Point Definition and 1000 Threads

What if there is a universe with just one point charge in existence....just a charge with vast emptiness around it....now here all laws of physics remain same... But is the concept of field and energy defined there??

Homework Statement A uniform rod (mass = 5.0 kg, length = 0.3 m; the rotational inertia of the rod relative to the axis through its centre of mass is I = (1/12) ML^2 ) is free to rotate about a frictionless pivot at one end. The rod is released from rest in the horizontal position. What is the...

Is there a programmable telescope that will point to any spot on Earth from my location that I could simply plug in the latitude and longitude and it would point at the location anywhere on Earth. For instance, if I wanted it to point at the LHC (Large Hadron Collider), could I just plug in the...

Homework Statement Homework EquationsThe Attempt at a Solution Option (a), because the potential is 0 on the surface, and potential due to point charge is positive so there must be negative charge on the surface. Since opposite charges attract each other, there is an attractive force...

Homework Statement A current at point A of 2A flows through a resistor (3 ohms), a battery of 20V (negative terminal first), another resistor (1 ohm) and a battery of 6V (positive terminal first). What is the potential difference between A and B Homework EquationsThe Attempt at a Solution I...

Homework Statement A uniform rod (length = 2.4 m) of negligible mass has a 1.0-kg point mass attached to one end and a 2.0-kg point mass attached to the other end. The rod is mounted to rotate freely about a horizontal axis that is perpendicular to the rod and that passes through a point 1.0...

I shall try to expose my question as briefly and clearly as possible. Within a very old and classical approach (Newton), discussions take place in a three-dimensional Euclidean space and the concept of force is represented by a vector which is proportional to the mass of the object at hand (m...

Point Particle in Relativity and Electrodynamics: “The Classical Theory of Fields” – by Landau and Lifshitz, in its discussion about classical size of a particle, concludes that:- Thus we come to the conclusion that in classical (non-quantum) ‘relativistic mechanics’, we cannot ascribe finite...

So I made this diagram of the order imposed on the set of topologies on a 3 point set. Each small circle is a topology with the circle elements being the open sets. The larger circles join isomorphic topologies together. The ordering was messy when I tried to draw inclusion from each topology to...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] The thing to remember is that inside the Earth surface, the gravitational field does not remain inversely proportional to ##r^2##. The equation of motion is ## \ddot r = \frac { -gr} R## ....(1) This means that the...

Something's been bothering me about the PhD application process. I know that your future advisor is the most important aspect in choosing a graduate school, and that future success with obtaining postdocs, etc. will depend primarily on your research prowess (which is heavily dependent on if you...

Homework Statement A point charge q is located a distance d meters from an infinite plane. Determine the electric flux through the plane due to the point charge. [/B] Homework EquationsThe Attempt at a Solution I consider another infinite plane at a distance d in the opposite direction. Now I...

Homework Statement Homework EquationsThe Attempt at a Solution I will try to choose the correct option using the common sense instead of solving it. As d decreases, the flux should increase. For R>>d, only option (a) and (d) satisfy this condition. Now, for choosing between (a) and (d)...

Hi, is there an alternative form of the zero point energy for free electrons, where there is no space interval L to be quantized in? The zero point energy for electrons in an atom can be simplified to a variant where Z^2 is present in the nominator, however, these are not free electrons. Can a...

This may belong to the computing subforum, let me know if this is more true than having it here in the math forum :) My questions are 1) Suppose there is a plane in 3D space and I have 3 points to define it: p1 = {x1, y1, z1} p2 = {x2, y2, z2} p3 = {x3, y3, z3} and I want to put a particular...

From the basic definition of vacuum energy as being tied in with the Uncertainty principle, I would expect this not to include the Cosmic Background Radiation. Right? On the other hand, in figuring out (a) the Casimir effect, one attributes the force to the field between the plates carrying...

Homework Statement A person with a near point of 100 cm , but excellent distant vision, normally wears corrective glasses. But he loses them while traveling. Fortunately, he has his old pair as a spare. If the lenses of the old pair have a power of +2.55 diopters , what is his near point...

