Zero Definition and 1000 Threads

Two isolated point charges -7μC and +2μC are at a fixed distance apart. At which point is is it possible for the electric field strength to be zero? I don't know where to start with only 2 numbers and no distances. I know that E= kQ/r^2

hi all, I was wondering if there is any industrial/common type of material (at around temperature of 3K) that can function as bolts/screws or thin sticks. This is to be used in a cryostat and ideally prevent any heat conduction from the material it is attached to during the process...

Homework Statement So on my first day of intro to quantum physics my teacher assigned a lot of calculus problems as homework. One of them problems was a quite lengthy proof that one integral is the equivalent of another, and I am so close to getting the correct answer! All I need to do to...

Homework Statement True or false If an object originally at rest is subjected to more than one non zero force but the forces sum to zero then the particle will not move. Homework Equations None The Attempt at a Solution I say false I think it something to do with angular...

The static friction force which provides the acceleration of a car does not move through a distance (the point of application is stationary with respect to the road at any instant). Isn't it that only external forces may change the translational kinetic energy of an object? If so, and if the...

Hi there, Can someone help out with this problem? Thank you.:redface: Homework Statement Consider two electric dipoles in empty space. The net charge of each dipole is zero, so does an electric force exist between them? Homework Equations F=kq1q2/r2 The Attempt at a Solution...

Hi everyone. This isn't a homework problem. Rather, I'm trying to understand how the δ term arises from the field of a dipole. Homework Statement Greiner supplies the following one-line derivation, which is easy to follow I guess, but doesn't make logical sense to me. Specifically, I don't...

We all know that there four fundamental forces in nature, viz. The gravitational force The electromagnetic force The strong nuclear force The weak nuclear force Now also we know that temperature of any system is the average kinetic energy possessed by the particles of the system Now...

Homework Statement Homework Equations See #1 The Attempt at a Solution Based on the information in the question, I did what I could, but in the back of the book they have an answer of -9.9a and I have no idea how? For the +3q on the right, I set the denominator to (2a+r)^2...

Suppose we consider a proton where we set the electric charge of the three quarks towards zero. At this point I assume we still would have the three quarks bound together? Now reduce the strength of the strong force by say ten times. I was told in posts that the radius of the proton depends on...

Is it possible to have a zero vector? The question arises in the context of conservation of momentum. In center of mass reference frame, the momentum of two masses involved in an elastic collision is zero before (as well as after) collision. It is because the two masses have equal and oppposite...

how can I prove that no current would flow in a wire connected between two wires of equal potential. For an example a resistor of 2 ohms carrying a current of 3 Amp and a resistor of 3 ohms carrying a current of 2 Amp, and a wire "A" is connected between them. Obviously, the potential difference...

What is the Lagrangian of interaction of photon and spin zero charge scalar?The vertex of photon and spin 1/2 charge fermion is proportional with e multiplied vertor gamma matrix,but I do not know what is the vertex of photon and charge scalar.I hear that a vertex is proportional with polynomial...

Homework Statement Given $$y''+e^{-x}y=0. \qquad (*)$$ Let ##y(x)## be any nontrivial solution of ##(*)##, show that y has finitely many positive zeros. Hint: Consider ##z''+\frac{C}{x^4}z=0## where ##C>0## is sufficiently large, which has a solution ##z(x)=x\sin \frac{\sqrt C}{x}##. Homework...

If you could create a small space on Earth in which a person could fit that was totally unaffected by gravity, or that was sheltered from the gravitational affects of external sources of gravity, what sort of affect on time dilation would be observed? Both for the person in the pocket, and for...

Homework Statement The question wasn't really written down. It was a question asked after an explanation, and it really wasn't straightforward. I'm going to try to make it into a intelligible thing. If there is a +3 charge and a -1 charge at a distance from one another, where to the right...

