So a number.

For scalars, I agree because they are described by a single number.

But what about vectors? They have...

Definition of Measurement]]>

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X% of the liquid is removed...

Cocurrent diffusion (can't be this hard..)]]>

Public physics moral dilemma]]>

I know this is long, but that is only because this question requires me to be thorough, conceptually I think it isn't difficult. To make it easier to read I

In Physics lab, we were told to...

Effect of mass on skid distance of car experiment]]>

Thus say we create the set of such objects such that A or B (inclusive...

Correct way to understand logical implication?]]>

I try to calcualte inner/outer surface stresses on a pipe submitted to instanatenous temperature variation on the OUTER SURFACE.

I know the Roark's formua giving the stresses but with an instantaneous temperature variation on the INNER...

Stress in a tube due to external radial temperature gradiant]]>

Resistive Ohm's law is famously known as

Is there microscopic version of general Ohm's law of V=IZ?]]>

and

"the uverse is expanding"

my understanding is you cant have both, because to define expansion you need measurable differential on a boundary, thus expansion by definition infers changing...

Infinite vs Expanding]]>

Wednesday, 1 pm EST. You can use the forum for time zone conversion: This post was posted 3:55 pm EST.

While the announcement doesn't have any details, digging a bit...

NASA press conference: Exoplanets around TRAPPIST-1]]>

Given the solar wind has velocity ##450## km s##^{−1}##, i.e. it is slow solar wind, and if the heliopause is ##150## AU from the Sun, how many turns are wound into each ﬁeld line between the Sun and the heliopause? Assume the...

How many turns in the field?]]>

In a parallel circuit, one branch contains two equal resistors of resistance ##R_1## connected in series. The other branch contains a...

Voltage and phase between two branches of ac circuit]]>

Magnitude-5.3 earthquake hits Japan's Fukushima

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

In my book , the author stated that when we do the pivoting , we need to make the element below the leading element = 0 . For example for 3x3 matrix , for the first column , we have to make a11 = max , and make sure that a21 and...

gaussian elimination(pivoting)]]>

And some follow-up news from the Economist:

http://www.economist.com/blogs/democracyinamerica/2017/01/quick-rebuke

In my personal opinion, when I had first heard during the...

US Bans Travelers from Certain Muslim Countries]]>

Intensity of sound is (W/m^2) and is inversely proportional to the the square of the distance measured from the sound source. The noise level of a risiing jet aircraft at the distance of 30m, is 140 dB.

How far from the jet...

logarithm word problem, is there enough info?]]>

When you sell books online, what methods do you use? How much do you pay? Do you use media mail? Flat rate boxes?

I am selling some textbooks I'm no longer using, and I'm kind of clueless about this sort of thing. I've been going to a UPS store that does...

Selling books online and shipping]]>

if planets orbit around suns due to the sun bending space, then why...

how exactly does gravity work?]]>

Leverage and Forces on a Pivot System]]>

Please bear with me, you can skip to the LSS (Long Story Short) line if you do not want to go through the wall of text. But the complete story carries important information regarding my demise :).

After a painful 7 years, I managed to obtain my PhD in Physics. My Thesis and...

I am now a PhD, but feel lost about myself and Science.]]>

Waqaa (hello in Yupik)]]>

Help understanding recent work on "Space-Time Crystal" and TTSB please]]>

Do you imagine any physical reason behing this?]]>

Although velocity decreases due to friction with ambient air, momentum should be conserved and, therefore, it entrains mass.

What is the reason that momentum should be conserved?]]>

I recently came across a blog on schlieren visualization (http://ottobelden.blogspot.in/2010/07/homemade-schlieren-photography-setup.html).

I replicated it with the following: Convex lens (130 mm dia and 350 mm focal length), LED light source (5 mm white LED) and smartphone...

Velocity Estimate from Schlieren Flow Visualization]]>

We are currently searching for a new state theorized to occur in a specific decay process. I know we have to work with data...

Why Monte Carlo Simulations? What do they tell us?]]>

Does the magnetic field produced by a magnet act on itself?]]>

Uncertainty Propagation in Coupled Oscillator]]>

Please...

