Demonstration Definition and 126 Threads

https://www.physicsforums.com/threads/what-high-paying-low-competition-jobs-fields-can-a-recent-grad-in-electrical-engineering-go-into.1060281/ Any utility to the inclusion & dispositions of "sample trolls/trolling" in terms of demonstration(s) to/for newcomers that PF did NOT just recently...

So I'm watching this demo posted in another problem by @PeroK by Prof. Walter Lewin and I can't help but see that in the part where he is demonstrating the independence of acceleration cylinder length that the (presumably) shorter aluminum cylinder is edging out the win...Not intended, but...

I want to demonstrate that calculating the squared amplitude of the process quark antiquark in lepton antilepton where I consider the non-zero masses of the fermions, is equivalent to considering the zero masses but with infinite insertions of the vev. I am trying to do it, but the pieces I find...

I'm trying to do a demonstration of chaotic systems for college students. If anybody knows where I can find a desktop double pendulum online / how I can DIY one without woodworking that'd be much appreciated. I did find the "swinging sticks kinetic sculpture", but I'd prefer a more classic...

(a) Let be m a line and the only two semiplans determined by m. (i) Show that: If are points that do not belong to such , so and are in opposite sides of m. (ii) In the same conditions of the last item, show: and . (iii) Determine the union result , carefully justifying your answer...

This is a demonstration on what he there calls a Graphene piano. I DO NOT BELIEVE THIS, in all honesty; unless someone here can instruct me differently:

Hello, is there a convincing experiment to visualize absorption spectra? At disposal I have: - Halogen lamps - Lenses - Straight view prism - transmission grating - slit, iris, screen - Sodium vapor lamp and mercury vapor lamp Unfortunately, I do not have a sodium vapor cell or anything...

So in class today, we were talking about how if you fire a bullet aimed at a falling target and release the target and the bullet at the exact same time, they will surely collide. I asked if air resistance (since it’s not a constant force) wouldn’t affect the collision and my teacher didn’t have...

Just to remind, ##C_\ell## is the variance of random variables ##a_{\ell m}## following a Gaussian PDF (in spherical harmonics of Legendre) : ##C_{\ell}=\left\langle a_{l m}^{2}\right\rangle=\frac{1}{2 \ell+1} \sum_{m=-\ell}^{\ell} a_{\ell m}^{2}=\operatorname{Var}\left(a_{l m}\right)## 1)...

I'm looking for a collection of physics video demonstrations (open sourced or licensed) for an online calculus-based class at the level of Halliday, Resnick, Walker textbook, covering EM waves, optics, special relativity, intro to quantum, and so on, basically the last third of the textbook. I...

Here is an interesting YouTube video explaining what happened with the most recent Astra launch. One of five rocket engines failed almost immediately. According to the video, this left the rocket with a thrust-to-weight ratio of 1.00 until the fuel burned off. But it took about 10 seconds...

Hello, In this thesis https://tel.archives-ouvertes.fr/tel-01743877/document at "1.2.2 Bell inequalities" page 7-8 it's define a correlation function : C(x y) = P(+ + |x y) + P(− − |x y) − P(+ − |x y) − P(− + |x y), with −1 ≤ C(x y) ≤ 1. How do one get to this relationship −1 ≤ C(x y) ≤ 1 ...

What are the best options for buying physics classroom demonstration equipment (e.g., air track, optics, etc.)? There seems to be several options/sellers out there, but it also looks like the quality of equipment varies. It is hard to tell from the online photos and descriptions what sources are...

Hello, everybody: I am a philologist who is fond of mathematics, but who unfortunately has just an elementary high school knowledge of them. I am translating La leçon de Platon, by Dom Néroman (La Bégude de Mazenc, Arma Artis, 2002), which deals with music theory and mathematics in the works of...

I've just studied simple pendulum: The simple pendulum (for small oscillations) differential equation is first image. I've no problem to arrive this result and formula. My problem is to get to the second formula by passing through another formula (Image 3) that my book mentions. I can't...

Helo, The Lagrangian in general relativity is written in the following form: \begin {aligned} \mathcal {L} & = \frac {1} {2} g ^ {\mu \nu} \nabla \mu \phi \nabla \nu \phi-V (\phi) \\ & = R + \dfrac {16 \pi G} {c ^ {4}} \mathcal {L} _ {\mathcal {M}} \end {aligned} with ## g ^ {\mu \nu}: ## the...

