Confusion Definition and 1000 Threads

Homework Statement I currently reading about transistors in a solid state course. And the transistor is a MOFSET, which I have to describe. I can't really find a nice figure of the one I have in my book, so I will just try to explain my confusion. It says that you make a MOFSET by having a...

Hello, I've read through several sources about the EPR Paradox but I'm not sure I'm understanding everything. I know that: -the paradox in question seems to be due to a violation of the principle of locality -there is no useful transferred faster than c regardless of which axes the two...

Hello, What "choice" does the Axiom of Choice permit us to make? I've searched high and low and not found a satisfactory answer. To me it seems to add no new information to its hypotheses: Given an arbitrary collection of non-empty sets, isn't it true, without assuming anything and just by...

When students are first introduced to special relativity, the first thing they are taught is the derivation of the gamma factor and time-dilation, and it goes something like this: Suppose there are 2 observers in space, let's call them Alice and Bob. Let's assume Alice is stationary from our...

Hi, please could someone kindly answer a few questions regarding the higgs boson. Everywhere I read about this topic I seem constantly faced with information that is not consistent. I have focused on sources (mainly YouTube videos) of well known physicists and other Physics Forum threads in an...

Greetings, I am a bit confused on an aspect of contour integrals. Wikipedia gives the following example of an integral where the residue theorem can be used (it also finds the integral in a couple of other ways, but I am mainly interested in doing it using residues): We want to calculate...

Why does the size of an obstacle have to be comparable to the wavelength of radiation for diffraction effects to be noticable ? Secondly, if the size of an opening is much smaller than the wavelength of the radiation , how does the radiation interact with the opening ? Third, can the same things...

Projectile motion consist of horizontal and vertical motion. The horizontal motion consists only of constant velocity, that is, the velocity of the object The vertical motion consists only of constant acceleration, that is, acceleration due to gravity. Yet... we have vx = vcos and vy =...

I'm really confused about blood transfusion, I know that O group is a universal Donner but how since it has both antibodies A,B, why doesn't agglutination happen? For an example o group is donated to an individual with A blood group why doesn't the antibody A of O group cause Agglutination in...

Q1) What angular velocity would be required for your effective weight at the equator to be third of that the north pole? You may neglect all inertial forces except the centrifugal. I understnad the majority of my books solution which is that: At the equator, the centrifugal force is...

I should start by saying that I am a bit embarissed by asking such a silly question By simply equating the mass-energy formula with the temperature dependence of heat... M*c2 = M* cm *ΔT it strikes me as odd that the mass cancels, c2 = cm *ΔT I was doing this in order to calculate...

Hey all, Perhaps this is a bit stupid... I'm familiar with the normal procedure of calculating rotational inertia (using integration, parallel axis theorem, etc.). However, I had a confusing thought: if the center of mass of a body is the point at which you can treat as all of the mass being...

Not homework just my own revision. If sin a = –cos b = 3/5 and a and b are both in the second quadrant, what is cos (a – b)? Now keep getting the answer 0, but the answer is apparently 24/25, now they use the trig subtraction formula, I just did cos ((arcsin(3/5) - arccos(-3/5)) I got 0 as...

Hi everyone, If I have a static cylinder on an inclined rough plane at an angle alpha supported by a chord under tension, which leaves the surface of the cylinder at a tangent upwards and parallel to the plane. Does the weight component trying to pull it downwards equal the sum of the friction...

Hi, I stumbled upon this while working on a problem on my physics homework. I still want to solve the problem myself if possible though so I won't post it here, instead, I'll post what is confusing me. Consider orbital motion with potential U(r), where U(r) is any arbitrary function of r. I...

I have a confusion: If we push an object of 10 kg with force of 60N once, does it accelerate constantly with 6m/s/s forever neglecting any resistance ? So, does this mean if this moving object collides with something the maximum force it applies is 60N?

Hi guys I always get confused when I do the right hand rule like here when I apply it to this problem I am getting different answer than what the book have. A uniform magnetic field B, with magnitude 1.2 mT, points vertically upward throughout the volume of the room in which you are sitting...