For physicists, what area do you specialize in (revamped)]]>

About half way in the lecture he talks about the "qubit". In that section he introduces a 2x2 unitary matrix which rotates a vector by 45°. He applies that transformation to the state...

Can someone please explain Scott Aaronson lecture9?]]>

This started with a student confused with statements describing critical temperature for the gas/liquid equilibrium. Some books and sources state it is the highest temperature AT which it is possible to liquefy the gas just by...

Critical temperature, or: Is the supercritical liquid a phase?]]>

I have come across two definitions of eigenstates (and eigenvalues), both of which I understand but I don't understand how the two are related:

1) An eigenstate is one where you get the original function back, usually with some multiple, which is called the eigenvalue.

2) An eigenstate...

Eigenstates & Eigenvalues]]>

Obviously there is a lot of information online, but it always seems rather incomplete.

There also seem to be a lot of books around, but there is always the problem of...

What references do you use?]]>

Why colonize Mars and not the Moon?]]>

x1 + 2x2 = 9 ,

6x1 + 6x2 -8x3 = 1 ,

-3x2 +x3 = 0

Here's a question from my book . I'm asked to find the x1 , x2 and x3 by using the gaussian elimination with pivoting .

pivoting (gaussian elimination)]]>

After being produced in a collision between elementary particles, a positive pion (π+) must travel down a 1.00 km -long tube to reach an experimental area. A π+ particle has an average lifetime (measured in its rest frame) of...

Relativity - Pion]]>

I am given some results of certain experiments with errors and I need to rewrite them correctly in term of significant digits.

The professor explained to us that, for example, 1.12345 ± 0.5231 is...

Significant figures]]>

I'm a bit confused about the eigenvalues of the second quantized fermionic field operators [itex] \psi(x)_a[/itex]. Since these operators satisfy the condition [itex] \{\psi(x)_a, \psi(y)_b\} = 0 [/itex] the eigenvalues should also anti-commute? Does this mean that the eigenvalues of...

Eigenvalues of Fermionic field operator]]>

1 mole of ideal gas with internal energy U= 3/2 RT , expands from initial volume V

.

Find

(a) the highest temperature...

maximum temperature reached by gas in expansion]]>

At time 1:55, Charlie mentions Feynman used to sleep with wives of his undergraduate students.

I never knew about this personal side of him.]]>

As I understand it, a basis for some...

Basis, row and column space]]>

A 0.75-m rod has a uniform linear mass density of λ. A small mass m with negligible volume is attached to one end of the rod. The rod with the attached mass is placed in a container of unknown ﬂuid and after oscillating brieﬂy,...

buoyancy force and floating]]>

Two point charges q and λq located at the points, x=a & x=μa respectively. If the sum of the two charges is constant,what is the value of λ for which the magnitude of the electrostatic force is maximum?

Electrostatic force problem]]>

In a XY - model in two dimensional square lattice. I want to calculate specific heat capacity, <E> and <E^2>. By using the formula:

H = -Jsum(<i,j>)Cos(tetha(i)-tetha(j))

The Metropolis algorithm reads:...

Metropolis algorithm in MC]]>

V+ = 1

V- = 0.5 * Vout

Supply Voltage = +-9

Vin = V+ - V-

At start V+ = 1 and V- = 0, providing us...

A question regarding electronic negative feedback]]>

(i) Current is...

Confused about voltage & current -- Please check my understanding]]>

Are there any other particles besides protons and neutrons (and their

A door ( a rod of length ##L##, mass ##M##) rotates with angular velocity ##\omega## about a point ## H ##, and approaches a stop at ##S##. ##H## and ##S## are along the same line, and separated by a distance ## s ##. Show that...

Angular momentum of a rotating door]]>

Deciding Oxidation States]]>

Curvature of Flat Lorentz manifolds]]>

https://www.physicsforums.com/threads/math-reus-2016.858490/]]>

Classify the following actions based on how they could affect a reaction rate (rate increases, rate decreases, rate is unaffected) and provide a brief explanation as to why:

- Add a catalyst
- Decrease the concentration...

