Thermo Definition and 267 Threads

Homework Statement Calculate the work done by an external agent in compressing 1.12 mole of oxygen from a volume of 22.4 litre and 1.32 atm pressure to 153 lit at same temperature. Homework Equations related to thermodynamics. The Attempt at a Solution

Homework Statement A certain metal whose thermal expansion coefficient \beta is 5,0 × 10^-5 °C^-1 and whose isothermal compressibility \kappa_T is 1,2 × 10^-6 atm^-1 is at an initial pressure of 1 atm and an initial temperature of 20°C. A thick layer of Invar is thermally insulating the...

I've been trying to solve this for a long time now, I even posted it on this forum a long time ago but no one replied, not even a single response :frown:, I'm not sure if the folks thought I was just trying to make them solve the problem for me or if they actually did not understand it, either...

Hi everybody, i am new to Physics Forums and I have a problem that is confusing me. Any help would be much appreciated. Problem: A perfectly insulated box has vacuum inside of it (it is evacuated entirely) and is sitting with standard atmospheric surroundings (1 bar, 298K). It is then...

you want to boil a pot of water at 110 C diameter of pot = 15cm atmospheric pressure 101 kPa what weight lid should you use? i looked up the steam tables and water boils at 110 C at 143.27 kPa so do i use that pressure or 143.27-101? (gauge pressure) i used gauge and got something...

Homework Statement First law can be written dU = TdS - PdV where the internal energy U may be written in terms of any two of T,P,V,S. I have to show that (DT/DV)s = -(DP/DS)v where D is partial d, and the subscripts s and v mean hold those constant.. Homework Equations The...

Homework Statement derivation of compressibility factor vs. reduced pressure I am supposed to derive the graph by solving equations Homework Equations Van der Waals equation of state compressibility factor, Z = (Pv)/(RT) reduced pressure = P/critical pressure Z = f(Tr, Pr) The...

So I wrote my Thermodynamics final today and one of the questions were as follows: A reversible heat engine supplies a reversible heat pump. Both draw off of a temperature reservoir T (can't remember the exact value, but there was one). The heat engine discharges heat into TL, and the heat...

If you were to combine a diesel cycle and a steam cycle (crower cycle) in 1 p-v diagram, what would it look like?

Hello, I am a Security Engineer and deal with system security. I have an interest in Physics and wondered if the second law of thermodynamics applied to system security. My thought is... if you secure a [computer] system as much as possible (this can never be 100%) and leave it. Over time...

ive got this q in my homework calculate the pressure at the centroid and hence the force acting plate. the surface is free liquid is water. ive using a formula l x e = y l being length or depth in this case e being value of water which i found to be 1 x 10 to power of 3 kg/m3 y being the...

Homework Statement An insulated beaker with negligible mass contains liquid water with a mass of 0.325 \rm{kg} and a temperature of 69.9 C. How much ice at a temperature of -15.0 C must be dropped into the water so that the final temperature of the system will be 39.0 C? Take the specific heat...

Homework Statement A person of mass 70.0 kg is sitting in the bathtub. The bathtub is 190.0 cm by 80.0 cm before the person got in, the water was 10.0 cm deep. The water is at a temperature of 37.0 C. Suppose that the water were to cool down spontaneously to form ice at 0.0 C, and that all the...

How do you use the C_ij matrix to find the harmonic frequency (or frequencies) of a diatomic molecule, the OH (hydroxyl) radical? (I have no idea how to set it up for this.) This is from Feynmann's book on Statistical Mechanics...

Homework Statement Air is heated from 300 to 350K at constant volume, Find 1Q2. Homework Equations 1Q2 = m(u2-u1)+1W2 u2-u1 = cv(t2-t1) The Attempt at a Solution The PV diagram of the process is straight up, so the area under the curve is 0, so the work done is zero. Cv is .717...

I need to make thermal analysis for new gear box design to get the answer: do I need additional heat exchanger for that gearbox? I would like to get a help as a source for engineering calculations. Of course, I have already calculated power losses in bearings with TIMKEN software. I don’t have...

Hi this is my first post here. I am attempting to calculate how long it takes for a soda can(355ml) to change from Current room temperature(75F), to say 38F, however the refrigerator or ambient temperature in this case is 35F. I was given a corollary from a friend, but the values I get in...

