Energy Definition and 999 Threads

Hi, I've a doubt about how to the energy is stored in a 'real' RLC parallel resonant network feeds from a sinusoidal source. Take a 'real' RLC parallel network having a resistor ##R_s## in series with the inductor ##L_s## (modeling its loss) with the capacitor C in parallel and consider it in...

How exactly would it then be calculated? Here's what I have tried: proton mass: 1.007276 amu Neutron mass: 1.008665 amu Sulphur-34 mass: 33.9678668 amu Calculation: 1.##(16\cdot1.007276)+(18\cdot1.008665)+(16 \cdot0.000549)=34.28117## 2.##34.28117-33.9678668=0.3133032## 3. 1 atomic mass...

I'm looking to find formulas to calculate the energy stored in a spring you would find in a clock. I have been having a hard time finding formulas that govern these types of springs. I have found formula in similar springs, such as the spiral-torsion spring found here but I believe this type...

The current density between the plates is J = 1 A/m2. So, I have to calculate first the magnetic energy in the whole space. Out of the sheets, there is no current, so the magnetic energy would be 0 in that places. Hence, U = J(1/2) \int_{inside the plates}A(r)dr, where A(r) is the vector...

The question is below. I tried reasoning that because x is constant, E is also constant however that gives me values in the range of 10^51. Then I tried to use numpy's ivp_solve function to solve the differential equation however I wasn't able to get that working either. Apparently I'm meant to...

Hello Gents, I am very confused about the working principle of gas turbines. I understand that air is first compressed in a compressor to obtain high pressure air at the inlet of turbine, but before air is introduced to the turbine, first it has to be heated to very high temperatures through...

Good day, If I consider my system to be an object and the earth, and the object is on the surface of the earth, then the system will have gravitational potential energy. Why couldn't I say that only the object (considering it as my system) has gravitational potential energy? Thanks

Guys, I have a problem that really needs you guys to help, I know it is a stupid question but please bear with me: Context: You have a block on a slope(has friction) you use a string to pull the block up with constant speed. Problem: So according to the network theorem, the work net is equal...

Hi all. I'm trying to prove energy conservation in a (maybe) uncommon way. I know there are different ways to do this, but it is asked me to prove it this way and I'm stucked at the end of the proof. I'm considering ##N## bodies moving in a gravitational potential, such that the energy is ##E =...

I am a student at high school who just finished a paper about nuclear energy and I really learned a lot from it. I found the topic interesting and really enjoyed learning about it. I now am searching out more people who know about it and as much information as I can fins while having good...

Inertia I = 2/5 mr² m=5.98* 10^24 kg. r=6.38* 10^6 kg. I= 9,736 * 10^37 kg. Earth rotation is V= (2 * pi* R)/T = (2*pi*6.38*10^6m)/(24*3600s)=463 m/s angular velocity w= V/r =463m/s/(6.38*10^6m)=7.27*10^-5 rad/s Enerrgy, E= 0.5* I*w²=2.57*10^29 j I get the...

In a globally hyperbolic spacetime you have a global time ##t: M \longrightarrow \mathbf{R}## which foliates it into Cauchy surfaces ##\Sigma_t## and the metric can be written ##\mathrm{d}s^2 = -N^2 \mathrm{d}t^2 + h_{ij}(\mathrm{d}x^i + N^i \mathrm{d}t)(\mathrm{d}x^j + N^j \mathrm{d}t)##. By...

Hi guys, a special relativity problem requested to choose the right graph representing relativistic momentum ##p## as a function of rel. kinetic energy ##K##, from these four: At first, I tried writing ##p## as a function of ##K##, in order to then analyze the function's graph and see if it...

Hello everyone, I am sorry if this question looks silly but my tutor has not replied yet and I need to work it out as soon as I can. Could someone tell me if they see any difference question 1 and question 2? Because I genuinely don't and it is driving me crazy. The assignment is about a coal...

As we know Energy is a scalar quantity. So when we add kinetic and potential energy to get Total energy. So addicting these two energy (kinetic and potential) comes under Scalar addition ? I just wanted to confirm it.

I have no idea how to do this. I've tried conservation of mechanical energy and it didn't work. Ek = Kinetic Energy R = horizontal range of the ball h = height from which the ball is released

So it seems the typical way to approach this problem is to consider the sphere when it has charge q and radius r. With uniform charge density ##\rho##, this becomes ##q = 4/3 \pi r^3 \rho## and so ##dq = 4 \pi r^2 dr \rho##. Using our expression for the potential outside of the sphere, we find...

We have a question about highly energized beta particles (6 to 22 MeV). Is it possible fore this radiation to affect the nucleus of an isotope and not just ionize it? In our case a copper-65 and copper- 63 isotope become their unstable neighbors Cu-64 and Cu-62 due to the high beta radiation...

VR = IR = 400 [ 29*10^-6 * 800 * 10^3 ] = 9280 P = IV = 400*9280 = 3.7 MW I was able to calculate the correct answer from the above, but why can't I use the equation P= V^2 / R?

In an article published in Scientific American, authors Adam Riess and Mario Livio wrote: Why negative pressure? I would think the pressure would be positive, thus making gravity repulsive.

I had found what U(x) was equal to already by plugging in the wave function and simplifying, which is (2h^2/mL^4)(x^2 - 3L^2/2) by the way. But the solution key that I have goes an extra step. After stating the equation of U(x) that I got, it says that: "U(x) is a parabola centred at x = 0 with...

D is correct, the reasoning is as follows: 1/2*(M1V1)^2 + 1/2*(M2V2)^2 = 1/2 * (M1 + M2) (Vcm)^2, since V1 =V2 =Vcm KE retained = KE final = 1/2 *M(Vcm)^2 Let me know if reasoning is okay? However, why A isn't correct?

