Loss Definition and 793 Threads

Homework Statement I have a bloc sitting on a horizontal table, and we shoot a ball through it. The speed right before entering the block is v and the speed when it exits the block is v/2. I need to prove that the fraction of the initial energy that is lost due to heat is 3/4 - γ/4, where γ is...

Hello people of PhysicsForum Apologies in advance if my prefix selection is inaccurate and for my absolute physics noobness. I know no physics jargon so I'm sure my question will be phrased in the same way a 10 year old might. So here is my silly, trivial question: First of all, remove all...

[Moderator note: Thread moved from technical section hence no template. Question text from later in the thread added to this post to make things clear] "A power station generates electric power at 120kW. It sends this power to a town 10 km away through transmission lines that have a total...

Homework Statement A farmer installs a private hydroelectric generator to provide power for equipment rated at 120 kW 240 V AC. The generator is connected to the equipment by two conductors which have a total resistance of 0.20 Ω. The system is shown schematically in Fig. 1. (a) The...

Homework Statement Blobbing is one of the extreme attractions in aquaparks. A person is lying on a big raft positioned on the surface of water and filled with low-pressured air. Another person jumps down from a given height onto the opposite end of that raft, throwing the lying person in the...

Why is the probability of one-photon loss from a cavity in the time interval ##[t, t+\delta t]## is: ##\kappa \delta t\langle \psi(t)| \hat{a}^{\dagger}\hat{a} |\psi(t)\rangle## where ##\kappa## is the decay rate. It looks like the Fermi Golden rule but it's not exactly it.

Homework Statement Homework Equations power loss = I2R power loss = V2/R The Attempt at a Solution voltage across diode is 0.7V, current is 100A. resistance = 0.01 ohm. Power loss is I2R - 100 * 100 * 0.01 = 100 W Power loss across IGBT = V2/R. V across IGBT = V across Diode = 0.7. R for...

If an insurer were to offer a policy against data loss from a catastrophic event such as an electromagnetic pulse, the insurer would be in no position to pay when the contingency occurs, the reason being that all of his own bank account will have been wiped clean by the same EMP. Therefore I...

Homework Statement I would really appreciate it if you could give me a hand with this exercise, not sure on what I've done. Data: Moody: L=55*10-3m D=10-1m k=0.0002m Homework Equations ##Re=\frac{D*u*ρ} {μ}## ##Re=\frac{4*m} {pi*D*μ}## Relative roughness ##ξ=\frac k D## where k=rougness...

Homework Statement Calculate the energy loss loss ##\Delta T## for protons, deuterons and ##\alpha##-particles between ##10## to ##200##MeV when they're passing through a 2mm thick plastic scintillator. Suppose ##Z/A=0.56##, ##I=65eV## and ##\rho = 1.10##g/cm^3. Homework Equations Bethe...

Hello everyone, so I'm currently trying to find out how much power will be lost during reverse recovery of a MOSFET's diode. I'm using this paper for reference, https://www.fairchildsemi.com/application-notes/AN/AN-6005.pdf the equation they end up with is P= Qrr*Vin*Freq_sw the problem is...

Consider a spherical raindrop that falls at a constant velocity and whose radius ##r## is proportional to the distance ##h## fallen, i.e., ##r=kh##. Find the loss of gravitational potential energy (GPE) after it has fallen a distance ##h##. The given answer is ##mg\frac{h}{4}## but my answer is...

How Carbon-14 effectively gains a proton but no electrons when decaying to Nitrogen-14...?

I'm trying to determine the amount of load (power loss) a theoretical engine will suffer from an AC alternator, such as one you would find on an automobile engine, they produce something of 40 amps with 110 volts I believe? To be specific, I'm curious to know how much a theoretical engine would...

Hi there everyone, I'm doing some study on electronics and the section on the advantages of A/C over DC mentioned that AC has less copper loss (I^2 x R), But to me this seems contradictory to the skin effect. Could someone please tell me why AC has less copper loss.

I would like to ask you that why pressure drop is constant through pipe? How can we know that dP/dx=constant? Thank you.

