Harmonic Definition and 1000 Threads

Hi guys sorry if this is the wrong thread, I have a damped simple harmonic motion pictured below, i have to find the inerval t=0 and t=1 for which the amplitude of x(t) is considered to be zero. The behaviour of the graph below can be described as e^-kt cos(2πft) k=0.7s^-1 and f= 3Hz

Hi! As I outlined in my https://www.physicsforums.com/threads/hello-reality-anyone-familiar-with-the-davisson-germer-experiment.985063/post-6305937, I'm curious to ask if there is anyone with knowledge on the theory of the piezoelectric effect on this forum? I think it's fascinating how a...

c = Critically Damped factor c = 2√(km) c = 2 × √(150 × .58) = 18.65 Friction force = -cv Velocity v = disp/time = .05/3.5 Friction force = - 18.65 * .05/3.5 = -.27 N I am not sure if above is correct. Please check and let me know how to do it.

I know that ahat_+ = 1/sqrt((2*m*h_bar*w)) * (mw(xhat)+i(phat)) and ahat_- = 1/sqrt((2*m*h_bar*w)) * (mw(xhat)-i(phat)). But I'm not sure what (ahat_+)^+ could be.

I am reading "Coulomb and the evolution of physics and engineering in eighteenth-century France". There it is said in page 152 para 1 that "Coulomb found that within a very wide range, the torsion device oscillated in SHM". My questions are: (1) By just looking at the time period of the...

Using A = x0, B = v0/ω I get ω = 4π, A = 1, B = 1/4π then converting to phase/magnitude form \sqrt{A^{2} + B^{^{2}}} = \alpha \sqrt{1^{2} + \left ( \frac{1}{4\pi }\right )^{^{2}}} = \alpha = \frac{1}{4\pi }\sqrt{16\pi^{2} +1} However the answer in the back of the book has α = 1 Is...

I don't quite understand how he got the line below. By using discrete time approximation, we can get the second order time expression. But i don't see how by combining terms he is able to get such expression.

For part (a), which generic function would be used? either y = f(x) = ASin(2πft + ϕ) or y(x,t)−y0=Asin(2πft±2πx/λ+ϕ) ?? Furthermore how to find out max. speed & max. acceleration of a point on the string?? Any directions please

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inertia of center = [(1/12) m*L^2 + m(L/2)^2]*4 inertia of center = (4m*L^2)/ 3 inertia around pin = (4m*L^2)/ 3 + 4m(L/ 2^(1/2) )^2 inertia around pin = (10m*L^2)/ 3 inertia around pin = (10*0.1*1^2)/ 3 = 0.33 kg*m^2 d= 1/2^(1/2) = 0.707m (m*g*d/inertia)^1/2 = 2pi/period...

I'm working through https://ocw.mit.edu/courses/physics/8-05-quantum-physics-ii-fall-2013/lecture-notes/MIT8_05F13_Chap_06.pdf, and I'm stumped how they got from Equation 5.26 (##\vert 0_{\gamma} \rangle \equiv \frac{1}{\sqrt{cosh\gamma}} exp(-\frac{1}{2}tanh\gamma \hat{a^\dagger}\hat{a^\dagger}...

I can show that ##\frac{d}{dt} \langle \psi (t) \vert X^2 \vert \psi (t) \rangle = \frac{1}{m} \langle \psi (t) \vert PX+XP \vert \psi (t) \rangle##. Taking another derivative with respect to time of this, I get ##\frac{d^2}{dt^2} \langle \psi (t) \vert X^2 \vert \psi (t) \rangle = \frac{i}{m...

I am currently having trouble deriving the volume element for the first octant of an isotropic 3D harmonic oscillator. I know the answer I should get is $$dV=\frac{1}{2}k^{2}dk$$. What I currently have is $$dxdydz=dV$$ and $$k=x+y+z. But from that point on, I'm stuck. Any hints or reference...

An electric field E(t) (such that E(t) → 0 fast enough as t → −∞) is incident on a charged (q) harmonic oscillator (ω) in the x direction, which gives rise to an added ”potential energy” V (x, t) = −qxE(t). This whole problem is one-dimensional. (a) Using first-order time dependent perturbation...

I have the formula for amplitude ##A=\sqrt (x_0^2 + \frac{\dot x_0 ^2}{\omega^2})##. But ##x_0## and ##\dot x_0## refers to the initial conditions, and the information that I'm given is not related to the initial conditions, or at least I'm not told so.

Well, this is a problem which makes you think more about concepts than numbers, so I want to see if I've done it correctly. 1) I draw a simple pendulum in an elevator, where you have weight, tension and a pseudo-force. In this situation the effective gravity may be changing due to different...

