Heat Definition and 1000 Threads

Q1=2.5(390)(90-30) =58500 Q2=2.5(4000) = 10000 Qtotal = 58500+10000 Q=68500 =6.8x10^4 my teacher sent this as a homework but the options were 4.9x10^4 J 1x10^4 J 6.8x10^5 J 5.9x10^4 J im confused is is this a typo or did i do something wrong

Q1 = m(ice) * Cv * ∆T = amount of heat the ice absorbs Q2 = m(H2O) * Lf = amount of heat the water loses Q1 = (4*8 g) * (2198 J/g*K) * (0-(-15)) = 1.055 * 10^6 J Q1=Q2 Q2 = 1.055 * 10^6 J = m(H2O) * Lf Lf = 1.055 * 10^6 J / m(H2O) = 1.055 * 10^6 J / (0.25 L * 1000 g/1L) = 4220 J/g My answer is...

I have tried to solve this with these equations: COP=T(H)/( T(H)-T(L) ) and COP = Q(H)/ ( Q(H)-Q(L) ) But since I need both Q and T in the same equation, I can't find anything to solve it.

Hi, the approximate (not accounting for plate size and separation distance) formula for heat flux exchanged via radiation between two parallel plates is: $$q=\frac{\sigma (T_{1}^{4}-T_{2}^{4})}{\frac{1}{\varepsilon_{1}}+\frac{1}{\varepsilon_{2}}-1}$$ where: ##\sigma## - Stefan-Boltzmann...

For a course project, I need to design a heat exchanger to cool electronic components in an UAV. The heat exchanger will be cross-flow air to liquid. The cold side (air side) properties are evaluated at an altitude of 7620 m and -34.5 °C. For the hot side ethylene glycol - water solution with a...

The Second Law of Thermodynamics is not an easy topic. However, if you understand the concept of direction of thermodynamic processes and heat engines, you w...

I'm solving the heat equation on a ring of radius ##R##. The ring is parameterised by ##s##, the arc-length from the 3 o'clock position. Using separation of variables I have found the general solution to be: $$U(s,t) = S(s)T(t) = (A\cos(\lambda s)+B\sin(\lambda s))*\exp(-\lambda^2 kt)$$...

First of all, I didn't know whether to pick this subforum or the engineering/compsci one, I understand this might need to be moved to a more appropriate subforum. The general approach is fairly obvious, use implicit method to construct the tridiagonal matrix for Thomas method and solve. However...

Hi guys, I am confused about the heat transfer mode of between two contacting material, especially in a channel flow. Obviously, conduction or convection dominate the heat transfer process in the process with low object temperature . But I am not sure if I have a fluid of 500 Kelvin, flowing...

Hello, I am doing a study for my final years Uni project, which includes waste heat recovery from gas fuelled engine exhaust. I am using a data sheet for a Jenbacher J620 engine-. In the data sheet it is stated that; exhaust gas mass flow (wet) = 17325 kg hr ( not sure about the wet part?)...

Good evening everybody. I am new here I hope it is okay to ask this question here. As part of a project I am trying to examine the effect of a pulsating laminar duct flow on the heat transfer behavior for constant heat flux at the wall for a Newtonian incompressible fluid. As such I am...

I'm thinking about that for 1 hour. But, I could not do it.

How to modify this Formula? and arrive at the solution. Q = -K(Th-Tc)A/thickness

The intensity is proportional to the square of the distance between the source and the body and also depends on the angle of incident. I = The intensity at 0° (Assuming I = some constant) then I0 = I cos(Theta) Theta = the angle of incidence. I want to solve this using trignomentry. Is it...

Hey all, I am working on a problem that goes like this: The cargo space of a refrigerated truck whose inner dimensions are 12 m 3 2.3 m 3 3.5 m is to be precooled from 25°C to an average temperature of 5°C. The construc- tion of the truck is such that a transmission heat gain occurs at a rate...