Homework Statement Homework Equations Power = Work Done / Time Work Done = Force * Displacement PE = mass * gravity * height The Attempt at a Solution I got the first part (i) right, so the mass of the sea water is 1.32 x 10^12 kg. Part (ii) is the bit I am stuck on. My thoughts were that...

Homework Statement Homework Equations N/A The Attempt at a Solution Usually we are given a table, but how do we calculate the loss coefficient between 2 different pipes with different diameters? In this case, between the 5 and the 3 cm^2 pipes?

If we lost our hearing from a loud sound, does that just mess up the mechanics of the ear or does it affect the afferent nerves that would actually carry the signal if it could be detected? Thanks for any responses!

Hello everyone! I previously opened a thread asking about sound wave energy loss in aluminum discs based on thickness. I am looking to find out more about exactly how much using a disc that is twice the thickness of the other, (one is 1/8" and the other is 1/4") sound energy would be lost using...

Homework Statement why the author use major loss due to fluid friction is fL(Q^2) / 3(d^5) ? according to darcy weisbech , the major loss due to friction has the formula of fL(v^2) / 2gD why the author wrote it as fL(Q^2) / 3(d^5) ? I don't understand Homework EquationsThe Attempt at a...

Homework Statement the major loss in the fluid due to pipe friction is f(L)(v^2) / 2gD , (darcy weisbech equation) why the author use 4fL(V^2) / 2gD ? in the equation ? is it wrong ? Homework EquationsThe Attempt at a Solution

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...

Hello everyone! I am currently working on a project where I have a piezoelectric sound transducer connected to a glass tube via an aluminum disc. I got two aluminum discs with one twice the thickness as the other. I wanted to know which aluminum disc would work best, the thin one or the thick...

Homework Statement I was told that for loss of head at entrance , the degree of contaction depends on how thick the pipe walls is . i really don't know the meaning , can someone clarify ? the author also stated that the loss coefficients will vary , for very thin tubes , k is very high ? head...

Hi, I know this is simple but I'd like someone to clarify for me, because my lecturer wasn't clear: Obviously when the pipes are in parallel, the head losses across them are the same. But what about the total head loss for the parallel pipes as a whole? I have 3 ideas, but I'm not sure which...

Homework Statement Two identical balls A and B are dropped from rest into a tall column of viscous liquid. Ball A is dropped from the surface of the liquid while ball B is dropped from a small height ##h## above the liquid. Let ##E_A## and ##E_B## be the loss in mechanical energy of bal A and B...

Homework Statement we know that the formula of head loss is k(V^2) /2g , the k = 1 when the water is discharged from pipe to reservoir ...However , how if the water from pipe is released into atmosphere ? is it necessary to include the head loss due to exit ? if so , is the k still =1 ? in the...

Homework Statement from the previous thread , https://www.physicsforums.com/threads/minor-loss-in-pipe.869148/ , i know that formula of loss due to contraction can also be expressed as k[( mean velocity )^ 2 ] / 2g how about the formula of minor loss due to expansion , can we expressed as...

I take an interest in physics in my spare time (in IT during the day). I have a query regarding the 'problem' of information loss at a black hole, and would be grateful for some enlightenment. It seems generally regarded that any information going past the horizon of a black hole is...

1. The problem statement, all variables and given/known i am having problem of finding the major loss caused by pipe friction in this question. the formula of major loss is given by fL(V^2) / 2gD , how to get the total length of pipe so that i can gt the major head loss? . Relevant equationsThe...

Homework Statement which formula is correct ? the formula in the first ? or in the second ? one is using the mean velocity , while the another one is using velocity difference between vena contarcta and velocity at exit ... Homework EquationsThe Attempt at a Solution

Homework Statement what is the meaning of number of diameter N ? why the author make L = ND ? and then divide it by D ? Homework EquationsThe Attempt at a Solution

Homework Statement why the minor loss due to sudden expansion is given by formula of [( v_c - v_2) ^2 ]/ 2g ? Homework EquationsThe Attempt at a Solution can it be [( v_2 - v_1) ^2 ]/ 2g ?