I know that Q value of a reaction is the difference between total initial mass-energy and total final mass-energy of all the products. Then shouldn't be this also the maximum kinetic energy and hence endpoint energy of an electron in beta decay. But what I have read endpoint energy ##E_0 = Q +...

Hey, Theory: The voltage of a thundercloud is too low to ionize air particles and to produce a thunder. Particles of cosmic radiation are the trigger. I calculated whether the voltage of a thundercloud is enough to ionize air particles but the voltage was always to low. So I wanted to know...

$\text{Determine the smallest distance between point}$ $$P(1,1,1)$$ $\textsf{ and the line $L$ through the origin $L$ has the direction}$ $$\langle -4,-5,8 \rangle$$ ok just barely had time to post this but was ?? about direction presume going off of this $\textit{Distance between point...

Homework Statement Show that ##x^2y''+sin(x)y'-y = 0## has a regular singular point at ##x=0##, determine the indicial equation and it's roots. Homework Equations For a DE in the form of ##y''+p(x)y'+q(x)y=0##, if both ##p(x)## and ##q(x)## are not analytic at ##x=x_0##, and both...

I don't understand the difference between the elastic limit and the yield point. I understand that if you stretch a material within the elastic limit, then the material should return to its normal shape. However, the yield point is described as the point at which a permanent increase in length...

Homework Statement I have a system of coupled differential equations representing chemical reactions and given certain initial conditions for the equations I can observe oscillation behaviour when I solved the equations numerically using Euler's Method. However, then it asks to investigate the...

Homework Statement Why is that we can set two variables zero in an equation of a plane to find a point on that plane? What is the proof for this? Homework EquationsThe Attempt at a Solution

Hi The first thing to say about this is that I don’t have a clue where to start. What I’m looking for is somewhere (maybe a website or just a brief introduction) I can study – and learn – about the forces involved and the maths required. _______ Say I have an item/length/beam/weight/etc (C...

Hey! I just came across this text ; from http://www.feynmanlectures.caltech.edu/II_40.html I tried to find "the law of hydrostatics" on the internet, to find no other mention of it. (would appreciate links to more details on it or any ideas regarding the topic) What is really puzzling is how...

Homework Statement https://imgur.com/gallery/vCOZq Its question 26, and the figure can be seen at figure 30.26 Derive and expression for the magnetic field produced at point P due to the current carrying wire shown in figure 30.26. The curved parts of the wire are pieces of concentric...

Homework Statement Homework Equations The Attempt at a Solution Is it an assumption because the difference in height is small?

Hi everyone, just wanted to know how does a soluble, volatile impurity affect the boiling point of a liquid? I know it depends on the difference between the boiling points of the liquid and the impurity, but I'm afraid i still didn't get the point. Thanks

Homework Statement Question: https://imgur.com/a/8rUw1 Graph: https://imgur.com/a/Z1oBO Homework Equations Answer for Q1 (Just the formula) : https://imgur.com/a/uesqN The Attempt at a Solution I have realized that from 1-2, there is an increase in pressure, decrease in volume and increase...

Homework Statement The dew point is the temperature at which moist air becomes saturated with water vapor. We can therefore represent how moist a particular parcel of air is by comparing its actual temperature with its dew point temperature. We see the practical effect of reaching the dew...

Homework Statement Two particles A and B each carry a charge Q and are separated by a fixed distance D. A particle c with charge q and mass m is kept at the midpoint of A and B. If C is displaced perpendicular to AB by a distance x where x<<<D, find the time period of the oscillation of the...

First, I must say I'm in no way a physicist, I barely understand the basics of quantum physics. And what I will talk about is mostly philosophical anyway. I don't believe myself that "we are in a simulation", it's just food for thoughts. As the title says, it's about 2 quantum things that struck...

Well, for starters, ##\pi(T)##, the fundamental group of the torus, is ##\pi(S^1)x\pi(S^1)=## which is in turn isomorphic to the direct product of two infinite cyclic groups. Before I tackle the case of n connect tori with one point removed, I'm trying to just understand a torus with a point...

Homework Statement Solve ##\Delta\phi = -q\delta(x)## on ##\mathbb{R}##. Correct answer: ##\phi = -\frac{q}{2}|x| + Ax + B## Homework EquationsThe Attempt at a Solution In one dimension the equation becomes ##\frac{d^2 \phi}{d x^2} = -q\delta(x)##. We integrate from ##-\infty## to ##x## to...