I've just learned about simple harmonic motion and I've been given the following examples: The physical pendulum (for small oscillations sin(theta)~theta), with the formula (1st pic), and the LC circuit, with the formula (2nd pic). If possible, I need the demonstration for these 2 formulas...

1) I can't manage to find/justify the relation ##(1)## below, from the common relation ##(2)## of a volume. 2) It seems the variable ##r## is actually the comoving distance and not comoving coordinates (with scale factor ##R(t)## between both). The comoving volume of a region covering a solid...

The Kirchhoff law of dependence of energy emitted from a blackbody only on wave length and temperature was demonstrated by Kirchhoff in a paper in the year 1859. The paper is in german naturally but I found it translated in english in a book of prof. Brace in 1901. A lot of time ago. But my...

Hi, I am working on a video, and I was wondering if any of you knew of some real-life demonstrations I can do about black holes? So far I have the gravity well, and the balloon covered by foil that you crush to show same mass but denser. My video is about the anatomy of a black hole, so I cover...

Is there a machine that can emit multiple radio waves simultaneously? I am trying to create a demonstration, but it requires multiple radio waves at once and cannot find any machines that can do so.

I found, at least in my uneducated opinion, a very good demonstration of water as a dielectric. I understand that putting water in a bag will change the dielectric constant of the water in it somewhat, but I think the capacitance meter at least makes water's value as a dielectric visually...

I am reading a book of General Relativity and I am stuck on a demonstration. If I consider the FLRW metric as : ##\text{d}\tau^2=\text{d}t^2-a(t)^2\bigg[\dfrac{\text{d}r^2}{1-kr^2}+r^2(\text{d}\theta^2+\text{sin}^2\theta\text{d}\phi^2)\bigg]## with ##g_{tt}=1##, ##\quad...

I find directional derivatives confusing. For example if there is a change in a direction and if this direction have both x and y components should not the change be calculated as square root of squares, i.e the pythogores theorem? Would you please provide a simple demonstration showing the...

At high school, we saw without demonstration the fundamental principle of dynamics (2th Newton's law), i.e : $$\sum \vec{F}=m \vec{a}\,\,\,\,\,\,\,\,\,eq(1)$$ after, at university, we saw another expression of this 2th Newton's law : $$\sum \vec{F}= \dfrac{d\vec{p}}{dt}\,\,\,\,\...

I want to design an experiment to demonstrate Raman - Nath effect. Due to limited resources at my hand (my school doesn't have too much resources), my condition is somewhat like Raman, and hence I want to do the original experiment that Raman and Nath conducted in IISc Bangalore back in the...

I try to find the formula of dilation of time between a reference frame (R') moving at a speed v and a fixed observer in (R). For this, I take the example that we often find as a demo : that of a train in which a light beam is emitted vertically (in the train): this vertical trajectory in the...

Homework Statement Let ##\alpha \in \mathbb{R}## and ##n \in \mathbb{N}##. Show that exists a number ##m \in \mathbb{Z}## such that ##\alpha - \frac {m}{n} \leq \frac{1}{2n}## (1).The Attempt at a Solution If I take ##\alpha= [\alpha] +(\alpha)## with ##[\alpha]=m## (=the integer part) and...

Hello There is the possibility that they help me to solve this demonstration. please AX(BΔC)=(AXB)Δ(AXC)

Homework Statement [/B] In the equation between (3) and (2), why does the author says that ? Isn't the trigonometric identity actually ? 2. Homework Equations The Attempt at a Solution

Hello, Einstein evaluated the size of an atom by analysing a brownian motion, assuming the size of the molecules is a a factor. In order to demonstrate this concept, I want to put some powders with different sizes of grains on a vibrator and watch how a ball moves. What is the expected result...

In thousands of years time (when we have the technology to do almost anything) what would be the ideal demonstration of time dilation? Imagine I am a child. ps. Sorry if this post is over speculative. Feel free to move it if that helps.

We have all seen the marshmallow peep inside a vacuum chamber grow and them shrink. I want to convey the importance of Space suits and protecting the human body by creating a sort of "space suit" for a peep to wear or get placed inside of while in a vacuum chamber, so it is protected from the...

