_1=C\cdot (T_1-T_i)## This quantity is negative because object 1 loses heat. (positive for the machine) ##Q_2=C\cdot (T_2-T_i)## This one is positive because the object 2 absorbs heat.(negative for the machine) Then the exchanged heat FOR THE MACHINE is...

Hi, I don't understand why the author in calculating the expression for the specific heat, divides by ##1/V## (the total volume). Also, in calculating the fraction of modes with frequency in the range ##v##, ##v+dv## he divides by ##V## (eq. 2.65, 2.67) Thanks, Ric

I am working on some simulations to determine pressures for extremely high-pressure combustion events. The temperatures in these events can range anywhere from 3000 K to 6000 K. In order to do this I need to find valuers for specific heats of gases at these temp ranges as I know they vary to a...

What is the origin of the fact that heat flows from hot to cold? Does it have something to do with fluctuations?