I am trying to understand the scalar form of the Einstein field equations. I know that you can contract the stress-energy tensor using the metric. And for a perfect fluid model, this turns out to be the energy density summed with the pressure. This also gives the Ricci scalar. However, you can...

So always in my problems i had mass (M) but now i don't and it seems impossible to solve this problem if I don't have mass I think i am missing something. I was looking for similar problems in my book and internet and didn't find any.

Can energy be defined as an entity? The ability to do work is abstract, so is E=mc^2. It seems like energy is a catch-all phrase for something we can only describe in terms of other physical realities.

Energy is equal to Planck’s constant times the number of waves in 1 sec. The time scale for electronic excitation is far shorter then one second. So when we talk about the excitation of an electron from a lower level to a higher level occurring at a certain energy, are we talking about the...

Hello guys, I am designing a 1052 kwh solar farm with 2844 panels in Wales. These panels have to supply energy to a train station but I get minors coverage of the energy required if I do the following calculation which is based on the average sunshine of hours per month. What do you think about...

Hello everyone, I have found this on internet but I don't get the calculations. Can someone do the calculations and show me that the annual consumption is 600 kWh is you use a 200 Wh computer for 8 hours?: A complete desktop uses an average of 200 Watt hours (Wh). This is the sum of the average...

I understand the idea of a fictitious force. What I am confused about is the energy/potential associated with it. For example, if a cylinder of water is rotating, there apparently exists this centrifugal potential energy, which is obtained by integrating mrw^2 dr. Why is it that the...

I have some doubts with respect on how the functional derivative for the kinetic energy in density functional theory is obtained. I have been looking at this article in wikipedia: https://en.wikipedia.org/wiki/Functional_derivative In particular, I'm interested in how to get the...

I was thinking about the Gravity-B probe and the rotation of the satellite due to the Lense-Thirring effect. I was imagining that the satellite, once in orbit, was aligned to a distant star using retro rockets effectively rendering it non-rotating relative to that star. That being said, once...

I've been researching pem electrolyzers, but still don't understand how to mathematically express how platinum reduces the activation energy necessary to dissociate H2O. I've seen the Arrhenius equation solved before, but didn't understand how to get the values for it. Here are the operating...

Hi, I have to find the magnetic energy inside a coaxial cable of inner radius ##a## and outer radium ##b##, ##I = I## By using Ampere's law if ##r<a## ##B = \frac{\mu_0Ir}{2\pi a^2}## if ##a<r<b## ##B = \frac{\mu_0I}{2\pi r}## if ##r>b## ##B = 0## Then, the energy in a magnetic field ##E_b...

Of potential and kinetic energy in their various forms, in their own reference frames, which involve motion? Heat, light, nuclear, kinetic, etc., seem to involve motion. Does potential energy, in any way whatsoever, involve motion? Thermal does. Does nuclear energy involve motion? Seems to...

I have completed part a, from which I got the expression: Cv = 3KTn/(T_f) For part b, the first term is the electron contribution and the second term is the phonon contribution. I'm stuck on how to estimate the fermi energy for the potassium metal. I'm thinking I only need to consider the...

Hello! I've come across this forum looking for an answer to an odd question related to energy production. I have no intention of creating infinite energy so don't worry. Imagine a very strong balloon with a cord wrapped tightly around it. The balloon expands pulling the cord which spins a...

Textbooks always give an explanation for why electrons move between energy levels in atoms with an explanation something like this: 'An electron can jump to a higher energy level if it absorb's energy which exactly matches the difference between final and initial energy level'. My question...

Well, internal energy is the sum of the kinetic and potential energies of all the molecules within a given mass of a substance; this energy is associated with the random, disordered motion of the molecules. An example of internal energy is compressed gases; since gases occupy the total volume...

Yes, heat can flow into a body without increasing the mean kinetic energy of its molecules. Transferring heat energy to an object will raise its internal energy, this will not necessarily cause an increase in temperture. Specific latent heat is the energy required to change the state of one...

Is the purpose of the 0th, 1st & 2nd Laws of Thermodynamics simply to legitimate the thermodynamic properties of Temperature, Internal Energy & Entropy, respectively? It seems that all these laws really do is establish that these properties are valid thermodynamic state properties and the...

I was going to put this in the homework forums, but on second thoughts it's more conceptual so perhaps here is better. It's about problem 4, chapter 6 of Wald. Part (a) is fine, $$u^a \nabla_a u^b = \frac{\xi^a}{(-\xi^c \xi_c)^{1/2}} \left( \frac{\nabla_a \xi^b}{(-\xi^c \xi_c)^{1/2}} +...

Hello. Questions: Are antimatter, dark matter, negative mass confirmed that they exist and exhibit as phenomena? What about dark energy and negative energy? Do these types of matter behave as wave also? Do they exhibit such behaviour? About those types of energy i said, can they be transformed...

First, in section 20.4, after listing all the things gravitational potential energy does not do, they say the equivalence principle forbids it being localized. I thought I understood the equivalence principle, but maybe I don’t. Any comments explaining that would be appreciated. Second, they...

If a system is in an eigenstate of the hamiltonian operator, the state of the system varies with time only with a "j exp(w t)" phase factor. So, the system is in a "stationary state": no variation with time of observable properties. But the system could in theory (for what I understand) be...

We know that energy can be converted from one for to another , but how does it do that? How exactly does energy interacts with the quantum particles or with strings for that matter?

How much energy is required to double the radius of a uniformly dense stellar object? Express the answer in terms of mass and the radius of the object.