Explanation Definition and 961 Threads

As I understand it PIM is always present when we have 2 or more RF signals traveling in a medium where we have dissimilar metals (like a coax cable attached to a connector). Further, it seems that the intermodulation is highest at IM2 product and weakens as the IM product increases. The most...

I'm taking an online coursera course and the guy is explaining limits. He doesn't really explain why he does this numerator thing.

ice skater with mass = 80 kg moment of inertia (about her central axis) 3 kg m2. Catch baseball with outstretched arm 1m from her central axis. Ball has mass 0.3 kg and v0 = 20 m/s before the catch. V system ( skater + ball ) after catch = 0.0747 m/s Question : b. Angular speed of the...

Hi All, Recently, in my earlier thread, I asked about the symmetry of Lorentz Factor (where +V == -V). I had several pointers about how to handle this (Thank you all those). However, it seemed unanimous that there was no explanation beyond the equation itself (math or physical). Also, I...

Hi all, I have what I believe is a simple physics question. I was burning a sprig of incense in my apartment, and noticed that the smoke was rising from the burning section perfectly straight up into the air for a good meter, and then started to dissipate into the air. I know that a gas will...

Wouldn´t it depend on the gun and the speed of its "bullet"? Not sure what this question refers to.

According to Feynman's lecture in physics an electron doesn't fall on the proton because of the uncertainty principle. Now, if electron falls on the proton, it's position and momentum can be known so it leaves some place for it to move. But uncertainty principle is applicable for all particles...

Happened to pass someone wearing a t-shirt today with the logo: F/C^2(sqrt(-1))PV/nR Could you explain to me what this means? Thank you

I just couldn't understand how does augmented matrix deduce inverse of a matrix. I mean what is it in the row operation because of which we get the inverse of a matrix. I just don't want to learn the steps but to understand why it works. Thank you.

Hello, Here is a quote from the Wikipedia article 'Principle of relativity': http://en.wikipedia.org/wiki/Principle_of_relativity i'v added a string of asterisks around the word 'A consequence'. i feel that there is not enough elaboration about this 'consequence' thing. Was the consequence...

Why are things quantized? Just say for example that energy increases continuously. If this is true, than objects would accelerate to infinite speeds when falling to Earth because they are falling through an infinite amount of equipotential surfaces, all with values equal to 9.8. And an...

Hi all,I have been struggling mightily through Purcell's book on Electricity and Magnetism, but chapter 5, which deals with the SR explanation of magnetism has me somewhat confused. Suppose we take the following scenario: In the Lab frame, F, electron 2 (e2) is moving towards the right...

I saw a thread that asked the same basic question as I'm asking, but the explanation was beyond my current knowledge. Please consider answering my question as if you were being interviewed for a Discovery Channel special and had to make it comprehensible for a general audience. Thanks! For me...

I hope this is the most appropriate place for this question... So the PF posted this cool set of pictures yesterday on FB. Hopefully the link below works. It shows how some really big things "look" similar to some really small things...

While trying to understand special relativity, i came across the following explanation several times: Imagine a train moving at c/4 from left to right. If a person A, inside the train standing near the back of the train, flashes a light, the light is supposed to travel in the direction of the...

Hey all, I realize a question on this topic has been asked elsewhere, but the links to references they use seem to be dead, so I'll press on! I'm reading some introduction to antenna theory and I've often puzzled on the equation: A_{eff} = \frac{\lambda^2}{4\pi} which relates the effective...

I know this should be easy to understand but I just need a little clarification on the last part of my answer for this problem: If three distinct dice are rolled, what is the probability that the highest value is twice the smallest value I started this problem with the understanding that there...

This paper, http://arxiv.org/abs/1503.03859, suggests a possible explanation for hemispherical anisotropy in the CMB based on non-commutative space time.

Hi, Is there a mathematical equation that for itself can explain, or be deducted from it the wave-particle duality? I mean something that connects that 2 concepts in physics equations? sorry if my english isn't very good.. PD: If you can recommend me a paper or a book that describes and...

Homework Statement See attached image. Homework Equations Left- and right-handed limits. The Attempt at a Solution I know lt (t -> 12-) f = 150 mg and lt (t -> 12+) f = 300 mg, but I don't know how to explain these numbers. I'm assuming that measurements are taken and that this graph is...

Homework Statement This is my prof's explanation of Diels-Alder ... below is the mechanism and some resonance structures he drew to explain the concerted movement of electrons to the class ... Homework Equations Nucleophiles attack electrophiles. Electrons in HOMOs go into LUMOs. The...

Homework Statement By How much does the pressure in a cylinderical jet of water 4mm in diameter exceed the pressure of the surrounding atmosphere if the surface tension of water is 0.0718 N/M? Homework EquationsThe Attempt at a Solution ΔP= σ/r=0.0718/2*10^-3 , This is the answer I have but I...

Hi, I'm trying to wrap my head around the derivation of the wave equation and wave speed. For starters I'm looking at the derviation done on this site: http://www.animations.physics.unsw.edu.au/jw/wave_equation_speed.htm I could maybe explain what I understand at this point Given a string with...

Example video I made a few years go: Note that most of the air interacting with the ball flows around the ball, as demonstrated near the end of the video where a tube is used to prevent flow around the ball, causing the ball to shoot upwards. The main point of this post is the explanation...