Hello. Given a range of time in which an event can occur an indefinite number of times, we say a random variable X folows a poisson distribution when it follows this statements: X is the number of times an event occurs in an interval and X can take values 0, 1, 2, … The occurrence of one event...

So I need to give an exciting thermodynamics demo based on one of the first two laws. I have found it difficult to either make it exciting enough or to make it apply to thermodynamics enough. I have a few that I have come up with but I don't think any really apply as well as I want. 1)Can...

Homework Statement Good morning or afternoon everybody. I am trying to calculate the commutator between two components of angular momenta by following somebody's steps. During the process, I arrive to one step which I can't follow. It's between before and after the equal. Σnml ∈jnm∈kln iħ...

Homework Statement let be ABC a generic triangle, build on each side of the triangle an equilater triangle, proof that the triangle having as vertices the centers of the equilaters triangles is equilater Homework Equations sum of internal angles in a triangle is 180, rules about congruency in...

Ok, So I'm bulding a prototype of a hydropower plant, that will be used to teach kids. I have NO CLUE about what generator to use. So here's how it works (check the attached pic): - We have a water tank - A pump pulls the water from the tank - the water is used in a pelton wheel - a generator...

Homework Statement Hi there. I have to prove this inequality: ##||x||_2 \leq ||x||_1 \leq \sqrt{n} ||x||_2## Where ##||x||_2## is the ##l_p## norm with p=2, so that: ##||x||_2=(|x_1|^2+|x_2|^2+...+|x_n|^2)^{\frac{1}{2}}## And similarly ##||x||_1=|x_1|+|x_2|+...+|x_n|## is the ##l_1##...

I'm a senior in high school taking AP Physics II, and I was recently elected as the president of my schools Science Club. Our first thing to do is to go to the local elementary schools and give interesting physics demonstrations to the younger students grades K-6. I really enjoy space and I know...

I can't figure out why my demonstration of snell's law fails, that's the demonstration: (I used a photo) I think it fails because the function t (HO) represents a line and so the concept of minimum is not defined, when I take the derivative and equal it to 0 I'm considering the case when the...

Hello everyone, I am working on the Onsager reciprocal relations, more precisely on the demonstration of those relations. I try to understand the Onsager original paper (1931) but it's really not easy (although he says that the examples are "extremely simple"). I was wondering if any of you...

Why in first order logic theories are not possible a demonstration with infinite steps?

Ouch! http://metro.co.uk/2015/04/01/when-physics-lessons-go-wrong-they-go-very-wrong-5130079/ Anyone has any follow-up info on this? The YouTube video has a title that implied that the teacher lost his job for this. There's also confusion on the unfortunate person who got hit if he was a...

ABSTRACT: I have a collection of springs and disks (masses) to choose from. I have a solid rod fixed to the ground. I slide a piece of sheet metal into the rod to act as a base. I now slide a disk into the rod. Then a spring. Then another disk. Then another spring. And one final disk. I now lift...

I'm stucked in a passage of Particle Physics (Martin B., Shaw G.) in page 41 regarding neutrino oscillations. Having defined E_i and E_j as the energies of the eigenstates \nu_i and \nu_j, we have: E_i - E_j = \sqrt{m^2_i - p^2} - \sqrt{m^2_j - p^2} \approx \frac{m^2_i - m^2_j}{2p} It...

Hello, I have been trying to do an assignment for one of my physics class. We are trying to demonstrate the planetary motion using Kepler's law. I have been trying to solve a integral. I was able to solve it using maple. I am trying to solve equation 29 in attached figure. I got equation 31...

I hope that the title is a bit better than my last one... I would appreciate any input on items I have made or will be demonstrating as it should be about 30 minutes long and a balanced programme. Background... I am in training as an Assistant Beaver Leader in my Sons Beaver cubs scout pack...

I need to perform a demonstration of electric forces. Something more substantial than weak static charge forces would be best. Could someone please help me by describing a practical way for me to put a charge onto something lightweight and then generate an electric field to move it back and...

Someone can demonstrate me why ##Re(z) = \frac{1}{2} \left ( z+\bar{z} \right )## ##Im(z) = \frac{1}{2i} \left ( z-\bar{z} \right )## ##Abs(z)=\sqrt{z\bar{z}}## ##Arg(z)=-i ln\left ( \frac{z}{\sqrt{z\bar{z}}} \right )## ? 2# Is correct to affirm that ##Arg(z)=-i ln\left...