Internal Definition and 993 Threads

Hello, Internal energy can be defined theoretically for one molecule (U = 1/2 Kb T) for example but entropy is defined for a system thus for many molecules. Then we define temperature equal to δU / δS but here U can be defined for one molecule, so S can also be defined for one molecule? How...

Homework Statement What is the internal energy of an electron moving at 0.750c0 in the Earth reference frame? Homework EquationsThe Attempt at a Solution E = mc^2 E = (9.11 * 10^-31)(.750)(3*10^8) However, this appears incorrect. What have I done wrong or what am i missing?

Homework Statement One litre cylinder contains 1 mole of the ideal gas molecules having the average kinetic energy of 0.1eV. What is the total energy of this gas? Homework Equations W = K + U The Attempt at a Solution I figured because the cylinder is closed, no stated temperature change, or...

An ideal gas is compressed from a volume of Vi = 4.50 L to a volume of Vf = 3.00 L while in thermal contact with a heat reservoir at T = 295 K as in the figure below. During the compression process, the piston moves down a distance of d = 0.120 m under the action of an average external force of...

Homework Statement Assuming water to be an ideal gas, enthalpy of vaporization is x joules per mole. I have to find change in internal energy an 100 degree Celsius for one mole of water. also find heat absorbed. Homework EquationsThe Attempt at a Solution I initially thought that during...

I've read back and forth in my chapter and tried consulting with my forumla sheet, but I cannot seem to find the correct formula. I bet I am looking at this question wrong, but I am fairly sure I need to use the -100 kJ for something to find the final volume and pressure , along with the given...

Hello everyone I got diesel engine, and there is a backpressure applied in the exhaust. I know that when the exhaust pressure reaches approximately 6 atm. the engine stalls. The question is, how I'm able to calculate this precisely, especially when the backpressure didn't reach it's maximum...

Homework Statement Hvap = 22.6E5 J/Kg. R=8.315E3 Jkmol^-1K^-1. 1kmol water = 18kg Keeping in mind that latent heats are enthalpies, what is the change in internal energy when 1kg water is converted to steam at pressure of 1atm and temperature of 100C. Homework Equations dU = dQ - PdV. The...

Homework Statement Show that the internal energy at constant entropy and volume decrease for a spontaneous process Homework Equations F = U-TS The Attempt at a Solution Use Clausius: dS-dQ/dT > 0 Assume constant volume: TdS > dU assume constant entropy this becomes 0>dU Since dU is...

Is there an easy explanation of total internal reflection of light using Quantum mechanics(or QED)?

Do black holes have an internal space? Consider the diagram. Inside the negative space, a "bubble" of sealed space, matter is free to move. https://dl.dropboxusercontent.com/u/109630018/temp/phys/blackholein.jpg

Why temparature is only dependent on internal energy of something, say an ideal gas.

I am currently studying a-levels in physics, maths and chemistry, after a below par performance in my AS levels I am working hard to try and boost up my grades, in lessons I am all okay but once i get to an exam i seem to lose all ability and end up losing lots of marks through silly errors or...

Thermodynamics question: Why does the internal energy have a lower bound? I tried to explain it using postulates, but cannot get the connection between the postulates. Please do explain it briefly. Thank you.

Hi, I am having a hard time answering this question. Any help will be appreciated. In 1938, the journal Nature published a paper by R. Emden titled “Why do we have winter heating?” (Nature Vol 141 pp. 908-9 – although you do not need to read it to answer the problem). This article asserts that...

Homework Statement Show that (∂(βA)/∂β)N,V = E, where A = E - TS is the Helmholtz Free Energy and E is the Internal Energy. Homework Equations A = E - TS dE = TdS - pdV + ΣUidni β = 1 / (kBT) The Attempt at a Solution (∂(βA)/∂β)N,V = (∂/∂β) * (βE - βTS) (∂(βA)/∂β)N,V = (∂/∂β) * (βE -...

Homework Statement [/B] Homework Equations Assumptions[/B]: Closed System and Quasi-static. p = 90 + 73,386*V -> V = (p-90)/(73,386) v = V/m Q - W = U2 - U1 mass balance: m = m1 = m2 The Attempt at a Solution At state 1: p1 = 110 kPa V1 = (110-90)/(73,386) = 2.725*10-4 m3 v1 = V1/m1...

