Zero Definition and 1000 Threads

Okay, this is a question that's always kind of bothered me. According to dozens of articles and interviews with NASA employees or professional astronomers, one of the biggest dangers of long term space travel is the bone and muscle loss. That totally makes sense; being in zero G is even worse...

Hello Experts, I am a physics newbie with big ideas. I have a question. I am thinking about how to produce a zero Resistance Current. We know we can do this using super-conductors in sub zero temperature, but maybe there's another way. My assumptions (which could be wrong): 1) Resistance in a...

Homework Statement I'm a new one on general relativity there are two prolems: first how to certify the proper length of light is zero second ,how to certify proper length of light ,do not change in all inertial frame Homework Equations for second question, probally Lorentz transform, The...

I recently read about zero sequence braking of induction motor. In zero sequence braking of induction motor, the stator phases are connected in series and a single phase ac supply is connected across the series combination. Thus, the currents in all three phases are co-phasal, which are called...

Homework Statement A -10.0 nC point charge and a +20.0 nC point charge are 15.0 cm apart on the x-axis. What is the electric potential at the point on the x-axis where the electric field is zero? Homework Equations ##E = k\frac{Q}{r^2}## ##V = k\frac{Q}{r}## The Attempt at a Solution I've set...

When we say a fundamental particle is 0 dimensional, is that literal or figurative? Is it physically possible that a particle has it's properties (like charge, mass) spread out in a finite volume, but can be "shrunk" to increasingly small volumes when we measure it?

To measure negative sequence impedance of an alternator, we short the white and blue phases, measure the current and then divide it by the voltage of the red phase. Then to measure zero sequence impedance, we short the rotor and connect the stator in open delta and inject a current. My...

How does the zero time delay between illumination of light and emission of photo electron provides an evidence for the particle nature of light?

I've come across many instances where sometimes the error tends to zero but other times it does not. Let me give you a few examples. 1. When I calculate the volunme of a sphere summing up discs of height dy from -R to +R, the error in volume tends to zero as Delta y->0 but when I'm calculating...

Homework Statement Two pairs of charges are shown in Figure 1. Homework EquationsThe Attempt at a Solution I originally thought that the electric field past point 7 (i.e. points 8,9, 10) was the solution. However, this is wrong. I then considered point 1, yet that was wrong too. I even...

Hello forum members, The electric potential for a point charge is a scalar function given by $$V = \frac {kq}{r}$$ This means that the potential has a nonzero value everywhere. The potential becomes ##V=0## when ##r=\infty##. However we know that what matters is the potential difference...

What is infinity times zero? Isn't it zero? I mean, infinity times zero is the same as zero an infinite amount of times, and adding zero infinitely would give zero because even though zero is always being added, this process is the same as nothing ever being added to zero.

A current carrying conductor produces a magnetic field but what if there is an object which has the same speed as current. Will there be magnetic field by the current carrying conductor for that object?

Today when I ask a professor about maxwell eqation He tells me " it seems that the unknowns exceed the number of equations. What are the missing ingredients? The answer is the boundary condition .With appropriate boundary conditions, zero divergence and zero curl will nail down a unique solution...

Homework Statement Hi, Please see attached. I am trying to show the second equality , expressing all as a total derivative (I can then show that ##\delta S = ##) Homework Equations See above The Attempt at a Solution So the ## m ## term is pretty obvious, simply using the chain rule. It...

Homework Statement Given the polynomial function ##x^4+x^3+2x^2+4=0## solve it if you know that it has at least one complex zero whose real part equals the complex part. Homework Equations 3. The Attempt at a Solution [/B] My guess is that if this function has one complex zero it must have a...

Why do all the volume temperature curves of an ideal gas intersect at the same point on the temperature axis ?

I'm currently working through the book Algebra by I.M. Gelfand and A. Shen on my own. (As advised here: https://www.physicsforums.com/insights/self-study-basic-high-school-mathematics/#toggle-id-1) This isn't really homework so I wasn't quite sure where to post this. Anyway, I've got a question...

In one of my problems, I have this set of data. I have to create two best fit lines, and find a value of absolute zero for both. The first best fit line is to be made assuming there is NO uncertainty in P. This is rather straightforward, just use the normal linear regression, find a slope...

