Internal Definition and 957 Threads

I'm a bit confused about the following situation. In a irreversible thermodynamics process the molar heat of an ideal gas changes according to a function of the temperature, say ##c_v=f(T)## (which also leads to ##c_p=R+f(T)##) and I'm asked to determine the heat exchanged during that process...

How can you predict which product will be in excess if you have asymmetric hydroboration of internal alkynes and alkenes? For example, if I used 9-BBN or something sterically-hindered like R2BH...

Organic Chemistry question! Is 9-BBN too sterically hindered to even react with internal alkynes or alkenes? (to do hydroboration)

Homework Statement An ideal gass is at constant volume risen to a new pressure level of ##P_f##. Find te expression for the total heat brought to the system. Homework Equations 3. The Attempt at a Solution [/B] So ##PV=nRT## and ##E=Q## ##Q=C_v(T_f-T_i)## so i just have to find...

First, the electric/Coulomb force set up by a battery across its terminal is conservative, and its potential is given by the well-known V. I also understand the conventional usage of emf is as a voltage potential. However, a battery does more than just set up the electric field and its...

Homework Statement A battery with an emf of 60 V and an internal resistance (r) is connected to a 10 ohm external resistance. The power lost inside the battery is 50w. The same battery is then connected to a 4.0 ohm resistance. The power loss is 200w. What is the internal resistance of the...

I am trying to develop a basic model for calculating internal room pressure. I am using the vent opening equation. q = Cd A ((2 *delta P )/p)^0.5 If I have a set the vent 2500 mm2; A = 2.5e-3 m^2 Cd = 0.61 Internal pressure to be 102,135 and the external pressure to be 102,140; p = 1.21205...

So I just very recentlyearned about total internal reflection, which basically states that when the incident angle is large enough, the light will reflect back into the medium. I have a few questions: Say we have a set up with a tank of water and a laser pointer in it 1) does this mean that if...

A uranium-238 atom can break up into a thorium-234 atom and a particle called an alpha particle, α-4. The numbers indicate the inertias of the atoms and the alpha particle in atomic mass units (1 amu = 1.66 × 10−27 kg). When an uranium atom initially at rest breaks up, the thorium atom is...

Homework Statement 3. A fiber optic cable is essentially a thin fiber of plastic with n = 1.46, surrounded by a protective material with n = 1.32. The light can travel around a bend in the fiber if it can internally reflect inside the fiber. If the diameter of the fiber is d = 0.900 mm find the...

Hi all, I am reading some introducing materials on quantum information and quantum walk. In some materials, the author mentions to implement the related system with cold atoms and they mention the internal states. I learned the quantum mechanics some times ago but I didn't see any chapter in...

This is a servo horn. I'd like to make my own if possible, but I have a hard time figuring out how in the world they make the teeth inside these parts. I'm not really sure what to ask in google.

This is probably a very trivial question, but my brain isn't "playing ball" today so I'm hoping someone can help me with this. Suppose I have a system of ##N## mutually interacting particles, then the force on the ##i##-th particle due to the other ##N-1## particles is given by...

Homework Statement There is a pressure volume graph with the gas changes shown, forming a rectangle. The corners are labled A to D starting from the upper left corner heading on to the right until it returns to point A again. The question is at what point, or line is the internal energy of the...

I am wondering if equation $$C_v=(\frac{∂U}{∂V})_T$$ applies only to ideal gases or applies generally for any other system? The second question I have is can we use the following relation: $$dU=nC_vdT$$ in processes that are non isochoric (that is for processes where volume is not constant)? I...

Homework Statement Hello, long story short: I need to create a model of Li-Ion battery and I'm stuck on calculating the battery equivalent internal impedance. The thing is, I don't know the equation or even how to make one. However, I have a circuit drawing: Homework Equations Values in...

What is the difference between Q=m(u2-u1) + W & Q=m(h2-h1)? Basically I am trying to figure out 2 different sets of questions and apparently using these separate equations yield different answers, and I don't know which equation to use. From my understanding, both of them are used in...

I'm wondering how should I do analysis on those problems below: Figure 1: Figure 2: I mean, my professor, while doing an example very similar to Figure 2, he didn't do an imaginary cut in the region BD to find internal forces there, and the internal forces diagram that he drew only contained...

< Mentor Note -- Poster has been reminded to use the Homework Help Template and show their work on schoolwork problems >[/color] Hello everyone I have some questions on engine calculations that I need help in please. 1) A reciprocating internal combustion engine operates on a 4 stroke cycle...

Hi guys, firstly this is not a homework question despite looking like one. I'm curious about how one would go about estimating the internal pressure in a compliant balloon. I am assuming that I would need the following: 1. Stress-strain curve of the material 2. Diameter of the uninflated...

Internal engines got a flywheel connected to the crankshaft on one side, and on the other there is a wheel that drive all the engine accessories with a belt. If the main power output would be taken from the "belt" wheel and not the flywheel, would I receive the same power output? And if no, is...

Homework Statement A real battery can be modeled as an ideal voltage source in series with a resistor. A voltmeter with input resistance of ##1000\Omega## measures the voltage of a 1.5V worn out battery as 0.9V. What is the internal resistance of the battery. Homework Equations ##V=IR## The...

Homework Statement I can't understand the concept of internal path length. I can't understand what this value mean in the tree? For instance if a IPL of a tree is 30 then what does it mean for the tree. Tree does not have 30 nodes so what the path length means? Li is the number of nodes in...

How does the claddibg with lower refractive index reduce the light loss from the core? Thank you.