The strong interaction keeps the quarks in very stable triplets or due to internal dynamics the quarks are re-arranged in nucleons from time to time?

Hello, We know that the electric field generated by a changing magnetic field is not conservative. But, for example let' say we have an EMF source that has an internal resistor, the voltage drop across the source is equal to EMF-rI where r is the internal resistance. My question is, inside the...

Homework Statement In a sample of wet steam at 11 bar, 75% of the total internal energy is contained in the vapour portion. Calculate the dryness fraction of the steam to 3 decimal places. Homework Equations u(kJ/kg) = (1-x)uf + x*ug x - dryness fraction f - saturated liquid state g -...

Homework Statement There is an optical fiber.A light ray enter it at i°.Total internal reflection occur at X. What are the necessary conditions for the light ray to travel along the core of the fiber? (I have canceled B and D already.) A.n1>n2 and angle i should be greater than a certain value...

Homework Statement A sample of an ideal gas goes through the process shown in Figure P20.32. From A to B, the process is adiabatic; from B to C, it is isobaric with 100 kJ of energy entering the system by heat. From C to D, the process is isothermal; from D to A, it is isobaric with 150 kJ of...

How is internal energy affected as cold water in a kettle transforms into hot water? [Mentor's note: edited to fix the formatting]

One of my hobbies is launching high altitude weather balloons carrying video cameras and scientific instruments to record various environmental parameters at high altitude — 90,000 to 100,000-feet. I'm planning another project and I was wondering how much pressure is being exerted inside my...

For a given closed system that does not experience phase transitions, does its internal energy depend only on its temperature?

Hello. I use a MC12079 as UHF divider by 256. Unfortunately this IC was oscillating at about 10 MHz. To correct this problem I insert a 47 k resistor between non inverting input and Gnd as Inverting input is used for signal to divide. It works, but I would like to know if this can have unwanted...

When a pressure vessel is subjected to internal pressure of 3 bar and external pressure of 4 bar..Is it right to say resultant pressure is 1 bar external? Does both cases (3 bar int& 4 bar ext,only 1 bar ext) produce the same result considering all other factors like thickness,material etc constant?

Homework Statement Hello, in the attached file shows a picture of the problem I need to resolve. The question asks to calculate the internal force in the member BC. There is a pin support located at joint A and D, which is not shown in my diagram, and it is also symmetrical, which makes things...

Homework Statement Hi there, I've been having problems with this kind of truss in the attached file. I'm used to resolving forces where the supports are located along the same x-axis, but this time I have the supports on the y-axis and a point load in the same direction. I haven't shown it...

ΔU=q-w and in a free expansion w=0 and Free expansion is an irreversible process in which a gas expands into an insulated evacuated chamber. Does this mean that free expansion is an isolated system? Meaning the walls of the container are adiabatic in which no heat can enter the system and so q=0...

I was reading about states of planetary ice in the following article. http://www.sciencedaily.com/releases/2015/06/150622182455.htm when it struck me that perhaps we should not assume that pressure increases as we descend into a large object. Like a cathedral ceiling a large cave does not exert...

If you have, say, two tubes of different internal pressures submerged to a given depth (for sake of the example, let's just say 1,000M underwater or 100 ATM), will the smaller internal air pressure tube experience a greater relative force from the water pressure? The water pressure on both tubes...

Homework Statement A car rubber has the volume 50 liters when it is bloated in a pressur 1.8 atm and in a temperature 293 K. After some hours of journey as an effect of friction the pressure will become 2atm. Find the change of internal energy of the air inside the rubber (U) Homework...

Homework Statement dX = U/V dV + U/p dp Write the differential of X in terms of the independent variables.Prove that this is an exact differential.Use the ideal gas equation of state to verify that X is actually the internal energy and that it satisfies the above equation. Would...

