Thanks]]>

Proof Cos (A-B) - tan(A-D) = (2cos A)/(sin 2A + sin 2B)

Cos(A-B) = cosA cosB + sinA sinB

Tan(A-D) = (Tan A - tan B)/(1+Tan A Tan...

How to prove this trigonometry equation?]]>

One could say, well they don't experience time, but we do. Okay, but since their...

Photon states should not evolve?]]>

I was wondering:

Since the mind works on electrical signals, it must work on binary codes, because there is electrical signal or not. If so, is the only thing that distinguishes us from a computer the length of the "bit"?

What do you think?

Thanks.]]>

a) Show that a topological space can't be both a 1-manifold and an n-manifold for any n>1.

If a topological space were both a 1-manifold and an n-manifold, then every point would have a neighborhood...

Manifold questions]]>

Hello to everybody, i just arrived at PF and I would like to know if i may set a couple of questions. First: It's possible for paired electrons to interract if one of them (or the two of them) is (are) in a black...

Conditions for paired electrons]]>

What if the actual force for a newton was different?]]>

I have found out that in the future we might have quantum computers, which will be more powerful than today's computers. Instead of trying every option available to the computer, quantum computers will be able to try many different possible solutions at the same time. What would be some...

Quantum Computer advantages]]>

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using nodal analysis

https://imgur.com/a/UNEDH

the excel sheet is the matrix i set up then...

Nodal Analysis and matricies]]>

Figure 23-30 shows two nonconducting spherical shells fixed in place. Shell 1 has uniform surface charge density +6.0 µC/m2 on its outer surface and radius 3.0 cm. Shell 2 has uniform surface charge density -3.8 µC/m2 on its...

electric field inside non conducting spherical shell]]>

I don't understand something about torque. I can prove every definition about rotational motion if I assume that a point mass is moving in a circular motion.

and if I also define a point of rotation I dont need an object to rotate in order to have...

Torque: Point of choice]]>

For example, Computer 1 simulates the front of a statue. Computer 2 simulates the back of a statue. Computer 3 simulates the birds eye view of a statue....

Is there such a thing as multiple simulation?]]>

Conductive fluids and magnetism]]>

Find the average y coordinate of the points on the semicircle parametrized by C:[0,##\pi##]-->##R^3##,

##\theta##-->(0, a*sin##\theta##, a*cos##\theta##); a>0

Average y coordinate of points on parametrized semicircle]]>

This is not about it's mathematical significance. Get your inner designer on!

- Each member is allowed to post one equation
- The equation can be completely made up...

Contest: Equations as Art 2017]]>

in the picture , we can see that the number of equipotential drop , Nd = 18 . I am not sure why at point a , nd = 1.75 , how to get that ?

In my opinion , the...

Seepage of soil (flownet)]]>

I am planning on building my first Focault Pendulum(As a physics projject for school) and I have a few questions. I am going to purchase a cable(it needs to be smooth and friction-less around 7 feet), I also am going to need to...

Foucault's Pendulum Recreation for Physics Project]]>

I need to find the peak voltage of the ac current produced by the sensor connected to the alternator on my motorcycle. The workshop manual recommended a peak voltage adapter which goes on a multimeter.

I don't want to buy this expensive thing.

I was wondering since...

Multimeter Peak Voltage Reading]]>

My question is, how much dark matter (any of mass, volume, density, etc) would we have to have in our solar system for us to detect it? My guess is that we would detect the dark matter through gravitational lensing or the perturbation of planetary orbits.

On previous posts about dark...

Dark Matter Size to be seen in our solar system]]>

Magnitude-5.3 earthquake hits Japan's Fukushima

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

Clocks...

Einstein's definition of time]]>

Two New Zealand Earthquakes]]>

the yeld of the bomb was supposed to be 5 Mega Tons but it was 15

i have 2 questions

1) why they usd LiD as a fussin full instead of normal deuterium

2) why did the lithium acted...

H-BOMB ''castle bravo'' -- Why was the yield so high?]]>

Is this point of contact an inertial frame?]]>

In wiring an outlet,...

Use of pigtails for wiring outlets]]>

Let's say we can travel at light speed, we send a crew to Proxima Centauri, & it's exactly 4 light years away. They explore for exactly one day, then return.

1. Since it takes 4 years for light to reach it & 4 years...

Light & Time]]>

$$u = (\epsilon/2)E^2 + (\mu/2)H^2$$

One of the differences between the classical electromagnetic theory and the real world is that in classical EM all charge and current density, (ρ(

Correction to the field energy due to the existence of discrete charges]]>

Our Beautiful Universe]]>

How do we determine a specific force mentioned in a question to be conservative or non-conservative?