Calculate the head loss per metre length of a capillary tube which has a bore radius of 0.45 mm when a fluid of density 850 kg/m3 and viscosity of 25 cP is flowing at a rate of 50 l/hr. State whether the flow is turbulent or laminar. I have attached my attempt at a solution using poiseuille's...

If there was a free-spinning effective weight of 20 lbs. at a 20" radius rotating at 180 rpm (15.7 fps?) and a force of 20 foot pounds was added, what would be the increase in velocity/speed? (Ignoring friction and wind losses).

Homework Statement See attached image: Homework Equations p/ρg + V^2/2g + z = constant head loss (major) = f * l/D * V^2/2gThe Attempt at a Solution To use the energy equation while incorporating head loss, I need to determine the velocity in each section of pipe. The problem is I don't know...

Homework Statement estimate the energy head lost along a short length of pipe suddenly enlarging a diameter of 350mm to 700mm which discharges 0.7(m^-3) of water per second . the solution given is Q1= Q2 = 0.7(m^3)/s 0.7 = pi ((350x10^-3)^2 ) V1 / 4 , V1= 7.28m/s 0.7 = pi ((700x10^-3)^2 ) V2 /...

Homework Statement A venturi meter is being calibrated horizontally and has a diameter of 75mm at the entrance and 50mm at the throat . The flow rate is obtained by measuring the time required to collect certain amount of water . The average number of measurement gives 0.614m^3 of water in...

I am designing 3ph distribution transformer. So for calculations regarding to design, I want specific iron loss. I know how to find out iron loss but that requires initially specific iron loss of material, which i don't know how to calculate. I also searched it on google and in some books but...

Homework Statement I'm trying to understand these two a bit better in terms of lasers. Fresnel Loss - The loss that occurs when there is a change in refractive index. Some light will be transmitted, while other light will be reflected back into the medium. This is bad for lasers because it...

Homework Statement , There is an Head Loss question, two pipes join and expanding parts 30 degrees from the horizantal. Homework Equations The Attempt at a Solution Before attemting a solution I try to understand what a1=a2=1.06 is? Would you like to give some information about it...

Homework Statement 1.) A 1200 kg car traveling at 20 m/s collides with a stationary 1400 kg car. The two cars lock together. Determine the speed of the vehicles immediately after the collision if 80% of the initial kinetic energy is converted to heat and sound during the collision 2.) Must all...

Homework Statement i was told that the friction loss is significant in short pipe , but not so significant in long pipe . However , the friction formula is given by formula f(L/D)(V^2)/2g , as L is big , friction loss is big . so the friction loss is big , right ? Homework EquationsThe...

Homework Statement in the notes , author said that the velocity within it is negligible? does the author mean the water velocity in the tank ? so the velocity (v^2)/2g in the 4.24 means the velocity in the pipe ? Homework EquationsThe Attempt at a Solution

Homework Statement My textbook says that high voltages are used for power transmission because according to the equation P=VI and P= I2R, power loss can be reduced. What confuses me is why the equation P=V2/R cannot used here? And if used, would be contradictory? I know that R is the...

Homework Statement A high-speed optical data communication system is composed of a transmitter, an unamplified transmission fiber link, and a receiver. The optical transmitter generates a 10-Gb/s non-return-to-zero (NRZ) signal using a 1550-nm laser diode (linewidth=2 MHz) followed by a...

Homework Statement why the formula of fricitional pipe loss due to contraction is given by formula : kc(V^2)/2g ? why the formula of fricitional pipe loss due to contraction can't be formula : (Va^2)-(Vb^2)/2g ? ,where Va= velocity at inlet , Vb = velocity at outlet ? Homework EquationsThe...

Hello, I was just wondering why is there an energy loss in helicoidal movement, specially in syncrotons. I know that there is energy loss because there is a production of X-rays, why this happens?

Hello everyone, Where can i get dielectric loss values of very thin SiO2 layers (nm) at high frequency range (GHz).? i.e SiO2 oxide layer dielectric loss of MOS (metal-oxide-semiconductor). I searched a lot on net but i didn't find any useful result, any reference is greatly appreciated.