Heat Definition and 1000 Threads

So, I am casually sifting through a chapter in a thermodynamics textbook talking about the multiphase process that pure substances go through. I understand how the P-v and T-v diagram works and that out of the three properties (specific volume, temperature and pressure), two of them are...

Homework Statement I am having an issue trying to decipher this question, as I am not sure if it a lack of knowledge on my half or there is an assumption I have to make. Homework Equations ##\epsilon=\frac{W_{total}}{Q_{in}}## The Attempt at a Solution My issue is calculating the heat...

Does temperature increase when water is boiling at 100C in a closed system? I am picturing a scenario where I am boiling water in a pot to make pasta. However, I decide to close the pot as the water is still boiling. By doing this I am sealing away the system of study from the environment. Thus...

Homework Statement 1kmol of multatomy(I hope you understand - gas with many atoms) gas is heated for 100K (conditions of free expansion). I have to calculate the amount of heat supplied to gas. I have no idea how to do it. The right answer is 3320kJ Homework EquationsThe Attempt at a Solution

Homework Statement Homework EquationsThe Attempt at a Solution Since we want the fluid to be in liquid state before entering a boiler, and super-heated water can only reach 374°C before entering super-critical state, suppose after the expansion, the temperature at point 3 is still higher than...

I am currently trying to solve a problem for my dissertation. Help would be greatly appreciated. :) A silicon solar panel of area 1m^2 is being warmed by the sun. It achieves a constant temperature of 80 degrees celcius. I am trying to cool this panel which is constantly being provided solar...

I am trying to fill pipes with a volume of 556 cuft to 15,000 psi. I want to capture and re-use the heat generated from the compression process and re-use it. Is this amount of compression and heat exchanging possible with current technology

$$\frac{\partial T}{\partial t}=\alpha\frac{\partial^2 T}{\partial^2 t}$$ with an initial condition and boundary conditions $$T(x,0)=T_0$$ $$T(L,t)=T_0$$ $$-k\left.\frac{\partial T}{\partial x}\right|_{x=0}=2A\cos^2\left(\frac{\omega t}{2}\right)=A(\cos\omega t+1)$$ where $A=V_0^2/(8RhL)$...

I’ve attached an image of a solved problem related to the heat equation. Can somebody explain the -c + 3d = 0 comes from? I’m having trouble following the work shown.

Hi, I am a makeup formulator and need to make a lipstick that would be stable at 50ºC. The stability is tested in a chamber with an inner temperature of 50ºC. The lipstick is in a plastic packaging - a regular one that can be seen in any store. The question is: Will the temperature of the...

I'm doing a fun home project, and it involves water flowing through a metal pipe, where the surrounding is significantly lower temperature than the water in the pipe. The point of the exercise is to cool the water in the pipe as it flows through it. The question is, what influence does flow...

hello, I had made an DIY alpha type Stirling engine for my physics project and now I have to write an report about the relationship between the heat given to the engine and the motion of the wheel. I had searched a lot about Stirling engines and I learned about work, energy, efficiency...

Homework Statement 1.2.6. Supose that the specific heat is a function of position and temperature, c(x,u). (a)Show that the heat energy per unit mass necesary to raise the temperature of a thin slice of thickness deltax from 0°to u(x,t) is not c(x)u(x,t), but instead int((0->u)c(x,u’))du’...

Homework Statement Could someone look through my work? The parts where I wrote (??) are steps I am especially unsure about. Many thanks in advance. A large reservoir at temperature ##T_r## is placed in thermal contact with a small system at temperature ##T##. They end up at temperature...

Homework Statement When running, some (heat) energy is lost by the evaporation of sweat. If a runner loses 1.0 MJ( Mega Joules) of energy via sweating, calculate an approximate mass of sweat evaporated from the runner. Homework Equations Q = McΔT Q (Joules) = M (Mass) c (Maximum Heat...

I am not that smart when it comes to math. But I was wondering if there is a formula calculator or something online that would help me with the example of a problem. For instance if the attic is 130 degrees and I have a 14 inch round metal duct to my air conditioner in the Attic is there a way...

