Confused Definition and 1000 Threads

Hey guys! I find it confusing to prove "mv^2/L", the average force acted by the air molecules on a wall in a box. My textbook tells me an assumption "the time during each molecules colliding with the wall of the container is negligible compared with the time elapsed between successive collision"...

To make the confusions both concise and explicit, I will put down some incorrect calculations, and ask for corrections Take the Lagrangian KE - PE = T - V Action = S=∫ L dt (with given limits) Principle of least action: δS= 0: S(t1)-S(t2) =0 if t1-t2 is small (using the (.) as function...

So I was told by my teacher today that I am doing the bogoliubov transformation wrong because I'm supposed to have 4 different vectors, i.e Instead of Ak and Bk A1k A2k and B1k B2k I'm wondering how this makes sense. I've seen papers with 2 different vectors and their complex...

Really confused, need advice :( Hi, Most of you have much more experience than me, you went through the decision making process before uni so I really hope that you can help me here. I am in my final year of high school, got about 10 month left before my final exams. I am doing extremely well...

In many of my physics classes we have been using Taylor Expansions, and sometimes I get a bit confused. For example, I feel like different things are going on when one expands (1-x)^-2 vs. e^(-Ax^2), where I just have some constant in front of x^2 to help make my point. To keep things simple...

Integrals...look easy but I'm still confused :( Homework Statement evaluate the integral ∫(36/(2x+1)^3)dx Homework Equations dx^n/dx = nx^(n-1) The Attempt at a Solution ∫(36/(2x+1)^3)dx = 6ln[(2x+1)^3]/((2x + 1)^2) ( I know this is wrong, but why??) ∫(36/(2x+1)^3)dx =...

I am revising on sketching curves. But I am very confused about the following even though I have become very good at sketching graphs. An example from the book is: Given that: i) f(x) = x^3 ii) g(x) = x(x - 2) Sketch the curves with equation y=f(x + 1) and g(x +1) I don't...

I first thought that electromagnetic induction disobeyed the law of conservation of energy since there is another current created by another current by changing it (AC). but then there is Lenz law that says when you have yourself an current and also a changing magnetic flux, there will be an...

i'm trying to prove - or disprove ! - the following : -\ln x\frac{\left \{ x^{1/n} \right \}}{2n^{3}}=\frac{1}{2\pi i}\int_{-i\infty}^{i\infty}\frac{s}{\left((ns)^{2}-1\right)^{2}} x^{s}ds where \left \{ x^{1/n} \right \} is the fractional part of x^{1/n} for x\in \mathbb{R}:x>1 , n\in...

hello world long time no see..actually I've been very confused with this resting membrane potential I've sooo many questions but i'll only ask one question for now .at rest the membrane of nerve cell is permeable to potassium , potassium goes outside the cell along its concentration gradient...

Hi, I have a question (or maybe more) about special relativity. I'm reading The Fabric of the Cosmos by Brian Greene right now, and what I got from one of the sections is confusing. I might be understanding it wrong, or maybe what he's saying is wrong, or maybe it's just right. So this is what...

Homework Statement An appliance box has a square base with sides of length L, and has rectangular sides with a height of 3L. The top of the box is missing. The box is made from cardboard of uniform thickness and density. What is the height of the center of mass of this open box, with respect...

hello! I was going over some questions on the vcaa site and there was this question in the year 2006 physics exam two. It was question ten. Here's the question (page 7 question 10) http://www.vcaa.vic.edu.au/Documents/exams/physics/2006physics2-w.pdf The answer said that in order to find...

1. If the statement ph=-log([H+] is true, then how come a solution can be acidic when carbonate is present? I have been told that even if carbonate does not accept H+ the solution will still be basic just by the presence of CO3(2-)? The confusion is this: ph only depends on [H+] then how come...

In Fig. 9-58a, a 3.50 g bullet is fired horizontally at two blocks at rest on a frictionless table. The bullet passes through block 1 (mass 1.20 kg) and embeds itself in block 2 (mass 1.80 kg). The blocks end up with speeds v1 = 0.630 m/s and v2 = 1.40 m/s (Fig. 9-58b). Neglecting the material...