Hey! :o I want to show that for $A,B\in \mathbb{R}^{2\times 2}$ the $U=\{X\in \mathbb{R}^{2\times 2}\mid AX=XB\}$ is a vector subspace of $\mathbb{R}^{2\times 2}$. We have that it is non-empty, since the zero matrix belongs to $U$ : $AO=O=OB$. Let $X_1, X_2\in U$ then $AX_1=X_1B$ and...

is enthalpy change during isothermal process zero? if it is zero then what is the significance of enthalpies like enthalpy of vapourization or fussion since during phase transformation temperature remains constant.

Hello! (Wave) We consider the following Cauchy problem $u_t=u_{xx} \text{ in } (0,T) \times \mathbb{R} \\ u(0,x)=\phi(x) \text{ where } \phi(x)=-\phi(-x), x \in \mathbb{R} $ I want to show that $ u(t,0)=0, \forall t \geq 0 $. We have the following theorem: Let $\phi \in...

Pressure can exist in a container of gas even if there is no gravity. From kinetic theory of gases it is assumed that pressure exists due to momentum transfer between molecules and the wall. Suppose I have a closed container on Earth at sea level filled with air. Now I carried it to zero gravity...

Hello guys, I am confused about when we can multiply and divide by the variable. I know the if zero is hidden as a factor then we can not divide or multiply. eg. x/2x+1=0 are we allowed to divide both side 2x+1. Although zero is hidden value of x, there are no other ways to solve this...

Hello! (Wave)Suppose that $B_{\epsilon}=\{ |x- \xi|< \epsilon\}$ and $E(|x- \xi|)=\left\{\begin{matrix} \frac{1}{(2-n)w_n}|x-\xi|^{2-n} &, n \geq 3 \\ \\ \frac{1}{2 \pi} \ln{|x-\xi|} &, n=2 \end{matrix}\right.$ So when $ |x- \xi|=\epsilon $ then $$E(|x- \xi|)=\left\{\begin{matrix}...

If i have two sinusoidal ac signals of 220V with the different phase angle i.e. there is some phase difference between them. Then can i make the phase difference zero?? Please tell

Hello! (Wave) Let $u(x) \geq 0$ be harmonic in $\Omega$ and $u|_{\partial{\Omega'}}=0$ where the space $\Omega'$ is a proper subset of $\Omega$. I want to prove that $u(x) \equiv 0$ in $\Omega$. If we suppose that $u \in C^0(\overline{\Omega'})$ we can deduce that $u(x)=0$ in $\Omega'$. In...

I've lately began working with Newtons laws problems at school again, and I've already ran into a few problems. When making calculations and solving problems, it is often nessecary to understand when forces are equal to zero, and when they are not. Since every force has an equal and opposite...

Hey, I have some questions regarding zero sequence current flow in a multi phase system I was hoping some kind soul could help me with. Imagine the following scenario illustrated in my bad paint drawing below: A delta-wye(n) transformer are supplying a non linear load producing 3rd harmonics...

Suppose I have the following integral: \int_{2}^{∞} \frac{1}{x^2-x}dx Before substituting the boundaries I get ln|x-1| - ln|x|. When I put the boundaries in I get ∞ - ∞ - 0 + ln(2) = ln(2). But how do I know those infinities cancel? Is it because both are infinities of real numbers and...

I am working on this problem which has been baffling me since the beginning: Prove that $A^k = 0$ and $A^{k-1} \neq 0$ if $A_{k \times k}$ is a zero matrix but with entries of 1's right above its diagonal. For example, if $k = 3$ the it will look like this $$\begin{pmatrix} 0 &1 &0\\ 0 &0 &1\\...

Homework Statement Let V denote the set of ordered pairs of real numbers. If (x, y) and (w, z) are elements of V and a is a real scalar, define (x, y) + (w, z) = (x + w, yz) and a(x, y) = (ax, y). Is V a vector space? Homework EquationsThe Attempt at a Solution Going through the vector space...

I know there is a lot of answers out there, but so far none really answered my question. Say I have this radioactive conductor sphere that has a negative charge. Of course, all the negative charges will be spread evenly on the surface and there SHOULD be 0 electric field inside the conductor...

I was reading about the definition of electric field. It said that electric field at a point due to a source charge is the force exerted by it on another charge placed at that point divided by the magnitude of charge placed at that point. But, obviously, if we place any finite charge in electric...

