Confusion Definition and 1000 Threads

Still confusion in relativity of simultaneity and time dilation... Hello friend, Still Something in my mind is saying that Relativity of simultaneity is the reason for time dilation even though i had some corrections in my understanding by posting various threads. Well,let me use Einstein's...

I having trouble understanding the difference between parallel and orthogonal in relation to finding the relevant line or plane equations. Example; Determine the vector and Cartesian line if: a) passes through (2,1,-3) and is parallel to v=(1,2,2) What would happen if it was...

This is an extract from my book ... " We define the potential V at any point in an electric field as the potential energy per unit charge associate with a test charge q0 at that point: V=U/q0." I don't know why did the book bring the test charge q0 now in the frame. Shouldn't the potential be...

Homework Statement I am a little confused about the concept of tension as it relates to pulleys. I am studying torque right now, and it says in the textbook that the tension in the rope around a pulley produces a torque that causes the pulley to turn. I don't fully understand this. I thought...

I have a confusion regarding expressing operators as projectors in Schrodinger and Heisenberg pictures. Please help. Consider a two-state system with |1> and |2> We know that e.g. a raising operator can be expressed as: \hat{\sigma}_+=|2><1| But here's my line of thought: In the...

This is an abstract of my book " Potential energy is always defined relative to some reference point where U=0. Therefore U represents the work that would be on the test charge q0 by the field of q if q0 moved from an initial distance r to infinity. If q and q0 have the same sign, the...

Homework Statement Find the most probable kinetic energy of an ideal gas molecule. Homework Equations v=sqrt(2RT/M) where v= most probable velocity k= Boltzmann's constant T= temperature of the system M= molar mass of the gas Maxwell's formula of...

Assume for some real number L and c \displaystyle\lim_{x\rightarrow c} f(x) = ∞ and \displaystyle\lim_{x\rightarrow c} g(x) = L We must prove \displaystyle\lim_{x\rightarrow c} [f(x) + g(x)] = ∞ Let M > 0. We know \displaystyle\lim_{x\rightarrow c} f(x) = ∞. Thus, there exists...

I don't quite get the significance of the delta limit definition, if n>N and |sn−s|< ϵ , why does the limit converges does this simply means that there exist a number ε such that if n is great enough it will be greater than s by ε? But this doesn't make sense, because s is the value...

Hi guys, I'm a bit confused. The initial motivation for including dark energy seems to be: "The Friedmann equation requires a flat universe to have a mass/energy density exactly equal to the critical density. Yet, observationally, including both the baryonic and dark matter, we can only find...

Hi, I'm a bit confused by induced drag on an aerofoil and hoping somebody can clear it up for me. I understand that as air slips around the edges of the wing due to the pressure differential between the top and the bottom surfaces, the angle of attack at the ends of the wings is...

What qualifies for being called a fundamental quantity and having its own fundamental unit? For example length is considered fundamental quantity and it has a unit of meter. But Area isn't considered fundamental. Is it because we know area can be CALCULATED by multiplying the length of the two...

I am a bit confused over something that should be relatively easy to research , however, I am having a hard time finding a direct answer to my question. When finding the extrema of a function , we find at what points the first derivative is 0 or undefined .. with the stipulation , if I am...

I am confused about the counting of degrees of freedom. Yes, I know that it is the number of vectors which are free to vary. But that definition gives way to different interpretations: (1) the number of data points minus the number of independent variables. This seems to be the basis of the...

Hi gang, I am hoping you can clear something up for me. When evaluating the potential of a solid sphere, I find myself confused about the volumes used such that, \phi = Q \int_{\infty}^R \frac{1}{V_1} r^2 \sin(\theta) \, dr \, d\theta \, d\phi + Q \int_R^r \frac{1}{V_2} r^2 \sin(\theta) \...

I was helping my cousin with his homework when i came aacross this problem... I can easily differentiate b/w 3.5 ( three point five) and 3.5 ( three dot product five) when they come in different situations.. but there was this equation written which had the term 3.5. I interpreted it as decimal...

For amperes law it is stated that: ∫Bdl=μIenc My confusion is that B is that for example here now on Earth if I have a compass. It interacts with a the magnetic field of the Earth and points north. There is no I-enclosed yet there is still a magnetic field? Also another Amperes Law...

