Relationship Definition and 999 Threads

This is the question: What is electromotive force? What's its relationship to Voltage? + clarification of confusion If you believe you have a good answer, please answer either in this website or in Stack Exchange.

I was doing a thought experiment on the harmonic mean. Let's say we have a sequence of 4 numbers: 100, 110, 90, 100 The arithmetic mean (AM) of this sequence is 100 but the harmonic mean (HM) is 99.4975. Let's imagine that the initial and final values remain constant but the middle ones get...

In statistical modeling, the goal is to come up with a model that describes the relationship between random variables. A function of randoms variables is also a random variable. We could have three random variables, ##Y##, ##X##, ##\epsilon## with the r.v. ##Y## given by ##Y=b_1 X + b_2 +...

I am a newbie and the last time I did physics was in secondary school. I was researching the topic of pi and came across the euler's constant and was wondering about the relationship between euler's constant and the speed of light specifically ce². I think that works out to be one third the...

Its form is: (n2-1)/(n2+2)=(4π/3)Nam There is one simple problem with it. Rearrange the left side and you get: (n2+2-3)/(n2+2)=(4π/3)Nam 1-(3/(n2+2))=(4π/3)Nam As you see, the left side cannot reach unity for arbitrarily large n2. But there is no reason why N cannot be arbitrarily large! How...

Hi all, While calculating the surface area for an object, I was told the below statement. However, I am not sure is this correct, please can someone help me to explain this with an example? Is the below statement always true? The surface area % increase should be in line or less than the %...

In the popular answer for the coin-mass question of Physics Stack Exchange, I am wondering what are the correlation between the first red peak at around 9kHz and the second red peak at 16kHz. I first thought that they are consecutive harmonics but there was no way of proving it as I do not know...

Picture below. Both bodies are made of same material but the body placed in water had 2.4 times greater mass. What is the relationship between buoyancy Force and gravitational force between body in water and body in air?I have no clue how to solve this. I know that body with greater mass has 2.4...

As stated in the problem, I want to demonstrate mathematically that field line density is directly related to the magnitude of B. How would I be able to do this, other than simply using the flux equation and showing that for a higher flux in the same area, the magnetic field must be rise...

my solution: a) F(upward)=Fb +Fw =(1.3+1.5)X9.8 =27.44N total Mass = 2.8kg b) Volume increased = π(0.2/2)^2 x 1.5/100 =4.7x10-4 m^3 T+Fb =mg T=mg-Fb T=2.2x9.8 -1000 x 4.7x10-4 x 9.8 T=17.4N T is the apparent weight of the rock, so the mass of the rock in the water...

hello, I read in a lecture paper about fluid mechanics that velocity is not related to viscosity, i found this odd and i think it is an error , can someone confirm that?

I am wondering if it is possible to calculate either the Kinetic Energy or Rotational Kinetic Energy of an object if we have the Power (kW), Torque (Nm), and Speed (RPM) of the object.

I am currently studying to solve Maxwell's equations using FEM. I have a question about Maxwell's equations while studying. I understood that the magnetic potential becomes ▽^2 Az = -mu_0 Jz when the current flows only in the z-axis. I also understood the effect of the current flowing in a...

Hey I have a question about the relation between Legendre transformation and Hamilton-Jacobi formalism. Is there some relation? Cause Hamilton-Jacobi is the expression of Hamiltonian with a transformation.

As I understand it, the flatness problem of Bob Dicke, says a flat universe in unstable and so has to be set very precisely in the early universe to give us the flat universe we see today. Is this the same problem as saying the expansion rate had to be finely tuned and if so how are the two...

What is it the we detect in the first instance? Is it the particle |wave or is it the field? Is the former more fundamental than the latter in any sense or are we just talking the opposite sides of the same coin? For instance does the em field create the photon and the electron or could...

I have taken a Quantum Field Theory course recently in which we first derived the Callan-Symanzik equation and then discussed Wilson's Renormalization. However, I don't think I have a clear understanding of the procedures and how they relate to each other. For the sake of this question, let's...

Answer: Did I draw them right?

Won't go into specifics, but we got into a bit of an argument (originally over some quite harmless things mentioned by some of my friends at dinner) resulting in me walking out at around midnight and ignoring her calls. When I got back home she was crying outside so I went to comfort her and to...

I need some help understanding shock waves, particularly the units of measure related to their pressure. Shock waves are frequently quantified as multiples of G, the gravitational constant. I need to understand how the G measurements related to the instantaneous pressure within the wave as...

I think the answer is that the elastic potential energy will be a 1/16th of the original value. This is my reasoning: 1) If the diameter doubles, the cross sectional area is 4 times the original value. (from A= πr2). 2) F= stress/area. Force (load is the same). If cross sectional area...

Suppose I have some interaction potential, u(r), between two repelling particles. We will name them particles 1 and 2. I want to find the force vectors F_12 and F_21. Would I be correct in saying that the x-component of F_12 would be given by -du/dx, y-component -du/dy etc? And to find the...

I found that I had an inaccurate understanding of their relationship earlier. After rethinking, I try to express their relationship in a simple and understandable way Nuclear reactions convert energy from form of mass to form of light, and both energy and momentum are conserved during the...

Assume that the lengths of various sections of the string at an instant are as shown. So we can say that ##l_1 + l_2+l_3= k## at an instant of time ##t##, where ##k## is a constant. Taking the second derivative of both sides w.r.t. ##t##, we get $$\frac {d^2{l_1}} {dt^2} +\frac {d^2{l_2}} {dt^2}...