Sorry I can't get latex working so bear with me as I am new to it. I start A-level physics in a week and during my own research I have come across something that confuses me. Acceleration= Final velocity - Initial velocity divided by time. What is confusing me is when your deriving other...

Homework Statement I have to calculate the Ksp value for calcium hydroxide from experimental data. We titrated 10.00 mL of saturated Ca(OH)2 aqueous solution with 11.00 mL of 0.01607 M EDTA. Homework Equations The Ksp formula is given in my manual as [Ca^2+]*[OH^-]^2 The Attempt at...

Here's the question: The PCB concentration of a fis hcaught in Lake Michigan was measured by a technique that is known to result in an error of measurement that is normally distributed with a standard deviation of .08 ppm. Suppose the results of 10 independent measurements of this fish are...

Hello, This is my first post here. I am sorry if this is the wrong place for this question or if my phrasing is unclear. -x^n≠(-x)^n -x^n=-(x^2) I am slightly confused by this because at the level I am at right now (i.e. pre-calculus) and before, I have seen statements that contradict...

i solved a problem in all SI units and got certain value of angular acceleration. What is the unit of the value? Is it in radian/s^2 or what?

[SOLVED] Inverse signs on both sides of an equation [Confusion] Hey everyone, I've just reinserted myself in maths after so many years, done a lot of review but I sometimes fall on small "glitches" between my test answers and the suggested answers in my textbook. I've been getting confused...

Hi, I've managed to get myself confused over the simplest thing. Intuitively I'd think that gravitational potential energy is proportional to distance as described by the near-body equation GPE=-mgh. The alternative for farther bodies (-G*M*m/R) has me confused because it is inversely...

Homework Statement Small blocks, each with mass m, are clamped at the ends and at the center of a rod of length L and negligible mass Compute the moment of inertia of the system about an axis perpendicular to the rod and passing through a point one-fourth of the length from one end...

Greetings, If we have a function y=f(x), we can calculate the surface area traced by that function when rotating about the x-axis as 1: S=∫dx\,2πf(x), which makes perfect sense to me. I am told that, if we have x=x(t) and y=y(t), the equivalent expression is 2...

1.) an inner product of a state vector represent by <\psi|\psi>. sometimes the notation is like <\phi|\psi> is mean transfer from state |\psi> to <\phi|.it mean the former 1 do not transfer the state? what is the difference between both? 2.) what is mean by <x|\psi>? is it mean x(position)...

Hey, everyone. I am going to post a question—but it's not the question I need help with. It's something deeper (and way more troubling). Consider a particle of mass m subject to an isotropic two-dimensional harmonic central force F= −k\vec{r}, where k is a positive constant. At t=0, we...

Hi, please could someone guide me to a correct definition of voltage. I have looked through previous posts and there seems to be conflicting definitions. My school book and some posts on the forum say voltage "pushes" the current. However, I can't see how this could possibly be true for the...

Hi In the waveform picture i attached, I don't know why the square wave is floating instead of being on the 0 of the x axis. I also attached schematic of the pwm circuit. By the way, this is a pulse width modulator circuit made of 4 op amps, U2D is a schmitt trigger to generate sqaure...

I am trying to conceptually understand this relationship. One thing that's not helping is I keep hearing the phrase "the resting length" of muscle. It's using the word "THE" as if there is one resting length. This phrase implies that the length stays the same no matter how bent my elbow is at...

I'm reading about planning algorithms and I'm having some difficulty understanding a bit of notation here. The pdf I'm reading is "planning.cs.uiuc.edu/ch2.pdf" and the equation in question is on page 11. I'm not sure I understand what the min operator with all the subscripts actually means...

Hi friends, I have Kinetic energy problem during collision. Please Help me in solving this. Thank you all in advance. The problem is as: https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-frc1/q71/s720x720/1380301_1432382870322152_49372184_n.jpg Attempt...

Homework Statement How many times do we need to roll a fair die to get a better than evens chance of at least one six? The attempt at a solution Let n be the number of rolls. Am I trying to find how large n must be so P(At least one six)≥ 1/2? I'm working on the basis that I need to solve...