In calculating the electric field bw two parallel plate i.e a capacitor I encountered a problem :where to take the Guassian surface..When I consider the Guassian surface.a cube bw the two plates Electric intensity becomes 0..But when I take the Guassian surface with a portion of capictor inside...

Notation confusion; ## |\pi N; I, I_3 \rangle ## states In my book it says for the ##\pi N ## state: ##|\pi N; \frac{3}{2},\frac{3}{2}\rangle =|\pi ;1,1\rangle | N; \frac{1}{2},\frac{1}{2}\rangle## firstly, does this mean: ##|\pi N; \frac{3}{2},\frac{3}{2}\rangle =|\pi ;1,1\rangle...

Hi, My question is: 1)When an object falls to the ground, shouldn't the ground exert a force greater than the weight of the object to stop its motion altogether? Because if the forces experienced by the object the moment it strikes the ground are equal and opposite in direction, then that...

I am reading on Object Oriented Programming and I feel a bit uncomfortable with the concept of Encapsulation. And I keep wondering, how can someone 'accidentally' COMPOSE code (to change data) ? We far more frequently accidentally mistype and misspell than accidentally compose code. If a...

I have been trying to understand how PV cells work in solar panels and have become a bit confused, here is what I have read so far: The PV cell is basically a PN junction diode with a conductive connection on the P and N material between this connection there is a load, a lamp for example...

Let f(x) = ax - \dfrac{x^3}{1+x^2} where a is a constant Show that, if a ≥ 9/8 then f'(x) ≥ 0 first problem when taking the derivative in the solution they seem to have jumped a step which I don't see how: f'(x) = a - \dfrac{3x^2(1+x^2) - 2x(x^3)}{(1+x^2)^2} = \dfrac{a + (2a - 3)x^2 + (a...

In a proof showing that the vector space of all functions from a metric space X to the complex numbers C is complete under the supremum norm, there was a line near the end that i was confused about. starting here: \(sup|f - fn| \leq liminf_{m \to +\infty} ||f_n - f_m|| \) the next step then is...

1.http://imgur.com/d2lf8sa 2. V=IR 3. I feel like the answer should just be .012 because 1.2/100. Apparently that is wrong. If that is truly wrong. I also found I3 to be 3.25mA because 3.9 volts in parallel and V=IR

Homework Statement Scientists want to place a 2900.0 kg satellite in orbit around Mars. They plan to have the satellite orbit a distance equal to 1.6 times the radius of Mars above the surface of the planet. Here is some information that will help solve this problem: mmars = 6.4191 x...

I was looking at the header of MHB and I suddenly thought... wait! What does it mean?! I mean, it says:$e^{i \pi} + 1 = 0$ Now, I understand that if you calculate $e^{i \pi} + 1$ that you get 0. But you can also rewrite it as:$-1 = e^{i \pi}$ But how is that correct? Isn't $-1$ multivalued...

Can anyone explain proper time with a simple example analogous to real life please? I am having a problem understanding it. Thank you

Hey guys ! I am confused when textbooks say that P (pressure), V (volume), T (temperature), n (moles) or any combinations of these be CONSTANTS. Especially when it comes down to the three gas laws. I don't understand what some variable being a constant means :( and hence the immense confusion...

the speed v of sound waves in a gas can be express in terms of the pressure p and the density q (mass per unit volume) of the gas, as v=ap^bq^c, where a, b, and c are dimensionless constants. The dimensions of pressure are m/((LT)^2). What must be the values of b and c. I am confused on...

Hi, I'm reading about the Born-Oppenheimer approximation for a solid and they're doing the formalism of it. They say that we can basically consider the ions stationary with respect to the electrons because they move so little and so slowly in comparison to them. They say that ##R_i## are the...

Dear All, I am basically from Bio background and doing research in Insect Physiology as Phd. Currently I am given a task to generate artificial insect songs using a software. I did it with 3 v Noise stimuli(1.5 peak to peak) and fed it to amplifier and I heard it on Amplifier. So now the...

I'm a little fuzzy on the meaning of the angular momenta in electrons. From my understanding, the orbital angular momentum of an electron can have integer values of h-bar and the intrinsic "spin" can be 1/2 (and both can be positive or negative). How does this relate to the energy of the...