\displaystyle\int_0^\pi\dfrac{x dx}{a^2sin^2(x)+b^2cos^2(x)} I have to prove this to be equal to \dfrac{\pi^2}{2ab} but with my attempt at it this problem boils down to: \dfrac{\pi}{2ab}\bigg[\arctan\Big(\dfrac{atan(x)}{b}\Big)\bigg]_0^\pi which equals zero.

http://www.gocomics.com/berger-and-wyse#.UqXa09JDswA This puts a new spin on preparing some lunch. Although I wonder where the greens came from.

Homework Statement lim (sinθ-1/2)/(θ-∏/6) θ→∏/6 Homework Equations The Attempt at a Solution Direct substitution with ∏/6 gives 0/0 How do i get rid of the zero factor ?

Hello MHB. I am sorry that I haven't been able to take part in discussions lately because I have been really busy. I am having trouble with a question. In a past year paper of an exam I am preparing for it read: Let $f: (a,b)\to \mathbb R$ be a differentiable function with $f'(x)\neq 0$ for...

[SOLVED] Complex contour integral zero while containing a pole? Homework Statement ##f(z) = \frac{1}{z^2 +2z +5} = \frac{1}{(z-z_1)(z-z_2)}##, where ##z_1= -1+2i## and ##z_2 = -1-2i##. Now, let z be parametrized as ##z(\theta)=Re^{i \theta}##, where ##\theta## can have values in the...

If function is ##f(-x,-y)=f(x,y)##, is then ##\int^{a}_{-a}\int^{a}_{-a}f(x,y)dxdy=0##? Thanks for answer.

Hello MHB, I Was woundering WHY is zero in plural? Exemple "I got zero cats". What do you think? Regards, $$|\pi\rangle$$

I have two questions: [SIZE="5"](1)As the tittle, if u(a,\theta,t)=0, is \frac{\partial{u}}{\partial {t}}=\frac{\partial^2{u}}{\partial {r}^2}+\frac{1}{r}\frac{\partial{u}}{\partial {r}}+\frac{1}{r^2}\frac{\partial^2{u}}{\partial {\theta}^2} and \frac{\partial^2{u}}{\partial...

Hi, I'm trying to figure out something I'm pretty sure is true, but don't know how to prove it. I couldn't find the answer with a google search, but hopefully someone here knows the answer! So I have a linear least squares multiple regression model: Y=a+bX1+cX2+e where a is the intercept, X1...

what is the physical meaning of first pressure derivative of bulk modulus at zero pressure. if it is ∂k/∂p, i say how it change with pressure, if it is at zero pressure?

In the context of my work (linear differential equations), it can not be zero. But why?

Ok, I have to do my case study on zero gravity but I am just not understanding it. It says weightlessness is similar to when you are in a free fall, for example in an elevator because you are accelerating at gravity's force? I don't get what EXACTLY makes us weightless just because we are free...

Is there any data about such measurements? I think, there has to be a pressure gradient in a floating liquid sphere due to surface tension.

can u give me the method to find the factorial of zero ?

Homework Statement How do I prove that Rn(x) is zero as n approaches infinity for the nth taylor polynomial of 1/(1-x) when x is between -1<x<1 Homework Equations 1/(1-x) Rn(x)=M*(x-a)^(n+1)/(n+1)! nth derivative of 1/(1-x) is n!/(1-x)^n+1 The Attempt at a Solution the nth...

Hi, I have a question to ask. On my notes that my teacher gave me, he said that there are some errors in the notes. He had not responded to me which are the errors yet but he said about zero errors in vernier calipers and micrometer screw gauge. The question is: On my notes, it says that...

Homework Statement Could you guys please verify this proof of mine? I want to show that a limit with particular property does not go to 0. It is part of the proof that when a sequence have an ever increasing term then the limit of the sequence is not 0. The Attempt at a Solution The...

Homework Statement An object is moving along some path. the total work done on the object during this process is zero. Homework Equations no equation The Attempt at a Solution A the speed of an object has decreased. B the speed of the object may have changed. C the object must be...