Factors Affecting the Rate of Reactions]]>

[A(

What is the physical significance of Bell's math?]]>

A triangular prism of mass

a Newton's law question which is too hard for me]]>

Thank you.]]>

Here is a brief description of possibility theory from a recent article behind a paywall.

It seems Josephson after winning the nobel prize went beserk and pursued transcendental meditation and spoon bending; I also have the book by Robin Ticciati on QFT for Mathematicians on my shelf and I know that he...

Josephson's going astray of mainstream physics]]>

Qubit mixed state density matrix coordinates on a Bloch ball]]>

The title "Speed of time" is the best I can come up with. We know that time isn't constant, rather it depends on the speed at which we move as well as the gravity we are subjected to (see https://en.wikipedia.org/wiki/Gravitational_time_dilation for a reference to the...

Speed of time]]>

A 12 Volt lead-acid car battery, engineered for "up to 500 or more charge/discharge cycles," has a rating of 330.0 Ampere-hours. It sells for $ 262.00.

Part B: The battery has a mass of 32.7 kg. What total mass of such...

Total Battery Mass for Equal Efficiency]]>

Rate Laws]]>

that the potential energy is in the lifted mass.

This cannot be. Consider the case of two perfectly rigid spheres, isolated in...

Where is potential curvature stored in GR?]]>

Let f : R → R

Conditions on f such that the anti-derivative F is periodic?]]>

Are many physicists not fluent in the language of physics?]]>

1. Are diabetes and hyperglycemia the same?

If not,

a) What is the difference?

b) Our current treatment seems to be against hyperglycemia. What are we doing for diabetes?

If both are same,

a) What are the ill effects...

Hyperglycemia and is treatment]]>

The question is:

How do I find all the reactions? I haven't worked with a similar problem before, so I'm kinda confused. Hope someone will help!

Thanks from now.]]>

http://www.sciencegeek.net/tables/AtomicRadius.pdf - Where He is slightly smaller than H

http://intro.chem.okstate.edu/1314F00/Lecture/Chapter7/ATRADIID.DIR_PICT0003.gif -...

Does Helium or Hydrogen have the greater atomic radius?]]>

Design of CT with ferrite core for reverse operation of CT]]>

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The temperature is reduced so much, that the quantum wave states overlap and become one single object.

So what are the properties of this object? Is it...

Bose-Einstein Condensate Properties]]>

a) {1}

Number of Subsets: ##2^1 = 2## (∅, {1})...

Sets, Subsets, Possible Relations]]>

I need to research Hess' law, but I can't find a simple explanation. I know that the enthalpy change between the reactants and products is the same as the enthalpy change between the reactants and something else, and between...

Hess's law explanation]]>

Trouble Understanding Suborbitals]]>

I have tried the integral below with Mathematica and it gives me the following solution:

##\frac{d}{dc}\int_{z^{-1}(c)}^{1} z(x)dx = -\frac{c}{z'(z^{-1}(c))}##

I am not quite sure where it gets it from...I think it can be separated and with differentiation the first part will be zero:...

Integral with an inverse function limit]]>

2^(t-1) * 6^(t-2) = 20,000

I have no idea how to solve this, although I do understand the basics of logarithms]]>

This isn't real, but say that a vehicle travels from 0 to 200 feet linearly at a

Time for Non-Uniform Acceleration]]>

dt = measured time interval between left...

Sound-bearing equation]]>

Could anyone offer some insight on this topic?

In the case of a physical system composed of multiple particles, there is only one single wavefunction that depends on the three position variables of each particle and the parameter time t. For example, in the case of 2 particles, we...

Two particles: Entangled State vs Non interacting State]]>

"Adding fuel in a diesel...

Air fuel ratio effects in diesel vs. petrol engines]]>

Consider two charged particles 1 and 2, each of them able to translate (move from place to place) and to spin.

I can not completely think of relevant equations at the moment.

Defining magnetic interaction between charged particles.]]>