What is Oscillations: Definition and 517 Discussions

Oscillation is the repetitive variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. The term vibration is precisely used to describe mechanical oscillation. Familiar examples of oscillation include a swinging pendulum and alternating current.
Oscillations occur not only in mechanical systems but also in dynamic systems in virtually every area of science: for example the beating of the human heart (for circulation), business cycles in economics, predator–prey population cycles in ecology, geothermal geysers in geology, vibration of strings in guitar and other string instruments, periodic firing of nerve cells in the brain, and the periodic swelling of Cepheid variable stars in astronomy.

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12. Oscillations of a disc with a smaller disc removed (Feynman ex. 17.23)

A disc of radius ##a## has a smaller disc of radius ##a/2## removed. The resulting object has mass ##m##: The centre of mass ##G## is a distance ##h = \dfrac{\pi a^3 - \dfrac{3\pi a^3}{8} }{\dfrac{3\pi a^2}{4}} = \dfrac{5a}{6}## from the edge. The moment of inertia of the shape about the...
13. I What Happens to Energy When Phonons are Damped?

If you go beyond the harmonic approximation, phonons can not be thought as independent quasiparticles anymore and phonon-phonon interactions are taken into account. This eventually translates into the fact that phonons frequencies get renormalized ( ##\omega \rightarrow \omega^′ +i\nu ##)...
14. Derive the period of a Ball rolling in a Bowl

The following attempt gives the wrong answer, and I would like to know where it goes wrong. Let ##\theta## be the angle of the ball with the vertical passing through the centre of the bowl, and ##\phi## be the angle the ball rolls through. Let ##m## be the mass of the ball, ##r## be the radius...
15. Equations of motion of damped oscillations due to kinetic friction

Take rightwards as positive. There are 2 equations of motion, depending on whether ##\frac {dx} {dt} ## is positive or not. The 2 equations are: ##m\ddot x = -kx \pm \mu mg## My questions about this system: Is this SHM? Possible method to solve for equation of motion: - Solve the 2nd ODE...
16. Oscillations in an LC circuit (Question from Irodov)

https://www.physicsforums.com/attachments/282131
17. What is the "free charge" in Langmuir oscillations for T>0?

I did a homework problem in plasma physics recently, and got the right answer (I already submitted the assignment, that's why I didn't put this in the homework subforum), but I had to introduce a new charge density term that doesn't seem to actually exist (but it's zero at T=0). The problem was...
18. Studying Need some advice -- Studying oscillations before differential equations?

Hello there, I need some advice here. I am currently studying intro physics together with calculus. I am currently on intro to oscillatory motion and waves (physics-wise) and parametric curves (calc/math-wise). I noticed that in the oscillatory motion section, I need differential equation...
19. Thermodynamics problem -- Pressure oscillations in a jar

I add a Figure with the problem and solution. I have difficulty with a solution to the given problem. Why ##F=-kx=Adp##, I do not understand minus sign because we are working with scalars not vectors. It is correct to say that ##\vec{F}=-kx\vec{i}##, but is not correct to say that ##F=-kx##. Can...
20. Finding the Oscillations of Pendulum A

First of all, I found the angular frequencies for both pendulum and breathing mode which are ##\omega_p = 4.95## ##\omega_b = 7.45## Then I found the normal mode coordinates equations: ##q_p(t) = A cos \omega_p t## ##q_b(t) = B cos \omega_b t## And the beating frequency (I'm not sure if I...
21. Automotive Factors affecting compression spring oscillations

Hi all, I'm studying the compression spring design issue that occurred in a machine design application. As illustrated below, spring is bouncing or oscillating after impact to a stopping surface (1 -> 2 -> 3 -> 4) and eventually stop after few bounces. Ideal case for this application is to...
22. Real and Complex representations of an oscillation equation

I've been trying to continue my education by self-teaching during quarantine (since I can't really go to college right now) with the MIT Opencourseware courses. I landed on one section that's got me stuck for a while which is the second part of this problem (I managed to finish the first part...
23. Attenuating floor oscillations with a cushion

I am trying to find any relation between the three parameters: Position of the floor wrt an inertial frame f Position of the cushion wrt floor c Position of the man wrt cushion m But this is really confusing, leaving me to a lot of unnecessary variables Do you know one smart way to start?
24. Springs and small oscillations