If I write Newton's equations, seen inside the room and with non tilted axis we have: ##x) N.sin(\alpha)-Fe.cos(\alpha)=m.a_x## ##y) N.cos(\alpha)+Fe.sin(\alpha)-m.g-f*=m.a_y## Where ##f*=ma##, ##Fe## is the elastic force. Then, how can I realize about simple harmonic motion? I also can think...

For a harmonic oscillator with a restoring force with F= -mω2x, I get that the solution for the x-component happens at x=exp(±iωt). But why is it that you can generalise the solution to x= Ccosωt+Dsin(ωt)? Where does the sine term come from because when I use Euler's formula, the only real part...

In the paper below I've seen a new method to solve the quantum harmonic oscillator Introduction to the Spectrum of N=4 SYM and the Quantum Spectral Curve It is done using the concept of quasi momentum defined as $$p = - i \frac{d(\log \psi)}{dx}$$ See pg 7,8 Is this well know? is it discussed...

I posted yesterday but figured it out; however, a different issue I just detected with the same code arose: namely, why does the solution damp here for an undamped simple harmonic oscillator? I know the exact solution is ##\cos (5\sqrt 2 t)##. global delta alpha beta gamma OMEG delta =...

Dear PF community, I am back with a question :) The solutions for the quantum harmonic oscillator can be found by solving the Schrödinger's equation with: Hψ = -hbar/2m d²/dx² ψ + ½mω²x² ψ = Eψ Solving the differential equation with ψ=C exp(-αx²/2) gives: -hbar/2m (-α + α²x²)ψ + ½mω²x²ψ = Eψ...

I am reading an interesting book by Julian Havil called:" Gamma-Exploring Euler's Constant." Much of the book is devoted to the harmonic series,a slowly diverging series that tends toward infinity.However,one paragraph puzzles me. On p. 23 he says: " In 1968 John W. Wrench Jr calculated the...

My workings: ##D(t) = Asin\omega t## ##v(t) = \frac{\text{dD}}{\text{dt}}=Acos(\omega t)\omega## ##v(t) =Acos(\omega t)\omega## When displacement half of amplitude, ## Asin\omega t## = 0.5##A## ## sin\omega t## = 0.5 ##v(t) =Acos(\omega t)\omega## ##v(t) =\omega (0.5Asin\omega t)cos \omega t ##...

The wavefunction is Ψ(x,t) ----> Ψ(λx,t) What are the effects on <T> (av Kinetic energy) and V (potential energy) in terms of λ? From ## \frac {h^2}{2m} \frac {\partial^2\psi(x,t)}{\partial x^2} + V(x,t)\psi(x,t)=E\psi(x,t) ## if we replace x by ## \lambda x ## then it becomes ## \frac...

I cannot find the correct answer anywhere online and the answer I keep getting is 5.4 (incorrect) Please show me the process to get to the answer! Thank you

Hey, I solved a problem about a double pendulum and got 2 euler-lagrange equations: 1) x''+y''+g/r*x=0 2) x''+y'' +g/r*y=0 (where x is actually a tetha and y=phi) the '' stand for the 2nd derivation after t, so you can see the basic harmonic oscillator equation with a term x'' or y'' that...

I'm reading through Lancaster & Blundell's Quantum Field Theory for the Gifted Amateur and have got to Chapter 17 on calculating propagataors. In their equation 17.23 they derive the expression for the free Feynman propagator for a scalar field to be...

i have started by taking the rms values of the results from the spreadsheet making: I1= 2.818 amps I3=2.095 amps I5=1.767 amps i then added I3 and I5 to give me 3.863 amps which i then input into the formula to yield a result of 135.202% which seems way off to me, any help would be greatly...

As we see in this Phet simulator, this is only the real part of the wave function, the frequency decreases with the potential, so lose energy as moves away the center. we se this real-imaginary animation in Wikipedia, wave C,D,E,F. Because with less energy, the frequency of quantum wave...

The graph provided is below. The problem asks for the speed of the wave at 0.12s. I used the formula v=w*xmax*cos(wt), provided in our textbook where xmax is the amplitude of 2 cm, w (omega) is 2pi divided by the period of 0.2. However, for some reason this formula doesn't give me the correct...

Moved from technical forum, so no template is shown Summary: I have the expression sin(2x) + sin(2[x + π/3]) and I have to write this in terms of a single function (a single harmonic, rather saying). But I don't know how to do this, and... it seems a little bit weird for me, because I'm merging...

I divide by zero which is a no-go, but on the other hand: at resonance frequency the phase-shift is 90 degrees.

It is true that at resonance frequency the phase-shift between input and output is 90 degrees, so my mind would think that this is ok. But I am kind of unsure because of the whole dividing by zero part. If this isn't allowed: is there any way to calculate/measure the damping coefficient with...