So here is my question, I understand how to derive the cosine rule from, both triangles acute and obtuse. My problem is the 3 formula you get from this equation. When I derive from a triangle I get the formula: c^2=a^2+b^2-2abcos∅ so how do you derive the other two formula, I read that...

Hello! I am currently trying to get things straight about Lie group from two different perspectives. I have encountered Lie groups before in math and QM, but now I´m reading GR where we are talking about coordinate and non-coordinate bases and it seems that we should be able to find commuting...

Sorry for disregarding the template; I'm not really working out a homework problem as much as just trying to follow the reasoning in the text. I'm working through the first chapter of Quantum Mechanics, McIntyre, and I'm a little bit confused by the following. The text introduces bra-ket...

Of course the answer is 9. But my question is, some sources say this is written ambiguously. as in, 6/(2[1+2])=1 or 3(3)=1 Why do some people say one needs to evaluate what is effecting the parenthesis before dividing from left to right? I don't see anything in order of operations that...

Homework Statement A sphere rolls from rest down a slope without slipping. Show using energy considerations that the speed of the sphere once it reaches the bottom is V = \sqrt{\frac{10gh}{7}} Homework Equations mgh = \frac{1}{2}mv^{2} + \frac{1}{2}Iw^{2} The Attempt at a Solution...

Hello everyone! I've been thinking about this for a little while and haven't been able to come up with a satisfying answer yet, so I'm asking you guys. I've heard about things like solar sails, where the light from the sun would be used to push something to somewhere. I also heard...

Homework Statement I've been set an assignment and I'm struggling with one question in particular: Homework Equations 'Use the following data and plot the graphs for a point charge' 'Plot graph of E against r^2. Interpret the graph to describe electric field strength and electric...

In the book Mathematical Methods for Physics and Engineering by Riley, Hobson, and Bence, I came across an equation I just can't seem to understand. In the chapter on tensors, they derive the equation for a Christoffel symbol of the second kind, \Gamma^{m}_{ij}=\frac{1}{2}g^{mk}\left(\frac{...

So I ran into residue theorem recently and found it to be pretty amazing, and have been trying to get some of the more fundamental aspects of Laurent series and contour integrals down to make sure I understand it properly, but there's still one big aspect that keeps confusing me majorly...

I have some doubts regarding Current Flow and Capacitances... I Read this somewhere.. " an electrochemical cell supplies energy to move a charge from its low energy, low potential terminal to the high energy, high potential terminal. In this sense, the cell supplies the energy to establish...

Hello Forum, when a camera is focused at "infinity", everything from infinity on is in focus (acceptable). How is that possible? Every plane that is not in perfect focus has a certain circle of confusion that gets larger (more blurring) as we move away from the best focus plane... Also...

Hey, I'm slightly confused on a part of the process of Quantum Key Distribution (E91 protocol). I have something which tells me how Alice would send a message to Bob. An atomic transition from an outside source would produce 2 photons both with the same circular polarisation. One of these is...

Hello! I came across with something that confused me while studying the book and I need some help. In section 7.3 , equation (7.3.4) should have the drivative of ε(x) in order to "vanish when ε(x) is constant" . But in the lines before this expression he says that the variation of action...

Homework Statement We start with an ideal gas confined to half a container. Then, without heat flow, the gas flows into the other half as the partition is punctured. Find the new temperature after the expansion. Homework Equations Since there is no heat flow, I assume the process is...

Homework Statement This isn't a specific question, more of a general one: Suppose there is a cylinder of mass m that is rotating in the positive clockwise direction with initial rotational velocity \omega_0, and radius R. Then, suppose this rotating cylinder is placed on a surface with...

I'm looking at the explanation for single slit Fraunhofer diffraction, in particular the location of the intensity minima. a is the slit width, lambda is the wavelength and theta is the angle. By dividing the slit into two parts and viewing the wavefront as a sum of many small sources i can see...

Imagine i have a particle in the xy plane rotating in a circle around the z-axis at a constant angular velocity. The angular momentum is r cross p which would give me a constant value at all times, there is no change and it's conserved. However if I was to move the rotating particle higher up...