I hope every student and professional will benefit from this thread.

I'll start in the next post.]]>

Does QFT have problems]]>

Read: https://www.physicsforums.com/insights/little-excuse-ask-question-cold/]]>

I have a dream and planning to invent new digital device like smarthphone,...

Where to start learning electronics engineering on my own?]]>

https://www.wired.com/2014/06/the-new-quantum-reality/]]>

So--why are these...

Reference Probes in pH and other electrochemical measurements]]>

Neutron stars and black holes]]>

The length of a simple pendulum is about 100 cm known to have an accuracy of 1 mm. Its period of oscillation is 2 s determined by measuring the time for 100 oscillations using the a clock of 0.1 s resolution. What is the...

How do I use the number of oscillations given?]]>

My wife just drew this

View attachment 93241]]>

What are your plans for turning 25?]]>

A 410kg bluefin tuna rests motionless at a depth of 15m below the ocean's surface. The absolute pressure at this depth is 251,700 Pa. What is the volume of the fish?

absolute P=gauge...

Absolute Pressure]]>

FIGURE 4(a) represents a system to measure acceleration (i.e. an accelerometer). It shows a piezoelectric crystal that is connected to an amplifier and display via a length of coaxial cable2.

A piezoelectric current is...

Laplace transform for a piezoelectric acceletometer]]>

I'm fine with the first part. Part b) is causing me trouble

http://imgur.com/xA9CG5G

integral form of Particular solution question]]>

- basic guidelines on how to create an outdoor antenna (you can send links
- the most suitable type of antenna that can receive 70 MHz tv station frequency. The antenna will be mounted less that 3 m from the ground.
- computations that i need to know (you...

Outdoor antenna design]]>

But all throws dreams were killed off by physics as I got...

TV show, movies, and book, that are ruined by physics]]>

Higher order terms in perturbation theory (QFT)]]>

My question is if an associate's degree in...

Should I finish my engineering associates degree?]]>

An Fe nucleus (A=57) decays from an excited stated to the ground state by emitting a gamma ray. The energy of the photon is 14.4 KeV when the nucleus is held fixed. If the nucleus is free to recoil then the energy of the photon...

Energy of the photon emitted in a gamma ray decay]]>

Given:

An object at rest with respect to an inertial reference frame S.

2 other inertial reference frames S' and S''.

S' has velocity (vx, vy) = (-.6c, 0) with respect to S.

S'' has velocity (vx, vy) = (-.6c, +.6c) with...

Trouble with 2 step velocity transformation in SR]]>

Software - Suspension Analyzer by Performance Trends

In order to understand the complexity of a Formula Cars suspension, a basic knowledge of the stock car suspension should first be mastered. When...

Race car suspension Class]]>

A couple of questions about this:

1) how do we know these are photons and not some other force carrier if we cannot detect them directly?

2) can...

Why can't we detect virtual photons ?]]>

A free neutron is unstable and decays into proton electron and an anti neutrino. The rest masses of these particles are ##m_n = 939.6 MeV, m_p = 938.3 MeV m_e = 0.51 MeV ##and ##m_{\nu} = 0 ## so that the change in the total...

Calculating the energy of anti neutrino]]>

Renting out a house in a university area?]]>

Two solid spheres one of mass 'm' and other of mass '2m' are comin towards each other(translationally) with a velocity v1 and v2.After collision the sphere of mass 2m comes to rest and the sphere of mass m does oblique...

momentum -- pure rolling and trajectory physics problem]]>

For all natural numbers n, prove whether the following is true or false:

n

From SQA Advanced Higher Mathematics 2006 Exam Paper

I can choose from the...

Prove True/False that n^3-n is Always Divisible By 6]]>

1020 x...

A spherical buoy of diameter 0.5 m and mass 35 kg is attache]]>

let's use this symbol to denote the unit impulse function δ

When integrating the unit impulse function (from negative infinity to infinity) ∫δ(t) dt I know that this results in a value of 1 and is only nonzero at the point t =...

Integral of unit impulse function?]]>

Assumption of local thermodynamic equilibrium in a fluid]]>

As my first post here I would like to open with a situation I have been struggling with

I have attached a simple diagram of my problem

I have 2 cylindrial N52 neodymium magnets axially aligned with each other with opposite poles facing each other....