Hi. I learned that in an ideal conductor in a circuit, the voltage drop is zero. But how does this agree with the basic definition of voltage $$U_{AB}=\int_A^B \vec{E}\cdot d\vec{s}\enspace ?$$ The electric field inside a conductor only vanishes in static conditions, but in an electric circuit...

Is it possible to magnify an object if the magnifier is sitting directly on top of the object (a focal length of zero)? How can this be accomplished if it is not possible with a traditional magnifier?

Hi Guys, Thanks for looking at the post firstly. I'm in the process of creating a chamber roughly around 30mm x 50mm x 70mm (W, L, H). The chamber will be used below the typical refrigeration temperature (-18°) of around -50°C. Please could you offer some advice where to start with this. 1...

Hello,I had a discussion with my professor. He tried to convince me but I couldn't understand the idea. The Stokes Theorem (Curl Theorem) is the following: My professor says that the value of the equation should be zero whenever the area of integration is closed! (which will make a volume in...

Homework Statement A long wire (X) carrying a current of 30 A is placed parallel to, and 3.0 cm away from, a similar wire (Y) carrying a current of 6.0 A. What is the flux density midway between the wires: (a) when the currents are in the same direction, (b) when they are in opposite...

In QM, we all know that the wavefunction ψ is zero when x is infinite. However, Is dψ/dx also zero when x is infinite? And the d2ψ/dx2?

Homework Statement A source of sound frequency 550 Hz emits waves of wavelength 600 mm in air at 20 °C. What is the velocity of sound in air at this temperature? What would be the wavelength of the sound from this source in air at 0 °C? Answers: 330 m s-1, 579 mm 2. The attempt at a solution...

Homework Statement Particle 1 of charge +4.0 μC and particle 2 of charge +1.0 μC are held at separation L=10.0 cm on an x axis. Particle 3 of unknown charge q3 is to be located such that the net electrostatic force on it from particles 1 and 2 is zero. In the included figure, particle 1 is...

me and my friend were talking on facebook and we couldn't think of an answer to the question, would water pressure decrease in zero G, you can see how far along we got before getting stuck in the picture belowhttps://www.physicsforums.com/attachments/105576

Is there some geometry in which a coordinate transformation of a vector of magnitude zero transforms to a vector that does not have a zero magnitude? Since the formula for the magnitude of a vector is √(x12+x22+...xn2), I can see no way for it to have magnitude zero unless every component is...

Hello everyone, I have the this inquiry: if I compute de following integral: http://micurso.orgfree.com/Picture1.jpg by numerical methods I get cero as a result. I used Maxima and Mathematica and their functions for numerical integration give me an answer equal to cero. But, if I apply...

Homework Statement [/B] Consider an isotropic, homogenous dielectric sphere of radius R and constant relative permittivity ε, also permeated by a uniform free charge density ρ. Give an expression for the electrostatic potential V at the centre of the sphere by line integration of the electric...

The common explanation is this: If the conductor has a net charge, then the charges repel each other until they arrange themselves symmetrically around the outside of the sphere, and if you do the math the electric field will cancel out everywhere inside the conducting sphere. Alright, but what...

Okay - a classic trap . multiplication times zero . I have a 3 foot bar weighing 10 lbs . its attached along its mid point to an axle . how much torque / force - do I need along its axle ( motorized ) to get it to spin 30 rpm or 60 rpm ? its in equilibrium , but of course it needs FORCE...

Hi everyone, Thank you in advance for taking the time to read my question and for your help. I really appreciate it. The question is set out as follows: Given the set 𝑆 = {𝑎 sin (𝑥+𝑏) | 𝑎, 𝑏 E R}. The addition of elements 𝒔1, 𝒔2 ∈ 𝑆 is defined as follows: 𝒔1 +𝒔2 =𝑎1 sin (𝑥+𝑏1)+𝑎2 sin...

Homework Statement Resultant of which of a following may be equal to zero? 1)10 N, 10 N , 10N 2) 10 N, 10 N , 25 N 3) 10 N, 10 N , 35N 4)None of these More than one option can be correct. Homework Equations Addition of vectors The Attempt at a Solution 1) Resultant of these three forces can...