[url="https://www.physicsforums.com/insights/the-amazing-relationship-between-integration-and-eulers-number/"]Continue reading...

I wonder if someone please could explain what the relationship between a spectral line strength and gravity is? Does the equivalent width of e.g. Ca II decrease with increasing gravity? what kind of processes affects the strength of a line if we change the gravity of a star? Hope you can help me

Hi, Originally, the absolute temperature was thought to be around -273 Celsius around 1750 and it was the result extrapolation of of ideal gas law as shown below. I find it hard to phrase my question. But the question is how come they were so confident that the relationship between the volume...

Hi all I have a very quick question I'm trying to understand why a graph of Rebound height (m) vs Air Pressure (x axis) doesn't have a line of best fit which goes through the origin. I understand a basketball's bounce can be compared to the compression of a mass-spring system but then why...

Was fooling around and wrote down these two equations today that appear to work. I'm not all that bright and I'm positive these either have some proof or restate some conjecture--probably something in a textbook. Could somebody help me out? \forall n \in \mathbb{N}_0\smallsetminus\{0\} n^2 =...

One recent example of a thread discussing flat or not is: https://www.physicsforums.com/threads/could-the-universe-be-infinite.1011228/ . I found an interesting 2021 article regarding the Hubble constant tension...

(a) Knowing ##E##, we can use equation (2) to determine ##V##. However, since ##\vec E## represents the distribution of electric field in space i.e. a function of (x,y,z). For example, ##\vec E = x \hat i + y \hat j + z \hat k##. Here we do not know this function so how can we know ##V## at a...

c) Why is the assertion ##\lim\limits_{x \to 0} f(x) = \lim\limits_{x \to 0} f(x^3)## obvious? First of all I don't think it is obvious but here is an explanation of why the limits are the same. ##\lim\limits_{x\to0} f(x^3)=l_2## means we are looking at points with ##x## close to zero and...

Physics novice here reading pop sci cosmology. Please bear with me. Premise 1: Whether or not expansion is slowing down or speeding up depends on a battle between two phenomena: the attractive gravitational pull of matter and the repulsive gravitational push of dark energy. What counts in this...

I have following setup where a non-elastic belt is wrapped around an elastic object, like leather belt around waist. When I pull the belt with force F, it tightens around the elastic object and the belt exerts force to the elastic object. I would like to know what is the relationship between the...

I know you find the static friction of an incline by raising it until it begins to move and then measure the tangent of that angle, but I'm not sure how I'm supposed to show a relationship or create a procedure based off that.

Okay so this is how it looks like,and there are the given values; a) I've tried it like this. So I now this formula $$ E = \frac{J}{\sigma} $$ where sigma is the conductivity value. Now to get E we need this formula; $$ U = \int_{l}{} E \ ds ] $$ Now to get U we can use the ## U = \frac{P}{I}...

I would like to conduct an experiment asking the question "how does the angle at which a projectile is launched vary with respect to the horizontal range it covers?" Ultimately, I'd like to prove that the horizontal range is directly proportional to sin(2(theta)). This will be done with the aid...

I have a quick question. If a Vector is contained inside a plane, would the normal of the plane be orthogonal to said vector? Thank you!

Given a 1D heat equation on the entire real line, with initial condition ##u(x, 0) = f(x)##. The general solution to this is: $$ u(x, t) = \int \phi(x-y, t)f(y)dy $$ where ##\phi(x, t)## is the heat kernel. The integral looks a lot similar to using Green's function to solve differential...

Hi, I'm working on a project to see if deliveries, pick ups, or both combined are better for the environment / more energy efficient / more time efficient. For example, (a) everyone collecting from a farm by bike, (b) vans bringing to supermarkets and then people collecting from supermarkets, or...

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Quantum mechanically, a spin 1/2 particle in a uniform magnetic field has two energy eigenstates ##\ket{up}## and ##\ket{down}## and rotational degrees of freedom (distinct from the energy eigenstates) about the axis of the magnetic field. this can be derived from the Pauli matrix commonly...

According to the wiki entry on Planck units, https://en.wikipedia.org/wiki/Planck_units, the energy density of the universe, 1.8 × 10−123, is 1/16th the cosmological constant, 2.9 × 10−122. Is there a theoretical reason for this precise relationship?

I performed an experiment where I let water flow out of a measuring cylinder through a hole at the base of the measuring cylinder. I let the water run out for 30s, recording the volume after. I did this for different heights of water in the measuring cylinder, and kept the pressure of water at...

What is the relationship between the electromagnetic field and space-time? I am basically assuming that space-time is one big gravitational field. Is there a relationship between space-time and the field (I presume) created by the strong force (however negligible it may be at any significant...

Find a relationship between x and y such that (x, y) is equidistant (the same distance) from the two points. Our two points: (6, 5), (1, −8) No sample question is given by Ron Larson for this problem in the textbook. I need a set up. I will do the math, of course.

I'm trying to figure out how to relate expected thermal expansion of a uv cured polymer within a rigid cylinder to a modulus specification. The issue is the expected change in refractive index due to thermal expansion. The expansion coefficients are not available. Anybody have an idea. Do...

What does it mean that the relationship between material mass and weight is constant and proportional? Hi! Yes, another question... I have many doubts. :) I hope someone can help me with this apparently very basic doubt, but I feel like a stupid monkey trying to join two sticks to reach bananas...