Homework Statement I didn't have enough space to make the topic any more precise. Here is the full question: Express the Internal Energy with Internal Pressure. Homework Equations [/B] This is what I know: the internal pressure is (dU/Dv)T the fundamental equation for internal energy is dU...

What is the difference? I read that thermal energy includes both kinetic and potential energy but isn't that what internal energy is? Cheers!

We know that internal energy of ideal gas depends only on temperature. Let's say we have 1 mole of ideal gas with pressure P1, volume V1 and temperature T. Let's call this the state 1. Equation of state for ideal gas applies: PV=RT. Now if we expand (or compress gas) isothermally, gas will then...

Homework Statement A question came to my miind: Wouldn't everything be conserved? I know that the law of momentum conservation only applies when the system doesn't have any external forces or the net of them is equal to 0. Lets just say that someone hits the ball with a bat, He applies a force...

Determine the resultant internal loadings acting on the cross section at C of the cantilevered beam http://imgur.com/Q4ZUTOq 1. Homework Statement F = 270 N/m Homework Equations ΣV = 0 ΣM = 0 ΣN = 0 The Attempt at a Solution section CB[/B] k/6 = 270/9 k = 180 N/m resultant force = area...

Homework Statement A gas bottle contains exactly 158 moles of carbon dioxide CO2. Find the change in the internal energy of this much CO2 when it is cooled from 36C down to exactly 25C at a constant pressure of 1 atm. The gas can be treated as an ideal gas with γ=1.289. The gas constant reads...

I'm struggling to understand a concept which I assume is basic, but I can't seem to fit the pieces together. When speaking about an ideal gas, I understand that ΔH = ΔU + Δ(PV) = ΔU + RΔT So far so good. I also understand the relationship: ΔU = Q + W... (W here is work being done on the...

Homework Statement Three resistors are connected in series to a battery. The resistances are R1 = 15 Ω ,R2 = 25 Ω , and R3 = 30 Ω and the current through the 15-Ω, resistor is 2.7 A . What is the potential difference across the battery terminals if the battery is ideal? What is the potential...

Homework Statement My textbook says that internal forces have no effect on an object's motion and that external forces are required to change the motion of an object. But, we looked at an expirement where a raw egg was spun and then stopped. After being stopped, it went back to spinning...

Homework Statement A pressure cooker is a nearly air tight sealed system. When seated on a stove burner and heated, water turns to steam and increases the pressure inside, resulting in higher temperatures so food cooks faster. Suppose 1/2 cup of water is inside the pressure cooker and it is on...

Hi, working on a project and I need some assistance due to my lack of education in mechanical engineering. With that said I will be as specific as possible. I need to figure out how much PSI is exerted on a piston during the power stroke in an external combustion emgine. I'm not sure how to...

Homework Statement A 1 m3 rigid tank has propane at 100 kPa and 300 K. The tank is connected to another 0.5 m3rigid tank which has propane at 250 kPa and 400 K by a ball valve. The valve is opened and both tanks come to a uniform state at 325 K. Calculate the change in internal energy and...

Hello If I take an extreme case, where a body has only an internal potential energy with zero internal kinetic energy, does this body have a temperature? Another question related to it: if two objects A and B having different temperature: A: having only internal potential energy and B having...

Homework Statement 10g of water at 0˚C added to 100g water at 50˚C Homework Equations Qhot+Qcold=0 Q=mcΔT Q=mL Σmc(Tf-Ti)=0 The Attempt at a Solution So I understand this problem, but I'm not sure when I am supposed to use Q=mL, L being the latency, I think. So with the problem mentioned you...

This is my first time here. Sorry if the formatting is a bit off. This is one of a few questions I am having difficulty with. I am not asking for any answers; and I have definitely done the work - multiple times - but have not been able to find the correct answer. Q) A uranium-238 atom can...

+ A man is holding a closed cage on the palm of his hand with a bird in it. When the bird flies with an upward acceleration inside the cage, it feels heavier. But the force due to the bird in the cage is actually an internal force on the cage, and internal forces don't cause acceleration of...

In my chemical thermodynamics class/notes (and other references I've used) it is stated throughout that internal energy U is a function of entropy and volume , i.e. it's "natural" variables are S and V: U = U(S,V) I suspect that I must take this "axiomatically" and move on. Since U is a state...

1. Homework Statement When volume changes from V to 2V at constant pressure then the change in internal enrgy will be? 2. Homework Equations ΔU= nCvΔT 3. The Attempt at a Solution I have used the equation ΔU= nCvΔT but the answer is PV/γ-1

Homework Statement A battery is connected with a resistor R1=4 om and then it is replaced with the resistance 9 om. In both cases the heat released in the same time is the same. Find the inner resistor of the battery. Homework Equations Q=UIt (U-tension; I-intensity, t-time) I=e.m.f/R+r The...

During Internal conversion, the nucleus transfer some energy to an electron in K-shell cause the electron eject out of the atom. After which there left a hole in K-shell then either by releases auger electron or characteristic X-ray the atom de-excited itself. During Electron capture, a proton...

Noticed that when u burn something its mass decreased like if u place a fuse on a scale and burn it, its mass decreases. But Antoine Lavoiser determined that if all the particles in the gas collected, like if you burn the fuse inside a closed bottle the mass stays the same...i don't understand...

Hello Physics Forums! I am currently writing a computer program that displays an enthalpy-pressure diagram for the refrigerant 134a. I am using the data and relation between specific volume, pressure and temperature found in http://eng.sut.ac.th/me/2014/document/LabMechanical1/HFC-134a_SI.pdf...

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...