A weightless ladder 7.0 m long rests against a frictionless wall at an angle of 65° ablove the horizontal. A 72 kg person is 1.2m from the top of the lass. What horizontal force at the bottom of the ladder is required to keep it from slipping? Στ=0 τ=FsinθdSolutions for this question always...

Homework Statement Let ##(X,d)## be some metric space, and let ##f : X \to X## be such that ##d(f(x),f(y)) \le a d(x,y)## for every ##x,y \in X## for some ##a \in (0,1)## (such a map is a called a contraction map) If ##f## is a contraction and ##X## is compact, show that ##f## has a unique...

I get how to find vertical and horizontal forces on a submerged surface (vertical = weight of fluid and horizontal = force on vertical projection). I also get how to find the point of application for the horizontal force using a moment balance. But how do you determine the point of application...

$\textsf{write an equation for}$ $\textsf{ The plane through the point (3, 2, -5) and perpendicular to the x-axis}$ 4ok I know this goes thru $3$ on the axis and it is \parallel to the $yz$ plane so is it just $x=3$.

I am trying to learn all about Quantum Physics on my own but I am struggling to find credible sources of information. As you are probably aware the internet is filled with misconceptions, crackpot science and weird stuff about spirituality (at least that's what I find when I try and research...

I need help understanding point B Point A i get. Normal force at B = m x v2/r - m x g = 1.68 x 12 x 12 /5 - 1.68 x 9.8 = 31.92 N I can't make sense of why the forces are subtracting if A radial and MG are both positive

Homework Statement The question wants the total energy of point A. Point A is 35 m above the ground and the mass of the objecy is 150 kg. The velocity is 10m/s. (And point B is 20 m above the ground and point c is 26.) Homework Equations Ek= 1/2*mv^(2) Ep=mgh Total= Ek+Ep But for some reasons...

Homework Statement A uniform rigid bar of weight W is supported in a horizontal orientation as shown by a rope that makes a 30° angle with the horizontal. The force exerted on the bar at point O, where it is pivoted, is best represented by a vector whose direction is which of the following...

Homework Statement Given M: x(u,v)=β(u)+vδ(u) is a ruled surface with length(β')=1 and length(δ)=1, also supposing δ'≠0. M may be parametrized by y(u,w)=ϒ(u)+wδ(u), where ϒ'⋅δ'=0 (this reparametrization is called the line of striction). Show that any point on M that satisfies xu×xv=0 must lie...

There are two square scale. That is, it has marking where there are square i.e marking at 0,1,4,9,16,25 and so on. When one scale is moved, it slide over the other. Now if one scale is moved odd number i.e say 123 , that is, it's zero is placed at 123 over the other scale, now. Now, can one...

I'm trying to design something and rather than solve it using FEA guess and check, I'm trying to mathematically solve it. The part I'm getting stuck at is having 2 point loads on a linearly varying cantilever beam. https://imgur.com/LtHCvCB The closest example I could find to this that was...

<Moderator's note: Moved from a technical forum and thus no template.> Hello Forum, This post is a spin-off from this post: https://www.physicsforums.com/threads/how-much-would-time-pass-between-watching-the-sun-set.925257/#post-5840279 If I have an X and Y point on a grid that represents...

Homework Statement https://imgur.com/a/wpir4 [/B] a. What is the strength of the electric field at the position indicated by the dot in the figure? Use the following values: q1 = 1.09 nC, q2=0.93 nC, d1=2.49 cm, d2=6.9 cm, d3 = 4.27 cm. b. What is the direction of the electric field at the...

Homework Statement A mass point is sliding down from the top of a hemisphere, with an initial speed of zero. I want to determine the angle ##\theta## at which the mass point will lift off the surface of the hemisphere. Homework EquationsThe Attempt at a Solution We can determine the speed...

Hi guys, Do virtual particles, when they are fermions, obey Pauli exclusion principle as real fermions do? More specifically, what I am wondering is the following: Fermion fields would have some energy at every point in spacetime due to the uncertainty principle. Now, is it possible for the...