A piston / cylinder arrangement with an initial volume of 1 ft^3 contains water at P = 20 psia, T = 320 F. The piston expands against a linear spring until the final temperature and pressure are P = 10 psia, T = 400 F. D)calculate the work and heat transfer in the process, and report in BTU...

Homework Statement If 0.8kg of water at 100 celsius is mixed with 0.8kg of water at 0 celsius, is this process reversible? Homework Equations Entropy: S = mcln(T_2/T_1) The Attempt at a Solution I've already calculated the entropy of the process, which is 81.1 J/K. But how do I...

What is the difference between \DeltaH and \DeltaE in a constant volume process ?

Howdy, Just studying for a test, need to clear something up and I can't find it in any of my books. My question is in regards to N, which to me seems like it is the same as <N> also known as the thermal average occupancy. This quantity represents the thermal average number of the orbitals in...

Homework Statement This is for Statics and mechanics of materials 1... In this project, we were tasked with the re-design of a cheap thermal switch that is to be a component of a low cost product. The switch consists of three metal strips that are bounded on the top and bottom by a rigid...

Homework Statement I have a mixture of saturared water liquid vapor mixture at 200 c, volume = .03 m^3 at 15.54 Bars... the mixture undergoes an isothermal expansion and the volume doubles, what is the new pressure? mtotal = .301 kg Homework Equations this is my prob not sure which...

This is just a conceptual think I have been thinking about. Hopefully I am not just missing something obvious. Imagine we have a large vertically oriented cylinder filled completely with a saturated liquid and the surface contacting the liquid is providing a constant heat flux to the fluid...

this problem is quite long, all I am asking is some for some help by clarifying and hints so i can try to solve this question. Thanks in advance! Consider the combustion of liquid ethanol, C2H5OH(l), to form CO2(g) and H2O(g). Suppose we have 1 mole of ethanol in the presence of 4 moles of O2...

Homework Statement We have a tank of air at 7 atm, 30 L, and 293 Kelvin(20 Celsius), and a flat tire with 1atm, 10 L (Constant), also at 293 K (20 C). The valve is opened quickly and closed quickly when the pressure in the tank reaches 6 atm. Using the Ideal gas assumption and taking the...

Homework Statement I have a system u =Av-2exp(s/R) N moles of this substance initially at T0 and P0 are expanded isentropically until the pressure is halved. What is the final temperature? Homework Equations du = \partialu\partials ds + \partialu\partialv dv du = Tds - Pdv...

Hello... first post here so take it easy on me. From the Book: "Aquatic Systems Engineering: Devices and How They Function, Selection Installation Operation" by P.R. Escobal In the section about heat loss (section 12.9) the author gives the basic conductivity equation in the form: Q =...

Homework Statement (This isn't for class, but still worthy of discussion!) If you heat a room with say a fireplace, why does the total energy not increase? Homework Equations PV=NkT The Attempt at a Solution This is a qualitative answer (mostly). The total energy of the...

Thermodynamics makes good predictions for macroscopic experiments, but the actual physics is going on in the microscopic particular level. The second law of thermo is often thrown around, usually by people who couldn't explain F=ma back to you. My question is the way the second law...

The value of H° for the reaction below is -1107 kJ: 2Ba(s) + O2(g) --> 2BaO(s) How many kJ of heat are released when 5.75 g of Ba(s) reacts completely with oxygen fo form BaO(s)? i worked out the moles of Ba which was 0.0412 then times by -1107 whcih is 46.4 however the answer is...

Thermo Help! Compressbility Homework Statement Ethane in a rigid vessel is to be heated from 50 psia and 100 F until its temperature is 600 F. What is the final pressure of the ethane as predicted by the compressibility chart? Homework Equations Pr=P/Pcr Tr=T/Tcr Pv=zRT The...

Homework Statement How do I write equations on a computer? I need some help with some Physics equations. I am about to take a course. I have very poor math skills, so I am hoping to improve my confidence, while learning some interesting equations. I have included Boyles Law as it is...

Homework Statement A nitrogen gas-liquid mixture is in a 20 cubic foot tank at a condition of 161 R with an initial quality of 0.1. Heating occurs at a rate of 10,000 Btu/h until the pressure reaches 100 psia. At this condition the BHE safety valve opens and maintains a constant pressure as...