Hello! First of all, thank you for your time in reading my post. Secondly, I am not looking for people to freely give me the answers. With all that said... Homework Statement I have a test point randomly selected on a graph, but what I am trying to figure out is where on this graph...

In a matrix the sum of element of a matrix in a row times it's co factor of that elemt gives the determinant value, but why does the sum of element of a matrix times cofactor of different row is always zero?

Let A be a Hermitian operator with n eigenkets: A|u_i\rangle = a_i |u_i\rangle for i=1,2,...,n. Suppose B is an operator that commutes with A. How could I show that \langle u_i | B | u_j \rangle = 0 \qquad (a_i \neq a_j)? I have tried the following but not sure how to proceed: AB -...

how vector area of a closed surface is zero?

I am having issues with multiple gauss' law problems. Assume we have a charged spherical surface. Inside the surface, E=0V/m. But why? I understand that at the center it should be zero due to symmetry, but why would it be zero at some point say, inside the surface but not at the center...

I'm currently reading John Taylor's Classical Mechanics. Near the end of Chapter 3, he states "Because the table is mounted on a frictionless axle, there is no torque in the z direction. Therefore, the z component of the external torque on the system is zero and the [system's angular momentum in...

If a resistor of a resistance = 6 ohms is connected to 2 wires of zero resistance (0 ohms) in a DC circuit with a battery of voltage = 12V, the current throughout is 2A. The voltage drop across a 0 ohm wire is V = R*I. Because R = 0, the voltage drop across the wire is 0V. The only way for this...

I have always read that a wormhole will quickly collapse in on itself due to its own gravity, forming a black hole, unless it is held open by some exotic matter that has a negative energy density. But couldn't there exist a wormhole with zero spacetime curvature? It would therefore have no...

Homework Statement ne of the methods used to train astronauts for the effects of "zero gravity" in space is to put them in a specially equipped plane which has been stripped of seats and fitted with padded walls. The pilot then takes the plane up to an altitude of typically 9300 meters and...

Homework Statement How do I show that this integral tends to zero as b tends to a ? Homework Equations \int_a^b \int_0^a (f(a)-f(y))(x-y)dy(b-x)dx The Attempt at a Solution I'm not sure how to start. Any hints or ideas will be very much appreciated. We are given that function...

Hello, When given a truss structure, how does one tell visually just by looking at the structure which members are zero force members?

Homework Statement A one-dimensional harmonic oscillator is in the ground state. At t=0, the spring is cut. Find the wave-function with respect to space and time (ψ(x,t)). Note: At t=0 the spring constant (k) is reduced to zero. So, my question is mostly conceptual. Since the spring...

Hello i would like to know why this integral is Zero: $$\int_{\gamma(0;1)}\frac{1}{z+2} \mathrm{d}z$$ Well i know by a fundamental result that: $$\int_{\gamma(a;r)}\frac{1}{z-a} \mathrm{d}z=2\pi\imath$$ But here the point $$z=-2$$ lies outside $$\gamma(0;1)$$ so what is the reasoning behind...

in physics II, i learned about how the electric potential goes to zero as r goes to infinity. Okay, well, this was when we were dealing with two positive charges. ie a repulsive force. now I'm learning about gravitational potential now and i see this in my notes: \Phi\rightarrow0, r\rightarrow∞...

Well, I know this have no sense. But I was trying to solve a problem on Cohen Tannoudji. The problem is in chapter IV, complement ##J_{IV}##, exercise 8. It says: Consider an electron of a linear triatomic molecule formed by three equidistant atoms. We use ##\left | {\phi_A} \right >, \left |...

Homework Statement i'm having a bit of trouble understanding/visualising why the electric potential is zero in the red cross within region III and the green dot within region II from my current understanding, the green dot is where the potentials from both charges are equal and...