Homework Statement What is entropy of water at 5 Bar and an internal energy of 2724 kJkg-1? The Attempt at a Solution I have looked at the steam tables, i found where the pressure is 500kpa, then i do not know where to go from there. Thank You

Homework Statement A perfectly insulated and sealed spherical vessel contains an air-fuel mixture,somehow the mixture is made to burn causing a rise in temperature of the vessel and it's contents. Homework Equations Then which of the following is correct? A) Q=0 ,W=0...

Homework Statement Refer to the decay scheme of 137Cs What is the value of the internal‐conversion coefficient Homework Equations α = Ne/Nγ Ne=number of conversion electrons Nr=number of competing gamma photons for that transition The Attempt at a Solution α = Ne/Nγ =2/1 a=2 The correct...

1. One gram of water occupies a volume of 1 cm3 at atmospheric pressure. When this amount of water is boiled, it becomes 1671 cm3 of steam. Calculate the change in internal energy for this vaporization process. The heat of vaporization for water is 2.26 x 106 J/kg. 2. w = -PΔV, E = q + w...

Can external forces be considered as the forces acting from a distance and internal forces are the contact forces(except frictional forces)? since we know that according to Newton 3rd law every object making a force on a second object the second object will make the same force on the first...

When light encounters a boundary between a dense medium (glass) and a less dense one (air), it may undergo total internal reflection. But if there is another glass a short distance away, some light will jump the forbidden region by a tunneling process and enter the second glass medium. This jump...

Homework Statement When a nonideal battery is connected to a 3.0-Ω resistor in a circuit, the current in the circuit is 2.0A . When the same battery is connected to a 1.0-Ω resistor in a circuit, the current in the circuit is 3.0 A. What is the internal resistance of the battery? What is the...

If a beam of light undergoes total internal reflection, are there any equations to determine the angle of reflection based on the angle of incidence? Snell's Law: ## n_1sinA = n_2sinB ## is to my knowledge only valid under medium-to-medium transmission (for B: [0, pi/2]), correct? If total...

The terminal voltage and current are measured as the resistance is decresed through a cell with emf and internal resistance. Graph of V (y axis) I (x axis) shows straight line decreasing gradient. 1. Explain why terminal pd decreases as the current increases. is terminal pd the same as...

I'm working on a homework problem for Statics and I'm stuck. Could someone please help?Problem: Draw the internal force (N,V,M) diagrams and include all significant figures Here is all of my work: Resulting F from W1: W(x) = W1 ∴ F2=∫02b W1dx eq (1) ⇒ F2 = W1⋅2b x1 = (F1)-1 ∫02b W1dx =...

Homework Statement Hi, I am came across the following question and can't quite make complete sense of it: "Explain, in terms of internal energy, why a liquid cools when it evaporates". Homework EquationsThe Attempt at a Solution Could someone tell me whether this questions is implying random...

Hi, I'm new here so I'm not sure how things work but I'd like some help on a question. How do I go about finding an expression for both i_in(wt) and the average current? This is the inductive rectifier circuit I'm working with. http://i.imgur.com/HaWzFfQ.png http://i.imgur.com/kefMiOd.png...

Homework Statement Internal Energy Change Homework Equations N/A The Attempt at a Solution If internal energy change equals enthalpy change, then I am looking for the reaction which has the enthalpy change closest to zero. I know it cannot be A, as the formation of water is highly exothermic...

Question: is it possible to have any of the following - 1. Steam engine in a car 2. A steam internal combustion engine 3. A hydrogen internal combustion engine Background info Hi all, I am working on a fiction short story for fun. It is set in a parallel universe so history and a few...

Homework Statement Homework Equations Snell's Law n1sin(theta_1)=n2sin(theta_2) Total Internal Refraction: sin(theta_c)=(n_2/n_1) lambda_n=lambda_n The Attempt at a Solution So I drew the triangle and this is what I got, and well here is just a picture so far of what I have. [/B] I've...

Homework Statement Derive an expression for the change in internal energy of 1 mol of an ideal gas for expansion from volume V_i to V_f under constant pressure of 1atm where \gamma = \frac{C_p}{C_v}=\frac{5}{3} Homework Equations \Delta U=\frac{3}{2}nR\Delta T PV=nRT The Attempt at a...