It is easy to understand heat conduction in a gas as the nucleus of atoms may collide with transfer of kinetic energy. But the space within a solid is vastly empty space and the nucleus of the atoms cannot collide. So if the surface of a solid is in contact with a hot gas, how is kinetic energy...

Hello everyone, For villages in Africa and Asia that still use wood, dung or other biomass in simple stoves which option do you think will be better? Concentrate solar energy into an insulated unit with a molten salt which can then be used at any time or build a simple biogas generator (large...

Homework Statement After a free expansion to quadruple its volume, a mole of ideal diatomic gas is compressed back to its original volume isobarically and then cooled down to its original temperature. What is the minimum heat removed from the gas in the final step to restoring its state...

Hello everyone, I'm aiming to produce a lightweight steam engine, which will essentially have a coil of copper tube inside the walls of a tube made of >your suggestions here<. this tube is the exhaust for a blowtorch. The principle is that this tube gets very hot, then transfers heat to the...

Hello: I have small question , as I read about the ATF research in the news ,a question present it self , why no one does any research on heat carrier in nuclear reactor that can absorb nuclear radiation and change it to infra red radiation ? Best H

I'm trying to get a better handle on the actual physical phenomena underlying viscosity (for Newtonian fluids). Something I could word in the format of "this happens (and this and this), and so the fluid resists flow." What I've found online is that when gasses are at higher temperatures, they...

Homework Statement For the reaction below, the constant pressure heat of reaction is qp = −3256 kJ mol−1 at 25 °C. What is the constant volume heat of reaction, qV , at 25 °C? 16 CO(g) + 33 H2(g) ⟶ C16H34(l) + 16 H2O(l) Enter your answer in kJ mol−1, rounded to the nearest kilojoule...

Hi there, I've got a Heat Transfer problem that I can't seem to get right. I will list all information in the problem without 'interpreting' it: Givens: 100 cm long cylinder filled with hot water, and constantly heated to maintain the water at 100°C. Heat is transferred via conduction from...

Homework Statement An insulated beaker with negligible mass contains a mass of 0.350 kg of water at a temperature of 76.5 °C. How many kilograms of ice at a temperature of − 23.9 ∘C must be dropped in the water to make the final temperature of the system 40.0 ∘C? Take the specific heat for...

hello my friends , i have two question about calorific value of coal why Lower heating value decrease with increase oxygen content but increase with increasing hydrogen , sulfur and carbon content ? Do this elements influence the higher heating value or not ?

Hello everyone, Homework Statement How many kilograms of lpg will you use if you heat 5 litres of water from 20C to 90C everyday for 30 days and how much will that cost if a 12.5kg cylinder is 1750 Rupees The attempt at a solution To heat 1 liter of water by 1C requires 4.18kJ so you then...

Hi all, I have encountered the idea of a heat bath but am slightly perplexed as to what it is. There was a textbook example that looked to find the number density expression for gas molecules as a function of position (image below). It then said that the probability ##P(z)## of finding the...

Hello all, I suffer from having a very cold house - as it is rented, we cannot put insulation in or change the windows (single glazed!), so I am looking for non-permanent options to maximise the warmth we can get from it. We have a log burner, and I have found that it is still kicking heat out...

Homework Statement A circular metal plate of diameter D needs Q Joule of heat to expand and the temperature changes from 40oC to 58oC. What is the thermal energy needed to expand identical metal plate having twice the diameter for same increase in temperature? Homework Equations Q = mcΔT The...

Can anyone point to a refereed paper exploring the heat absorbed by melting around 500 GT of ie per year (Antarctic - 127 GT pa; Greenland 286 GT pa; sea ice, glaciers estim. 100 GT pa)? As latent heat of fusion is 333.55 KJoules per Kg, I reckon the heat absorbed per year is around 1.67 X 1023...

Homework Statement An inventor claims to have developed a device with the following properties: net work output per cycle = 20,000 J heat output per cycle = 50,000 J high temperature = 450 C low temperature = 160 C Calculate the heat input per cycle. Homework Equations ΔETH = W + Q efficiency...

I have recently been curious about heat diffusion. If there is space in one dimension with any kind of temperature dispersed throughout, then the heat equation states that the derivative of the temperature with respect to time at any point equals some constant (k) multiplied by the second...