Conservative force is a force whose work done does not depend on the path that is taken while doing...

How to differentiate b/w a conservative/non-conservative force?]]>

$$V(r)=\begin{cases}

& 0\text{ $r<a_0$}\\

&V_0\text{ $a_0<r<a_1$}\\

& 0\text{ $r>a_1$}\\

\end{cases}

$$

$$...

Boundary conditions with l=0]]>

Anyone with references please

Thank you]]>

Why use i to represent y vector ?]]>

Brainstorm: Is absolute zero relative]]>

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Components of the equivalent moment at a point]]>

I use Scientific Workplace to write down math equations and also to create documents involving mathematics and to do calculations. Although most people use it for writing science articles, I've found it extremely helpful for whatever little bit of mathematics I do.

I face a problem when I...

Sharing latex code...]]>

1) Provide a clear statement of purpose

Just a "Wow. Look at this!" factor: 180,000+ people evacuated from below the tallest dam in the USA.

Just about everyone is now...

Oroville Dam]]>

Turns out that Zoobyshoe beat me in posting about this in another thread, so he will officially be known...

Weird News Compilation]]>

Also, it takes me a while to grasp the material, and I am always behind, but I do well on the quizzes. I am worried for my exam. Can anyone provide any advice? Please?

Thanks.]]>

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I know that there are two eigenstates of the operator C:

|B> = (1 0) as a column vector with eigenvalue 1

|R> = (0 1) also a column...

More questions about 2 state system measurements]]>

I am curious about an apparently small difference while inserting an image in a post .

Recently while helping a member I inserted an image here https://www.physicsforums.com/threads/pulley-constraints-problem.926268/#post-5846690

This is what I do . If I want to put an...

Different ways of inserting image in a post]]>

Let G be a topological group acting continuously on a...

Quotient maps, group action, open maps]]>

I was thinking maybe small box with a rod coming out of...

Make a very simple mechanical time delay?]]>

Solve the equation

$$cos(\pi e^z) = 0$$

I am not allowed to use the complex logarithm identities.

$$ \cos z = \frac{e^{iz}+e^{-iz}}{2} $$

$$e^{i\theta}=\cos\theta+i \sin\theta$$

Complex cosine equation]]>

Introduction to Perturbative Quantum Field Theory

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Continue...

Introduction to Perturbative Quantum Field Theory - Comments]]>

App suggestions for practicing mathematics?]]>

How much volume or mass of space does one need to see appreciable effects of dark matter where general relatively seems to break down? What is the critical volume of space at this time where people can see the effects of dark matter and where they cannot? Is there a spatial scale smaller...

What spatial scales does dark matter become significant?]]>

On a (very) recent vacation, I took a cruise aboard the MSC Orchestra, almost 300 metres long and almost 100,000 tons.

During medium-high seas, I lay in my bunk (midship, near top deck, 120 feet up) and felt...

Resonance in large objects, say a cruise liner]]>

First scenario: I position myself very close to the pivot point and push, the rod rotates and I move...

Me, A Rod and A Table With Little Friction]]>

I will be going back to uni next year to pursue an engineering degree and I'm torn between mechanical and mechatronics engineering (specifically a mechatronics + CS double degree). I've looked at the units in both courses and (almost) all are interesting to me. On the one hand ME is a...

Questions for Mechatronics students/graduates]]>

Intermediate Math Problem of the Week 9/18/2017]]>

GRE : 310/340

168Q 142V 4AWA

TOEFL: 104/120

22R 27L 26S 29W

I am applying for graduate schools in the following universities. Is the list sufficient? Any suggestion is most welcome.

The list is not priority-wise....

Suitable list of schools for an MS to apply for a PhD program in Optics]]>

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First part is easy . Area of the triangular loop is A = (1/2)(2R)(R) = R

Induced EMF in loop ABC = Rate of change of...

Induced EMF between two points]]>

This is a linear algebra problem. Sorry I wasn't sure it to put this on precalc or here.

Consider two systems of linear equations having augmented matrices [A:B_1] and [A:B_2] where the matrix of coefficients of both systems...

Is it possible for [A:B1] to have a unique solotion..?]]>

In a not so near future, (that is fictional, but meant to be rather hard, realistic) could people have a life similar to ours, with all the recent developments...

Everyday life in SF]]>

Many Worlds Interpretation]]>

Somewhat Complicated Thermal Problem]]>

Voltage potential in PEM electrolyzers]]>

Consider an elastic sphere which is homogeneously charged and suferring an harmonic inflation and deflation.