As i understand it, the Maxwell equations in potential form (in the Lorenz gauge) are basically 4 independent wave equations for the 3 components of A and the 1 component of Phi, with J and ρ acting as source terms: Now from the usual formulation of the Maxwell equations and from experience...

I am a little confused about dimensions, if the nullspace of a matrix is spanned by the 0 vector, does that mean the dimension of the nullspace of this matrix is 0? In the problems I attached, both A and B reduced to the identity matrix. Note (2) is supposed to be dim(N(B)) and dim(col(B))...

Confused: What to do after Master's?? Hello Everyone. I am currently enrolled as a Master's student with bachelor's in mechanical engineering. I am now in my final year. But i have remained confused over what to do after my master's. I am confused between taking up a job, entrepreneurship(i am...

Confused regarding conservative and non conservative force... Ok , so here is my explanation : Suppose I take a box at a height 5m from a reference point upwards. Work done by gravity on the block is -mg(5) J. Upwards is taken as positive and downwards as negative. Then I again take that box...

Wavelength of a sinusoidal wave is defined as the spatial period of the wave, which can be measured between any two points on the wave where the shape repeats. But if my wave is defined as a function of time (like those of a simple harmonic oscillator), how can you say the distance along the...

Here is a question we did in class...Why in the answer do we take the derivatve? How do we know to take the derivative? What in the problem would have set us off to look for the derivative and set to 0? Consider an economy that is composed of identical individuals who live for two periods...

Eve deposited $8.000 in a 3-year certificate of deposit, which pays 2.2% compounded monthly. Find the account value at the end of the 3rd year and the amount of interest earned during the whole 3-year period. I think i use the payment to a sinking fund formula but i am not sure. possible...

Homework Statement I have a homework question: Calculate the effective address and determine the addressing mode that is specified for each memory operand in the following statements. (a) MOV EAX, [label1] ; label1 is at location 0x00D5A360 (b) MOV EAX, [EBX] ; EBX points to location...

Is it just so chemistry is extra confusing to students? I don't understand...

I am having trouble getting a set definition of what constitutes a manifold for example , I have the real plane R^2, and the sphere s = {(x,y,z)|(x,y,z)£R^2, x^2+y^2+z^2=1} Note £, is meant to be "element of". And I have a continuous function f mapping the real plane onto s such that...

I'm confused on how it would be impossible to be faster then light, is it your acceleration? or is it how fast you are going in comparison to some other frame of reference (I do see that phrase being thrown around here)? Because if 2 objects are moving towards each other at more than half the...

I`m not a physics expert and have loads of questions about electro magnetism, both classical and quantum. What is a field made of ? in classical it is essentially nothing but how does the force from the charge propagate through empty space. In quantum it says that its a cloud of virtual photons...

Homework Statement I'm trying to find the galois group of x^5 - 1 over Q, and then for each subgroup of the galois group identify which subfield is fixed. Homework Equations The Attempt at a Solution If w = exp(2*I*PI/5), then the roots not in Q are w, w^2, w^3, w^4. Its fairly...

I am confused about mixed quantum states, if the only observable states are pure eigenstates, since we have to measure to observe, what is the physical meaning of a mixed state?

How can a conducting sphere have no voltage at the surface, and yet have a surface charge when there's a charge outside of the sphere? Wouldn't the surface charge create voltage at the surface?

While I was studying I downloaded and printed a previous old test which already answered I tried to re-solve the questions by myself but there is one question made me confused as I get a result mentioned in the options but the marked answer is different. I am talking about question 3 in the...

Hi, I have just a few basic questions. I was in the army for about 6 years then worked as a CCNA for about 6 years before being layed off, entire company was farmed out to Philippians I believe. I am a disabled vet with a wife and 2 year old. I was accepted into the VA's chapter 31 program...

Hello, I am having issues understanding all the waves, there are a lot of equations involving sine and cosine..and then all the various ways frequencies are looked at. I'm talking about pendulums, oscillators, standing waves, and sound waves. They all look similar in there form, but it is a...