I have two bodies, one at a higher temperature say 1000°C (Body A) and the other is at 22°C (Body B). Body A emits Radiation (Surface to Surface interaction). The temperature of Body A is maintained by a constant supply of Energy. The Body B will absorb the Radiation Energy from Body A, and its...

There's an undergraduate physics course at my uni that covers these topics and the course description is: Mathematical descriptions for classical physics: oscillations, mechanical waves, electromagnetic waves, physical optics and thermodynamics. Are there any good studying materials/textbooks I...

Can water simply absord the kinetic energy from colliding air molucules to change its phase? And can water transformed into ice simply have the kinetic energy of its molecules increased to balance out the lost latent heat? Would not this again change ice into water?

Here is one scenario: I have placed a metal in my room which is at room temperature. Air has little much heat capacity and metals don't like to store heat. Would heat transfer occur? Whatif I set the temperature of both to a certain degree where it crosses heat capacity of metal but not of air?

I tried to created it but i dknt know how to even start

First, I calculated the heat required for the ice to melt: Q=mLf Q=0.150×330 Q=49.5 J Then, I calculated the final temperature of the water by forming the following equation: Q=mcΔT −49.5=(0.15+0.35)×4200×(Tf −80) Tf=80.0 degrees Celcius But the answer says 32 degrees Celsius.

Please and thank you!

I guess, firstly I have to calculate the heat that is needed. Q=c*m(t2-t1) I'm not sure what to do further from here.

I've been messing with the Q = cm(t2-t1)=cmΔt formula If I change it to m=Q/(c*Δt) everything is fine until I reach the c part, because there has been given the c of ice and the c of water too, do I just subtract c ice from c water?

I need help solving this please. Its a past exam paper. requires wort to undergo 5% by mass evaporation in one hour does this mean starting vol is 500hl and after one hour vol should be 475hl Wort volume = 500 hl = 50,000 L / hr 1 L = 10^-3 m^3 50,000 L = 50 m^3 /hr = 0.833 m^3 / min = 0.01388...

For a body at temperature T, the radiative energy per unit area E depends on 4th power of T. I can obtain expression for specific heat c by differentiating Stefan's law with respect to T. Would it be the correct way of approaching this problem? Or do I need to employ certain models from Solid...

Hello- In the attached screenshot from my textbook, I am trying to understand how they get from equation 6.5 to 6.5a. I have attached my attempt to solve it, but I am stuck evaluating the left side. I do not see how to get their result. Relevant information: k, T_w, T_inf, h and L are all...

The solution can be found at https://study.com/academy/answer/an-insulated-rigi... After using the two equations I can't see why (h2-h1)/(u2) should equal (T2)/(T1). Can someone explain why specific heat ratio is equal to temperature ratio?

I have supercharged my Toyota 4runner. The downside is the type of supercharger that I have bolted on (almost the only you can bolt on) replaces the intake plenum and has no way of cooling the air prior entering the combustion chamber. I read a little bit about how much heat is produced in the...

Just to clarify, I'm aware of the two equivalent expressions of the first law ##\Delta U = Q + W## and ##\Delta U = Q - W## when applied to a certain system, though my question is primarily about ##Q## - for which, as far as I am aware, the convention is almost universally that ##Q > 0## if heat...

I have one project in my mind bu tI have no eductaion in this topic. please help. question is: if there is container of water. and we have certain number of solar rays getting into this container how does process of water warm up look like comparing: 1. direct sun rays into water vs 2. on...

This is the question: You want to make an electric instantaneous water heater in which 5.0 liters of water flows past a resistance per minute and heats water from 10.0 ° C to 45.0 ° C. Calculate the magnitude of the resistance to use and the amperage. The flow-through is connected to 230V So...

For the heat engine: First I converted all the temperatures to Kelvin, ηmax=1-(333)/(1000)=0.667 ηclaim=(1*10^3)/(1.75*10^3)=0.5714 So the heat engine seems to be less efficient than a Carnot heat engine which means it can exist. For the refrigerator: COPmax=(253)/(363-253)=2.3...