[Moved from technical forums, so no template] Summary:: A rod of length l and mass m, pivoted at one end, is held by a spring at its midpoint and a spring at its far end, both pulling in opposite directions. The springs have spring constant k, and at equilibrium their pull is perpendicular to...
25. Oscillations with fluid and pendulum

That's a good question, i am not sure how the water in liquid state will influence in the motion, but i imagine that can not exert any torque, i would say in the first case: Hollow sphere inertia moment: 2mr²/3 + ml² (2mr²/3 + ml²)θ'' = -mglθ (1) In the second case, otherwise, we will have...
26. B The nature of orthogonal oscillations (extending E&M)

Classical electromagnetic propagation evokes an electric field at right angles to a magnetic field. Does this complementary directionality have a simpler basis in QED? Are there any examples of an orthogonal component in other fundamental interactions? Thanks.
27. E

Exploring Soap Bubble Oscillations: A Comparison of Force and Energy Approaches

I have solved it with a force approach, but would like to know how to do it via an energy approach. For starters, here is the force approach. Consider a small, approximately circular, surface element of mass ##m## such that the angle from the centre to the edge of this element is ##\alpha##...

40. I Find the natural frequencies of small oscillations

Hi, Given a mechanic-problem, I've linearised a system of two differential equations, which the origin was Lagrange-equations. The system looks like this; $$5r \ddot{\theta} + r \ddot{\phi} + 4g \theta = 0´ \\ 3r \ddot{\theta} + 2r \ddot{\phi} + 3g \phi = 0$$  And I shall find the...
41. Finding the frequency of very small oscillations

So I'm working on this home assignment that has numerous segments. Firstly, I was asked to find the equilibrium distance between two particles in a potential well described by U(r). I did that by setting U'(r) = 0 and came out with r_equilibrium = 2^(1/6)*a. Now, I'm being asked to find the...
42. E

B Determining ansatz for forced oscillations in SHM

I've generally solved introductory second order differential equations the 'normal' way; that is, using the auxiliary equation, and if it is inhomogeneous looking at the complementary function as well, and so on. I know that sometimes it can be helpful to propose an ansatz and substitute it...
43. M

A Sessile drop fluid oscillations and frequencies

Hi PF! I'm looking at a sessile drop of water in ambient air. The drop is plucked lightly, inducing surface oscillations. The fundamental frequencies ##\lambda_i## can be computed from spectral theory, and output complex values, say ##\lambda_1 = 2+7i##. Now, I simulate the experiment via CFD...
44. I General solution of harmonic oscillations

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...
45. B Shifting of a Cosine Curve with negative phase angle values

Continuing on from the summary, the chapter has given a graphed example. We are shown a regular cosine wave with phase angle 0 and another with phase angle (-Pi/4) in order to illustrate that the second curve is shifted rightward to the regular cosine curve because of the negative value. Now, my...
46. How to find the number of oscillations a block goes through

This is the image provided with the problem, the values given include: d= 4.00 m, the mass of block one=0.200 kg, speed of block one=8.00 m/s, the period of oscillations for block two without friction=0.140 s, and the spring constant= 1208.5 N/m. I know how to solve the oscillations if block...
47. I Problem with the harmonic oscillator equation for small oscillations

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...
48. I Questions about bayronic acoustic oscillations

Summary: I have been trying to understand the abstract and introduction to the paper https://arxiv.org/pdf/astro-ph/0501171.pdf DETECTION OF THE BARYON ACOUSTIC PEAK IN THE LARGE-SCALE CORRELATION FUNCTION OF SDSS LUMINOUS RED GALAXIES. I made an effort to find in the paper the answers to...
49. A Preventing Oscillations w/ Coarse Calculation Increments?

I'm trying to solve the following set of equations across several discrete increments. These aren't the exact equations I'm using, but they're a simplified version with the same general structure...it's basically a set of equations describing a transfer rate along a fixed length, where "Z" is...
50. How to find the period of small oscillations given the potential?

I first found the equilibrium points taking the derivative of the potential. ##U'(x)=U_0 a\sin(ax)##, and the equilibrum is when the derivative is 0, so ##U_0 a\sin(ax)=0## so ##x=0## or ##x=\pi/a##. Taking the second derivative ##U''(x)=U_0a^2 \cos(ax)## I find that ##x=0## is a minimum point...