Homework Statement I'm reading through Taylor's Classical Mechanics, and I am confused by one sentence in section 10.6 The image he is referencing is this while the text is here. Specifically the statement "the gravitational torque is clockwise" Using the right hand-rule, I run my...

Hello everybody, I'm a final year student in mechanical engineering. For my final year project, I'm designing a spring system to store energy when stopping a hand wagon and use this to boost the wagon when starting. This involves a pinion attached to the axle of rotation for the wheels, and a...

Hi I am trying to get a simple grasp of the concept of a group generator and group representations. As ever wherever I look, I get very mathematical speak definitions such as: "A representation is a mapping that takes elements g in G into linear operators F that preserve the composition...

Homework Statement I'm studying the equilibrium of I2 and its distribution in two immiscible liquids (varsol and aqueous potassium iodide). Since I2 is non polar; it will "prefer" to be in varsol but since KI (aq) is an ionic salt solution, iodine will also dissolve to give the I3- ion. When...

Hi, I am working on constructing a thermal circuit where I am using the concept of natural convection from a vertical hot plate in the shape of a DVD. In order to calculate the Grashoff number, I have to use the characteristic length. What should I take as my characteristic length? The disc OD...

Hi everyone , i was wondering for a while to get a satisfactory proof of the equation : e^i*pi = -1 yes , i know it can be derived from euler's formula ... which is e^i*x = cosx + isinx ( which can be proved using differential calculus ) so, e^i*pi = cos(pi) + isin(pi) ( which leads to the...

De broglie proved that angular momentum of particle can not have any value it has to have the value of nh/2pi and that's what Bohr's second postulate says but according to bohr that n in the formula is principal quantum number but according to de broglie n corresponds to number of waves.So why...

Can you explain me mathematically one particle in many places. Thanks

< Mentor Note -- The OP's question was in the thread title. They have been advised to please make more detailed and clear thread starters > thanks

I have an online homework question and my classmate told me the answer but I would really like someone to explain to me how that answer was determined. I do not understand. Q: Consider the electric field observed at a point O that is far from the two slits, say at a distance r from the midpoint...

Hello, I am new to electronics and am having trouble understanding this formula for capacitance: Could someone please break this down into layman terms? Interestingly π appears? I'd like to understand why that exists in capacitance. Thank you all in advance!

Can someone explain to me why voltage from Megger(500, 1000V) isn't that dangerous, why current is small? Thanks.

I have been learning GR since past few days and have come across the following problem. I just can't get what result exactly the equation wants to be deliver:olduhh:. Please help me out... Please a bit theoretical:) How do we describe Gravitational field through Einstein's field equations...

Homework Statement A rod is made up as shown [pic attached] Both have same cross-sectional area. Ep and En are Young modulus. The rod breaks when total extension = 3.0mm Greatest tensile stress that can be applied before rod breaks? Homework Equations Young modulus = stress / strain The...

Homework Statement Hello! For example, there is a 'cash flow' of 80 000. Discount rate is 13%. Then to find discounted cash flow I need to do the following: 80 000 / 1.13 = 70 796.46 If, for example, the same 80 000 is a gross amount and I need to find net one with the same rate of 13%, then...

All explanations of Josephson effect I have read so far are based on Ginzburg–Landau theory. There seems no explanation based on Schrodinger equation. Why? While an explanation of Josephson frequency of 2eV/h seems not difficult to envisage, the major problem, I guess, should be with electron...

Homework Statement Image: http://puu.sh/ca93V/7eb9abf342.png Homework Equations Ok I know to use this guy http://puu.sh/ca95c/ad0155a4d6.png Which then turns into this http://puu.sh/ca96W/68802e045c.png (except from .5a to 4a, not 0 to a)The Attempt at a Solution I get lost on trying...

Hi all, I understand the concept of red shift, and how it helped to explain how the universe was expanding and that most of the observable universe is moving away from us. It happens due to the wavelength of light increasing due to the expansion of space. As I understand it, it's not know how...

I am looking for a Book in which Solitons and Skyrmions are easy explained. I want to understand them for Solid State Physics. Thank U Abby

So I have an issue understanding how to compute a matrix using the Minkowski metric as a null (read light-like) spacetime vector. As best I can understand it, it is a vector which has all velocity in the spatial components and none in time. Also, would a vector that transcends the speed of...

Hi everyone, Could someone please offer a clear explanation of how electron scattering can be used to provide evidence for the existence of quarks? Thank you!

I read that the top quark is "the smallest quark, which means it is the most massive". How can it be the smallest and yet the most massive?

I have literally spent all day reading and am still very much in the dark. First off does anyone have a link to detailed blow by blow account that doesn't assume an understanding of advanced maths and physics concepts and notations but will actually address the issue in depth? Here are...

Is there a theoretical basis for the spin of the nucleus of an arbitrary atom? I'm looking at this website: http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/nspin.html

I kind of know what limits are, or at least believe I do: I think that a limit of a sequence is just an approximation/intuitive way to finding a number (if it exists) to which a sequence tends. For example, 1, 2, 3, 4... tends to +∞, while 1/10, 1/100, 1/1000... tends, "obviously/intuitively"...

I know how the canal rays are produced. As I looked from wikipedia; "The process by which anode rays are formed in a gas discharge anode ray tube is as follows. When the high voltage is applied to the tube, its electric field accelerates the small number of ions (electrically charged atoms)...