Hi all, the efficiency ##\eta## of a generic heat engine working between two temperatures is bound from above by the efficiency ##\eta_{\rm C}## of a Carnot machine working between the same temperatures. That is, if the temperatures are the same, a (ideal) Carnot machine is better than any...

1. In studies of the heat budget of the global free atmosphere, the concept of “latent heat” (now known as “enthalpy of condensation”) plays an important role[1]. 2. Both observation and experiment confirm that when humid air condenses the temperature of the remaining air increases[2]. 3. This...

I noticed that the outdoor fan on my residential, split-system heat pump stopped working in mid-October. I don't know for sure exactly when my outdoor fan on my heat pump stopped working. It might be that my outdoor fan did not work for months before I noticed that the outdoor fan did not work...

The outdoor fan on heat pumps always runs when the compressor is pumping refrigerant when the heat pump is in heating mode unless the heat pump has defect(s). I don't understand why the outdoor fan on a split system heat pump needs to run when the heat pump is in heating mode. When a split...

Hi! My question is: I understand that at noon-day it’s hotter because of the angle with which sun rays enter our atmosphere. But at the same time, I was wondering that the band of radiation responsible for heating things is infrared, and that at noon basically all bands of lower frequency than...

I read some Yogi can sleep naked at snow. Is there any scientific studies how they did it? Also what exactly regulate our body temperature? How much is the role of ATP in it?

1. Homework Statement The chemical reaction is given: 2C2H2 + 5O2 -> 4CO2 + 2 H2O. ΔrH* = -1299 kJ / mol. How much heat is released when 50 grams of C2H2 is burned? Homework EquationsThe Attempt at a Solution First, I convert mass into moles. M(C2H2) = 2*12+2 = 26 g/mol n(C2H2) = m/M = 50 g...

We all know how a thermostat works 2 different type of metal are attach together, when temperature changes 1 metal strap expands more than the other strap causing the straight metal strap to bend. 45 years ago when I was in college the professor brought a desk top heat engine to class. He...

Can liquid helium is superfluidity state conduct heat infinitely fast? I thought I have seen this is a paper somewhere a long time ago, but now I am not sure about that.

Homework Statement Keeping the cabaret door closed is important, so you install a sophisticated door control system that keeps the air exchange between inside and outside to a minimum. Why will such air exchanges always require the climate control system to work harder and consume extra...

Homework Statement Instead of pumping heat into the cabaret air from the outside air, you could simply put an electric space heater inside the cabaret. A space heater turns electrical energy directly into thermal energy. Why would operating a space heater consume more electric power than...

Homework Statement It is desired to heat 5130 kg/hr of cold benzene from 80 to 120℉ using hot toluene using double pipe heat exchanger. Toluene will be cooled from 160 to 100℉. The specific gravities at 68℉ are 0.88 and 0.87 respectively. A fouling factor of 0.001 should be provided for each...

Homework Statement Im confused about this and need help We did heat of nuetralization lab where we reacted 25mL of HCL and 25mL of NaOH using calorimeter. The temp difference was an increase of exactly 7degC One question asks me to show q_water (J) and to assume 50g water for the calculation...

Homework Statement Calculate the amount of heat emitted when 12.4 g of water freezes to solid air. Homework Equations heat of fusion = 6.02 KJ 1 mol H2O = 18.02 g H2O The Attempt at a Solution 12.4 g H2O x 1 mol H2O/ 18.02 g H2O x (-6.02 KJ) / 1 mol H2O = - 4.14 kJ I am unsure whether the...

Homework Statement I have delta H _solution, and also the mass of the solitd and q_water and q_reaction. Im using Dulong Petit to get MM but I need specific heat of the solid obviously. I don't have a final temp of the unknown solid, just the delta T for the water thanks for any help Homework...

My understanding of heat is the energy transferred as a result of temperature imbalance between systems. If two systems at different temperatures are in contact with each other, a temperature change for both systems and an energy transfer Q is occurring. It is known that Q=W for a closed...

The ans comes out (c) if I take specific heat at constt volume to be independent of temp. Whether the specific heat is always temp. independent for an ideal gas??