Neodymium magnet partial shielding]]>

Technicality with Noether's theorem]]>

Double slit experiment wave interference?]]>

I am interested in rotating convection. Anyone know of any open questions, or where to find research topics in this area?

Cheers.]]>

Advances in Machine Intelligence question]]>

View attachment 197487

$$1^2+2^2+3^2+...+n^2=\frac{n(n+1)(2n+1)}{6}$$

$$S_n=2\{[f_1(x_1)-f_2(x_1)]\Delta x+[f_1(x_2)-f_2(x_2)]\Delta...

Area between two graphs as a sum]]>

Rovelli on the notion of "now"]]>

Solution Credit: @SSequence for 2a, 2B

1) In order for a solution to count, a full derivation or proof must be given. Answers with no proof will be ignored.

2) It is fine to use nontrivial results without...

Math Challenge by Erland #2]]>

Bring Me A Flower

Flowers have been a very popular contest theme. We have had many glorious photos over...

PF Photo Contest - Bring Me A Flower (4/22-5/5)]]>

I've used z* to mean z conjugate.

Given the equation z + 2iz* = 8 + 7i, express z in the form a + ib.

From SQA Advanced Higher Mathematics 2005 Exam Paper

n/a

I...

Express z in the form a+ib]]>

Distrubution of cosmic rays]]>

The solution merely states that the operator is not Hermitian because

< Af | g > = -< f | g > - < f | Ag > ≠ < f | Ag > using integration by...

showing an operator is Hermitian using integration by parts]]>

When a photon hits an electron, is that an event? Does that "event" have a beginning and an end?

Could the big bang be considered the only event?

Can there be any...

Do events exist in reality?]]>

The decomposition of phosphine 4PH3(g) + P4(g) + 6H2(g) is first-order with respect to phosphine with a rate constant k = 0.0155 s-l at 953 K. If the decomposition occurs in a constant-volume batch reactor at 953 K, calculate,...

Chemical Reaction Engineering homework]]>

The CC and cosmological event horizon radiation]]>

below is my question :

View attachment 197517

all of the equatios used to solve this problems are equations for free source RLC circuit.

so far i have...

Question about free source RLC circuit]]>

https://www.theguardian.com/tv-and-...esses-as-an-unexpectedly-racy-albert-einstein

I've yet to see it but would...

Einstein Biography on National Geographic Channel]]>

where ##R(t)## is the proper radius of some spherical volume with us at its center.

Let us assume that there is a mass ##M## inside this spherical volume of radius ##R##. The...

Argument that a maximum density Universe expands linearly]]>

thanks,]]>

An 7.80-cm-diameter, 400 g solid sphere is released from rest at the top of a 1.70-m-long, 20.0 degree incline. It rolls, without slipping, to the bottom

I=2/5 Mr^2

K = 1/2 m*v^2

K

Calculate angular velocity of a ball rolling down incline?]]>

Actually, my major is tribology and I have no experience in designing control system.

So it is really big problem for me.

Anyway, this is my simple model of tribometer which applies normal load on the surface....

I need help with matlab]]>

if I need higher current for 1 second, I can do it?

The heat is the problem here?]]>

Bull charging and you charge the bull]]>

isothermal process]]>

Transition between Quantum Mechanics and QFT]]>

Some Questions About Gold Nanoparticles]]>

Can anyone explain why the pore pressure at C is given by( H1 + z + (h/ H2)(z) ) (y_w) ?

Shouldnt it be ( H1 + z + ) (y_w) only ?

Its meme status and guys use it to gain superiority.....in their own minds.

Looking for cool graphics so I can provide a counter T shirt with a DYEP bro, as per title.

This is...

Do You Even Physics bro.]]>

-Mathematics of Classical and Quantum Physics...

What are the best $20 mathematics of physics books?]]>

What other chemistry courses use the periodic table?]]>

2

Let f_n: [0,1]-->R be a uniformly convergent sequence of continuous functions. Let f: [0,1]-->R be the uniform limit of {f_n}. Let c be an element of R. Suppose that for all n there is some x_n in [0,1] such that f_n(x_n)=c....

Analysis Question]]>

Its a classic problem about a puck that is rotating on a frictionless tabble with a velocity v1 and radius r1. It is is connected to a string which runs through a hole a the centre of the table. The string is pulled from below...