Hi everyone, I was wondering if it might be possible to drive the spit on my barbeque using a thermo cyphon in a closed water system... The idea being to have a standard 22mm domestic copper pipe running through the bbq fire. Both ends of the pipe would be connected to a small water tank...

what is Vr... I know how to get Vr from my text but not sure what it is and what its used for...Im trying to find values for internal energy for an otto cycle question...im working on EES but only know how to get the values for Vr from the text

Homework Statement Classical Ideal Gas in 3 Dimensions In a classical ideal gas, we treat molecules as non-interacting point particles moving in the x,y, and z directions. These particles' velocities (in each respective direction) are statistically independent...

Hi...I would very much appreciate thermo help. I am using software that requires enthalpy data to be in units of J/m^3 (i.e., enthalpy per unit volume). The software also requires that enthalpy always increases with increasing temperature. My problem is that my enthalpy data in J/m3 do not...

Homework Statement The problem asks to find the energy conversion efficiency of a blower-nozzle combination that produces a velocity of 30m/s for air with a density of 1.1kg/mcubed. The nozzle has a diameter of .15m input power is 1 hp Homework Equations given the flow rate =...

Hello, I am trying to derive a formula for entropy. I have: dS= Cv/T dT + R/(V-b) dV and want to get: S= Cv*ln(T) + R*ln(V-b) + constant. Math rules seem to say i can't just integrate this up even though it looks obvious since i have two different d's on the right hand side. Maybe...

I have a test coming up tomorrow, looking for all the equations, I am in AP Physics course. TY

A partition separates the two compartments of a vessel. The vessel is submerged in a constant temperature bath at 200C. Compartment A contains 2.00 kg of water at 200C, 50.00 bar and compartment B contains 0.983 kg of water at 200C, 1.00 bar. The partition is removed and the water in both...

Homework Statement The light energy that falls on a square meter of ground over the course of a typical sunny day is about 20 MJ The average rate of electric energy consumption in one house is 1.0 kW one of the questions was: On average, how much energy does one house use during each 24...

Homework Statement A hypothetical substance has an isothermal compressibility k = a/v and an expansivity B = 2bT/v where a and b are constants and v is the molar volume. Show that the equation of state is v-bT2+aP = g where g is a constant. Homework Equations k= -v(dP/dv)T B =...

im given the equation: k d^{2}T/dx^{2} = 0 over 0 < x < L = 0.4 with T(0)=T and -k dT(L)/dx = h(T(L)-Tinf) i tried to solve it and i got T(x) = (-h(T(L)-Tinf)x)*(1/k) the book gives T(x) = ( (k+h(L-x))T+h*x*Tinf)*(1/ (k+h*L) ) i don't understand what went wrong... help!

Suppose the following system for a capacitor. Given: dE = TdS +\phi dq Where: \phi is the potential and = \frac{q}{C(T)} Find the heat absorbed in increasing charge from 0 to q. (Capacitance is a function of temp). So, I get dF = \phi dq and then F = \frac{q^2}{2C} Next, I tried...

I need some clarification! Thermo Cycle Homework Statement One kg of Refrigerant 22, initially at p1=.9MPa, u1=232.92 kJ/kG, is contained within a rigid closed tank. The tank is fitted with a paddle wheel that transfers energy to the refrigerant at a constant rate 0.1kW. Heat transfer from...

A 0.2-m-thick plane wall is constructed of concrete. At steady state the energy transfer rate by conduction through a 1-m^2 area of the wall is 0.15 kW. If the temperature distibution is linear through the wall, what is the temperature difference across the wall, in K? i don't even know where...

I'm planning on taking a statistical thermodynamics grad course this Fall. Being an ME I am very familiar with classical thermo but what other topics should I be keen on? Any specific field of mathematics like abstract alg(only math I have not taken) I should be worried about? Also, I am...

Homework Statement A classical system of N distinguishable, non-interacting particles of mass m is placed in a 3D harmonic potential, U(r) = c \frac{x^2 + y^2 + z^2}{2 V^{2/3}} where V is a volume and c is a constant with units of energy. (a) Find the partition function and the...