Is it correct to explain the theoretical result that it does not emmit radiation, even though all of its charge elements are accelerating, as a systematic effect of destructive...

Why a pulsating charged sphere does not emit radiation?]]>

How to prove the correlation between launch angle (<45°) and horizontal displacement.

Independent Variable:

- Horizontal distance

- Launch Angle

Relationship between Launch Angle & Horizontal Distance]]>

Question: A certain amount of oil on the sea surface can be considered as circular form

and the same thickness throughout its surface. At a certain time, the following are noted

Data: Oil is supplied...

Homework question using the chain rule -- oil slick spreading on the sea...]]>

The multiplicity of an ideal gas is given by g(U) = A.U

Prove that the energy of the gas given a temperature T is U = (3/2).N.kb.T

My...

Energy of an ideal gas given it's multiplicity]]>

Best laptop (fast) under 300$-400$]]>

Abstract:

1. The problem statement, all variables and given/known data

A metal surface is illuminated with monochromatic light and it becomes charged to a steady positive potential of 1.0V relative to its surroundings. The work function energy of the metal surface is 3.0eV, the...

Photoelectric effect calculation]]>

Suppose two successive coordinate rotations through angles ##\Phi_1## and ##\Phi_2## are carried out, equivalent to a single rotation through an angle ##\Phi##. Show that ##\Phi_1##, ##\Phi_2## and ##\Phi## can be considered as...

Two successive rotation (Goldstein problem 4.13)]]>

How to study a particle with several features?]]>

Internships, which one is the right one]]>

Need to find the acceleration of the blocks, all surfaces are smooth : https://drive.google.com/file/d/0B5bF4yPQOejoazhWeEgySmtfSnc/view?usp=drivesdk

Pulley constraints problem]]>

"Space and Stuff"]]>

Assume desert 120F hot and very dry air can enter/exit at either bottom around ankles or at top around open...

Optimizing Evaporative Cooling via Sweat in Dry Desert?]]>

A projectile travelling vertically strikes a block and stays in it. The mass of the projectile is 0.20kg and its speed is 3.0m/s at the instant of impact. The mass of the block is 1.3kg. Air resistance may be neglected.

(a) How...

Momentum Involving Height]]>

The Trump's wall is so weak that has to be supported by two cables as is shown in the figure. If the tension over the cables BD and FE are 900 N and 675 N respectively.

(I'LL UPLOAD AN IMAGE OF THE PROBLEM SO YOU CAN SEE IT)...

How can I find the torque/moment of force about an axis?]]>

http://www.nasa.gov/mission_pages/newhorizons/main/index.html]]>

> When a coffee maker is connected to the wall (230 V, 50 Hz) its power consumption is 180 W. The power consumption...

Calculating capacitance from an AC circuit]]>

Describe the energy conversions in a spring undergoing simple harmonic motion as it moves from the point of maximum compression to maximum stretch in a frictionless environment. Focus on points at which there will be maximum...

SHM Energy Conservation in a Spring]]>

A block of mass m rests on an inclined plane with angle o accelerating to the right with acceleration a. The coefficient of static friction is u.

For what range of a does the block remain at rest...

Block on an inclined plane that is accelerating sideways]]>

My real name is Ryan, but you can call me Unix (handle I've had since I was a kid). I'm 27 and have always been a huge fan of anything science. I'm formally educated with a BS in Electrical and Computer Engineering and I work as an Engineering Technician for a small electronics...

Hello Everyone!]]>

Does anyone of you know of an estimate of how many biological species humans have domesticated - I mean everything from silkworm to chicken, yeast, lactic acid bacteria, rye, corn, horse, fruit fly, shrimp, zebra fish and jellyfish - any organism that we bread or culture for a purpose?...

How many domesticated species - thousands?]]>

i know problems of this kind have been posted a lot but i have a few of my own questions please take a look at them thanks

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i am having several conceptual errors in...

Falling pole leaning on a wall]]>

I am boning up on my physics because I was invited to proof-read a friend's book on 'Special Relativity'.

I have a BA in Computer Science, but have been a math/physics groupie for a long time.

My other...

Hello folks. me = physics groupie]]>

Keri]]>

Help me understand how electrical meters work]]>

Observable particles are considered to be on-shell, and as 'asymptotic states' at time +- infinity. Now, in a scattering experiment, I may produce a new particle, which will travel...

Observable particles as asymptotic states...]]>

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In this question,...

Specific heat at constant pressure]]>

Which interstellar "empire" do you like the most?]]>

I suspect the shrinkage limit is wrongly defined here . But , here , shrinkage limit is defined as no volume changes when the degree of moisture is still 100% .

Shrinkage limit]]>