Pulling a puck through the hole]]>

An ac series circuit consists of a voltage source of frequency f = 60 Hz and voltage amplitude V, a resistor of resistance R = 163 ohms and a capacitor of capacitance C = 6.2x10^-6 F. What must the source voltage amplitude V be...

Source voltage amplitude]]>

Consider the free real scalar field [itex]\phi(x)[/itex] satisfying the Klein-Gordon equation, write the Hamiltonian in terms of the creation/annihilation operators.

Possibly the definition of the...

Hamiltonian in terms of creation/annihilation operators]]>

Charge on a conducting shell]]>

That condition seems...

Ignoring boundary term in the action]]>

Have CFM at one point, need to find it at another point]]>

Basic question - balance of forces...?]]>

The same horizontal force is applied separately to two objects initially at rest on a horizontal, frictionless surface. Object A has less mass than object B. In each case the force is applied for the same length of time. Which...

Conservation of Momentum Problem]]>

I am trying to understand how vector images are formed and manage to be scaled up or down without distortion. Bitmap images are easy: they are a grid of pixels and each pixel has a certain color. Scaling a bitmap image of 10x10 pixels implies adding new extra pixels and using...

Vector images vs Bitmap images]]>

I seem to be able to find a unique solution given the initial condition of the form y(c) = 0, but the theorem says I won't be able to do so, so I am kind of confused.

I just want some clarifications. Does the uniqueness and existence theorem say anything about the...

Uniqueness and Existence Theorm]]>

Magnitude-5.3 earthquake hits Japan's Fukushima

http://www.usatoday.com/story/news/world/2013/09/19/japan-fukushima-nuclear-plant/2835493/

1. Does a magnetic field in a current-free region of a curved spacetime still satisfy Laplace's equation? Or is...

How do magnetic fields curve spacetime?]]>

"Space and Stuff"]]>

Please start off with "Today I learned". Keep commentary to a minimum and just LIKE posts. I'll start!

Today I learned that you clean...

Today I learned]]>

rotation and balance]]>

5.5 MeV alphas hit Be-9 and produce carbon with a gamma. the Q value is 10.65

I have to find the kinetic energy of the carbon nucleus and the gamma and im to ignore the gamma ray momentum.

T = p^2 /...

Find product kinetic energies in (α,γ) reaction]]>

The book says the friction force (F) per unit volume = $$\frac{dF}{dy}=\mu\frac{d^2U}{dy^2}$$

They say $$\frac{dU}{dy}=\frac{U_\infty}{\delta}$$

This makes sense to me, delta is the thickness in the y direction,...

second derivative of friction force question]]>

Object load distribution]]>

A beam of $$^{39}K$$ atoms is slowed with a Zeeman slower with laser light tuned to the $$4s^2S_{1/2} --4p^2P_{3/2}$$ transition with $$F=2, m_F=2 -> F'=3,m_{F'}=3 (\lambda =767nm)$$ Nuclear spin $$I=3/2$$. The most probably...

Shortest possible damping time in Optical Molasses]]>

The scientific paper: Nature and...

Super-Earth Found in Habitable Zone of Nearby Red Dwarf]]>

Here (sigma)i is Pauli matrix.

Next one is, what will we get from simplifying

<Alpha|vect{S}|Alpha> where vect{S} is spin vector & |Apha>is equal to " exp[{i×(vect{S} dot...

Proof of some identities regarding spin angular momentum.]]>

View attachment 197508

2. Relevant equations

No equations needed

I know that capacitors are used to store charge but what exactly is the 40 micro-farad capacitor doing? No emf/voltage...

Capacitor circuit]]>

If it...

Planck Scale]]>

Hello there,

I am stuck at a problem, and I need some hits/solution strategy to get going. Suppose we consider linearized gravity, and there is some mass, ##M## at the origin at some

$$

ds^2 = -(1 + 2...

Solution strategy for linearized gravity problem]]>

Having trouble with a heat sink in ANSYS NLT]]>

Consider a plane monochromatic wave incident on a flat conducting surface. The incidence angle is ##θ##. The wave is polarized perpendicular to the plane of incidence. Find the radiation pressure (time-averaged force per unit...

Boundary conditions of a plane wave on a conductor]]>