Find ∫from .6 to 0 x^2/ sqrt(9-25x^2) dx My teacher worked this on the board a little confused O obviously the trig sub is asintheta. But it isn't in the right form yet. So get it there you pull out a 25 --) sqrt(25(9/25) - x^2 ) 5sqrt((9/25)-x^2 so x= (3/5) sintheta so dx = 3/5costheta. so...

Homework Statement A 1.57 kg brick measures 20.0 cm x 8.00 cm x 5.50 cm. Taking the zero of potential energy when the brick lies on its broadest face. (a) What is the potential energy when the brick is standing on end? Note: You can treat the brick as though all its mass is concentrated at its...

A conditional statement is of the form A→B. Truth tables suggest that the converse, B→A ≠ A→B. It is also known that any two vectors A and B are perpendicular if and only if their dot products are zero. My confusion is... A dot B = 0 → A and B are perpendicular. The converse is...

Homework Statement 1. The question asks for the value of P(~A and ~B) - What equation to use? The Attempt at a Solution 1. I am confused though, is P(~A and ~B) same as 1 - P(A and B) or should I use, Pnot(A or B), and this is equivalent to 1 - P (A or B) ?Extra question... There is also...

1. The question states: "Two lights are placed along the x-axis at positions x1 = 3.00 m and x2 = 5.00 m. The lights flash at times t1 = 1.00 ns and t2 = 9.00 ns. An observer in a rest frame moving to the right sees the lights flash in the same location. Assume that the origins of the two rest...

Homework Statement At Earth's location, the intensity of sunlight is 1.5kW/m^2. if no energy escaped earth, by how much would Earth's mass increase in 1 day? Homework Equations ΔE=Δmc^2+ΔKE Rearth=6.378x10^3 The Attempt at a Solution I know that the change in kinetic energy does...

Homework Statement Homework Equations x^2 + y^2 = r^2 The Attempt at a Solution I understand everything, but the last segment. What vector B when added to vector A, gives a resultant vector with no x component and a negative y component 3.34 units in length? So 3.34 = Sqr Root [(0^2) +...

What is the action of acetylcholine and anticholinesterase. Confused! Hello everyone, Ok Acetylchlone is released from postganglionic parasympathetic fibres and preganglionic nerve fibres of both sympathetic and parasympathetic nerves. It also cause muscle contraction in neuromuscular...

So this is my first course in upper level physics, and I'm still trying to figure out special relativity. The problem: Two events occur at the same place in a certain inertial frame and are separated by a time interval of 4sec. What is the spatial separation between these two events in an...

you throw a ball straight up in the air with a speed of 7.25m/s. The moment the ball leaves your hand you start running away at a speed of 2.59m/s. How far are you from the ball the moment it hits the ground. So I've gotten better at these kinematics equations but this one has too many...

I thought Lorentz Transformations left Δt2-Δx2 invariant but, for example a frame moving at .5C for Δt =1 has Δx = .5 so Δt2-Δx2 = .75 If this is transformed by : to a rest frame Δt =0.65 has Δx = 0 and Δt2-Δx2≠ 0.75 not sure where I have gone wrong here, any help would be...

Well, I graduated in May with a degree in chemical engineering with minor in mathematics and CS from a small college in TN, (gpa 3.75) with 20k in debt . I have just received my green card 2 months ago. Previously I was on student visa, thus I could not allow to work off campus / also I could...

Could someone give me a short summary(if possible) of how discovering matter is made of vibrating energy will give explanation to all four fundamental forces?

So I'm a little confused about the nomenclature of this compound (CrO3). is it chromium (VI) oxide? chromic acid? and then Cr2O3 is just plain Chromium (III) oxide right?

Hello, I just downloaded the Java Development Kit (J2EE) and during the install I was asked to configure something called Glassfish. I don't understand what Glassfish is for. Is it only for Web development? What does it do for me?

Hey all, GR has just been explained to me in a lecture and I'm a little confused about a few things. I've been running through a few scenarios in my head and I don't see how they can occur without a paradox. One scenario is if you have two spaceships traveling parallel to each other at...

Breathing against a fan/pressure ... I'm confused... any help would be great Hi all, This post is in relation to breathing on a CPAP device which is commonly used to treat sleep apnea. What I am confused about is the effects of changing the pressure and the perceived affect on comfort of...