Hi, From the basics of 3 phase power, I believed that if you had a delta source which had Line Voltages and Phase Voltages of 100V, if you converted this into a star source, the Equivalent Star Line voltage would still be 100V and the equivalent star phase voltage would then be 100V/sqrt(3)...

Homework Statement Determine the output level (maximum positive or maximum negative) for each comparator in Figure 4-52. Homework Equations A_{ol}=\frac{V_{out}}{V_{in}} The Attempt at a Solution I am new to comparators but I thought that since all of these op-amps are...

I read that nuclear binding energy is the energy required to separate a nucleus into its comprising nucleons. Why then is mass defect calculated from this? How is the nuclear binding energy graph used to calculate energy released from fusion? Please explain in layman's terms, if you could...

For incompressible substances you have a change in internal energy represented by ΔU = mcΔT where T is temperature. I've also seen ΔH = mcΔT and ΔQ = mcΔT where H and Q are enthalpy and heat, respectfully. Does that mean that all of these are the same? I heard H becomes U...

Apologies for the long post this is going to be, but at the moment I am doing A-level chemistry and physics, and I am learning about electron orbitals and quantum physics at the same time, so I have reached a state of confusion. (At a higher level than that required for the A-level; I'm not...

Homework Statement http://imageshack.us/a/img812/8836/5tfn.jpg Uploaded with ImageShack.us Find F such that the moment around A will not exceed 1000N*m for any value of θ. Homework Equations M = fdThe Attempt at a Solution I got the right answer, I found the distance of a -> b AB= √( (2^2)...

A car travels in a straight line for 5.3 h at a constant speed of 60 km/h. What is its acceleration? Answer in units of m/s2 So far, to my understanding so far acceleration is change in velocity over time. So 60 over 5.3, which is 11.32 km/h2 Then I converted to m first, which is 1132...

Hi all, Something has been troubling me. To begin with, I have never been certain about this concept of 'extrinsic' thermodynamic variables. I mean, they don't have to be linear with system size, right? They just need to increase with system size? And also, I have a specific 'example problem'...

Homework Statement I am trying to understand why, in an example in Griffiths E&M (3rd ed, 8.1) says that the Poynting vector of a current carrying wire that is being heated via resistance (Joule heating), has a Poynting vector pointing radially inward. The E field is parallel to the wire, B...

According to wikipedia a total order ≤ on a set X is one such that If a ≤ b and b ≤ a then a = b (antisymmetry); If a ≤ b and b ≤ c then a ≤ c (transitivity); a ≤ b or b ≤ a (totality). I'm wondering why antisymmetry is a condition since, as far as I can see, totality discounts...

Suppose we have a wedge with angle θ on which there is a block. We are pushing the wedge with the least force required to keep the block stationary. If the acceleration of wedge is A then the acceleration of the block along the inclined plane will be gsinθ+Acosθ=0. That means A is negative. How...

The solutions say transitions B and C are allowed. Does anyone know why we can neglect the rule about delta(m_j)=-1,0+1? I don't see any way to deduce the value of m_j values. Also if anyone could clarify what is meant by the small "l" and big "L" rules for the electric dipole that would be...

Hi, I'm getting a bit confused about the adjoint representation. I learned about Lie algrebras using the book by Howard Georgi (i.e. it is very "physics-like" and we did not distinguish between the abstract approach to group theory and the matrix approach to group theory). He defines the...

I have been trying to understand pascal's barrel experiment in a more qualitative sense but I can't get my head around it at all. Pascal supposedly had a strong wooden barrel which he attached onto it a very thin pipe which was 20m tall. He then poured water into the top of the pipe until both...

Hey everyone, I'm a bit confused about how exactly the transformer works. What I have gathered from wikipedia is that basically what is happening is a low voltage DC is pulsed through the primary winding via a transistor, causing current build-up. When the pulse is through, the current in the...

Homework Statement From Young and Freedman's University Physics, 9th Ed., Problem 4-49. Two blocks are connected by a heavy uniform rope with a mass of ##4.00## kg. An upward force of ##200## N is applied to the top block, which has a mass of ##6.00## kg. The lower block has a mass of ##5.00##...