Hi, for ease of reference this posting is segmented into : 1. Background 2. Focus 3. Question 1. Background: Regarding (one, linear, second-order, homogeneous, ordinary, differential) equation describing the force in a non-driven, damped oscillation: F = m.a = -k.x - b.v F =...

I think you could try to solve for the forces based on when the spring falls from an incline at various angles theta, but I am not sure. Or spring potential energy? I'm really confused. Is there any other method? Could it involve using water and wave harmonics? (We learned waves and sound...

The answer is f/square root 2 If F = 1/2l * square root ( Tension/ mass per unit length ) ---------> this becomes I am assuming 1/2l * square root ( length * Tension/ mass ) this would give an answer of F yet the answer is F/ square root (2)

First, I decided to solve for the coefficient in front of the cosine simple harmonic function for velocity. I know there is max velocity of 30cm/s at time = 0 , so I plug it into velocity function. xmax * w = A v(t) = Acos(wt) 0.3 = Acos(w*0) A = 0.3 Then I have my velocity function...

I've been going to the theme park almost every year-and this year in my Physics class we are learning mechanics, more specifically Simple Harmonic Motion. My teacher told us that for an object to have 'Simple Harmonic Motion' it must have oscillatory motion (like a pendulum going back and...

Hi, I am unsure how to proceed with this problem. I believe that I can correctly calculate the frequency of the oscillations for a bar that is not suspended from a spring but I do not know how to take the effect of the spring into account. The answer given by my professor is $$...

I started off by finding when Fg=Fx: (72)(x)=(31)(9.8) x=4.2193m After this I'm stuck and have a few things I'm confused about: When the penguin's jumping, is there elastic energy? (because the rope's getting compressed? Or maybe not). Also, I know you can use energy conservation, but...

I know that due to causality g(t-t')=0 for t<t' and I also know that for t>t', we should get g(t-t')=\frac{sin(\omega_0(t-t'))}{\omega_0} But I can't seem to get that to work out. Using the Cauchy integral formula above, I take one pole at -w_0 and get \frac{ie^{i\omega_0(t-t')}}{2\omega_0} and...

First of all, I found a function of the distance of the object form the equivalence point in both cases. I got something like d=2d' where d is the distance at the first case and d' at the second. I did that because I wanted to find the frequency, and so first I need to find the period of...

I was reviewing the harmonic oscillator with Sakurai. Using the annihilation and the creation operators ##a## and ##a^{\dagger}##, and the number operator ##N = a^{\dagger}a##, with ##N |n \rangle = n | n \rangle##, he showed that ##a | n \rangle## is an eigenstate of ##N## with eigenvalue ##n -...

Homework Statement https://imgur.com/lGas78X The solution to this question says 450Hz. However, when I attempted to compute the frequency using the wave equation and find the normal mode solutions, I get 750Hz 2. Homework Equations I suspect that the solution could be wrong, is that the...

I'm in trouble trying to understand the expression ##t= \frac{1}{\omega} cos^{-1}(x/A)## that comes from ##x = Acos(\omega t)##, in which ##A## is the amplitude, ##t## is time and ##x## is displacement. When ##x = 0##, ##t = \frac{\pi}{2\omega} ##, shouldn't it be 0 since there was no movement?

Homework Statement I'm trying to reconcile the answers to two questions regarding the average potential and kinetic energies in simple harmonic oscillator Question 1: The average potential energy of the vibrational motion in the ground state of a diatomic molecule is 12 meV. The average...

Homework Statement Harmonically fluctuating object. It`s full energy (E) is 3*10-5 J. Maximum force (F) on object is 1.5 * 10-3N. Period is 2 seconds (T) and starting phase (ƒ) is 60°. Need to write equation for these fluctuations. E = 3*10-5 J F= 1.5 * 10-3N T = 2 s ƒ = 60° Homework Equations...

How can I find omega on an object that is floating on water which is moving up and down on the object? The problem goes by giving you a cylindrical object with radius r and height H, pw(density of water), pc(density of circle) and x(t)=a*cos(wt). I do not understand why pw*pi*r^2*dg=pc*pi*r^2Hg

Reading this piece with a number of proofs of the divergence of the harmonic series http://scipp.ucsc.edu/~haber/archives/physics116A10/harmapa.pdf and this example states: 'While not completely rigorous, this proof is thought-provoking nonetheless. It may provide a good exercise for students...

Homework Statement For any harmonic load: $$F(t)=F_0\cdot \sin(\omega t)$$ What is the corresponding Frequency domain equivalent? My lecture notes is suggesting: $$ F(t)=F_0 \cdot e^{i \omega t} $$ But I am failing to see how they are equal? The lesson is about Stochastic Response of...