Hi, So there is already a written solution which I have, but this is more a question about why we omit reflection that come back to the same mirror? Method: Let us consider one of the mirrors, we know it will emit a heat flux given by: q_{1} = \epsilon_{1} \sigma T_{1}^4 . Given that we are...

A Rankine Cycle heat engine uses ammonia as a working fluid, turbine entry temperature is 25 Bar at 60 degrees Celsius. The turbine outlet pressure is 4 Bar, the question is: what is the outlet temperature? and if the output power is 6 Gigawatt (6x10^9 watt) what would the mass flow rate of the...

Hello all! I have learned beta-keto acids are able to undergo carboxylation when subjected to heat. Do gamma-keto acids undergo decarboxylation when subjected to heat as well? If not, why? I identified C as a gamma-keto acid. Do you agree? Thank you for your help.

say I used a good insulator?

From what I understood from articles like this(https://scitechdaily.com/microbullets-demonstrate-graphenes-energy-absorbing-strength/) graphene is really good at distributing the energy from impacts over larger area and can even turn into diamond-hard material called diamene upon impact when...

Hello All, I wanted some insight on my answer to this problem. Lets say we have the reaction PCl3(g) + Cl2(g) ↔PCl5(g) ΔH0=-111KJ So for this reaction we know it is exothermic (because my textbook told me). But I want to make sure I understand why it is. If I were to look at this reaction and...

I tried to conserve the charge on the left plates of both the capacitors as intially the total charge on both is 48 and at t=t0 the total charge is 36(on c1) +4V(V is the potential across c2) so i got V=3 and then i conserved the energy Initial energy on both capacitor = final energy on both +...

Given this problem I have calculated the partition function as $$z=1+e^{-\beta E_1}$$ And calculated the average internal energy as $$<U>=\frac{E_1 e^{-\beta E_1}}{1+e^{-\beta E_1}}$$ And thereafter taking the partial derivative of <E> with respect to temp. T the specific heat obtained is...

In this case with a presence of the airgap, what should I do with the equation that is provided to be? Must the temperature gradient be caculated spearately (glass+air+glass) ? My tutor provided the hint that the heat flux should be constant for the windows, so in this case should I just omit...

I am seeing the heat conduction differential equation, and I was wondering about a boundary condition when the equation is of transient (unsteady) nature. When analyzing boundary conditions at the surface of say, a sphere, the temperature does not depend on time. For example, if you have...

Assume there is a boundary separates two medium with different heat conductivity [κ][/1] and [κ][/2]. In one medium, the temperature distribution is [T][/1](r,θ,φ) and on the other medium is [T][/2](r,θ,φ). What is the relationship between [T][/1] and [T][/2] ? Is it - [κ][/1]grad [T][/1]=-...

The expansion of space is about 68 km/s/Mpc, or 0.00002 km/s/light year. The radius of the sun is about 700000 km. Thus, initially ignoring additional forces, the change in radius of the sun due to the expansion of space is about 1.5*10^-9 m/sec, or 5 cm/year. I assume that this expansion is...

Hi, I posted a similar question recently and gained some insight on these types of problems. However, I am slightly stumped on how to approach this variation of the problem. So I know that: - there is no net change in enthalpy of the blocks and the engine as the processes are reversible -...

Hi All, In thermodynamics close system there are two const. processes in which we can calculate the heat: const. pressure const. volume I took 2 simple examples for these processes to test the results according the manufacturer data: For const. pressure I choose 1 liter 1.5 KW teapot For const...

Hi, I am quite confused about how to approach this problem. I have seen variations of this problem where there is a heat engine between two blocks, but in this case the surroundings are massless, so I don't believe that approach will work here. Method: I have first started with the case that...

Probably a silly question and a simple one for yourselves which I can't figure out myself. Hopefully I can explain it properly. Lets say I am standing on the equator and the sun is directly overhead. I am probably in the middle of a desert and it's around 50 degress centigrade. Assuming I could...

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...