What is Natural frequency: Definition and 130 Discussions

Natural frequency, also known as eigenfrequency, is the frequency at which a system tends to oscillate in the absence of any driving or damping force.The motion pattern of a system oscillating at its natural frequency is called the normal mode (if all parts of the system move sinusoidally with that same frequency).
If the oscillating system is driven by an external force at the frequency at which the amplitude of its motion is greatest (close to a natural frequency of the system), this frequency is called resonant frequency.

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  1. D

    MHB Find Spring Constant \(k\) & Mass \(m\) for Natural Frequency

    The natural frequency of a spring-mass system is found to be 2Hz. When an additional mass of 1kg is added to the original mass \(m\), the natural frequency is reduced to 1Hz. Find the spring constant \(k\) and mass \(m\). Since the natural frequency is 2Hz, we have that \(\omega_n = 4\pi =...
  2. K

    Why is a vibration that reaches natural frequency so detrimental?

    Why are we not supposed to operate a machine on its natural frequency condition? I read max. energy transfer happens at this condition. What exactly does it mean? When we swing a pendulum it just oscillates on its natural frequency. Nothing goes wrong there. So what makes it different for a...
  3. A

    Calculating the natural frequency of a plate fixed at four corners

    How do I calculate the natural frequency of vibration of a rectangular plate of Al-6061, having dimensions 100 x 80 mm? The plate is fixed at four corners. Thank You
  4. S

    EE Topic: Relation between Temperature and Natural Frequency of an obj

    Hi guys, I am still new to this forum, so I hope I can learn many things from this forum :) I am currently looking for my IB EE topic about the relation between temperature and natural frequency on an object. I have been researching about this topic, however I don't find any specific...
  5. C

    Shaft - find natural frequency of horizontal shaft with bearings

    shaft -- find natural frequency of horizontal shaft with bearings how to find natural frequency of horizontal shaft with bearings at either sides, using (Ansys-classic). Please reply, Thank you.
  6. T

    Why is the natural frequency of a column at the buckling load?

    So apparently the natural frequency is zero for uniform column with axial load when P is equal to the critical buckling load. Could anyone please explain theoretically why this is the case.
  7. V

    How Does Coating a Cantilever Beam with Gold Affect Its Natural Frequency?

    A Cantilever beam of SiO2 of length 100μm, width 20μm and thickness of 5μm. How to calculate the resonant frequency? I know f=1/2∏√(k/m) where k=3EI/L^3 and mass = l*w*h *ρ (density) and I = w*t^3/12, but i don't get the desired answer. pl correct me. What changes are to be considered for...
  8. Manraj singh

    Natural Frequency: Why Does It Exist & Can It Be Changed?

    I have googled it but couldn't find a simple, easy to understand answer answer. Why does a body have a particular natural frequency. Can it be changed by any way?
  9. K

    Natural frequency from time domain and frequency domain plot

    Anyone have an idea to find a first and second natural frequency from time domain and frequency domain plot resulting from an accelerometer measuring the vibration in cantilever beam ? Thanks very much :)
  10. M

    Method of finding natural frequency

    This is a closed loop system. My teacher showed me that one of the methods to find the natural frequency of this system is by finding the frequency at phase -90 degrees. Why must it be -90 degrees? Please explain. From the phase graph, the frequency at -90 degrees is 32 [rad/s], so that's the...
  11. L

    Finding natural frequency of a steel flat

    is there a straight formula for finding one of the natural (preferably fundamental) frequency of a steel flat with dimension say, L=1000 mm, B=100 mm and Thickness T=10 mm ? The flat is fixed at both ends by bolts and two weights of equal magnitude are suspended at 1/4 and 3/4 (i.e. 250 mm and...
  12. F

    Computing Natural Frequency of a Torus System: 3D vs. 2D Added Mass

    Hi! I am trying to compute the natural frequency of a system and I also need to add the added mass term to my equation. The object I have is a torus and is basically in heaving motion. I found a good paper, which gives a formula for 3d added mass and 2d added mass. I would figure that I...
  13. J

    To which natural frequency does wavelength equal to L1

    Homework Statement The length L1, is not the wavelength of the fundamental frequency of the string. With the tension equal to F1, to which natural frequency does the wavelength equal to L1 correspond? Homework Equations I was reading online, and found that when a string vibrates at...
  14. T

    Resonance frequency and Natural frequency?

    Resonance frequency and Natural frequency?? Say there is an empty bottle of coke., and you know for sure that the bottle resonates most at 320hz. when the bottle resonates, the bottle will vibrate. the question is, 1.if the bottle also resoates at 318hz( bu not most), will the bottle...
  15. A

    Proof of natural frequency in RCL circuit

    I am just wondering what is the proof of the equation 2*pi*f = 1/√(LC)
  16. P

    Find the natural frequency of a spring

    Homework Statement Consider the spring-mass system shown. A dynamic load, P(t), is applied with a frequency of 300 rpm. The helical compression spring is made of a music wire. When installed, the spring force is to vary between 100 and 500 N while the spring height varies over a range of...
  17. P

    Calculate Natural frequency of a vibrator

    I have a construction of a vibrator (industrial use). I should be able to calculate the natural frequency, by means of Hooke's law. Since I have a physical device I already have a "real world" measurement of the Natural frequency. The problem is: How to calculate it? I have tried to do some...
  18. T

    Finding the natural frequency of a cylinder oscillating on a circular surface

    Homework Statement Here is the problem with my 3 attempts: 1. Alright, so the first attempt, I did not take into account the rotation of the cylinder ωc so I think it is wrong. But it seems to make sense because the whole cylinder rotates about O, so if I find that energy using parallel...
  19. J

    Natural frequency of oscillating electron

    Homework Statement a) Light of wavelength 510nm is emitted by an electron in an atom behaving as a lightly damped simple harmonic oscillator with a Q value of 3 x 107. Find the natural frequency of the system. b) Find the width of the resonance.Homework Equations The Attempt at a Solution...
  20. C

    The Nature of Natural Frequency

    I've been told that the natural frequency of an oscillator is the frequency an oscillator will oscillate at when left to itself. Is this referring to the frequency of an ideal oscillator subject to ONLY a restoring force. Because all REAL oscillators are subject to damping and, when left to...
  21. T

    The derivation of damped frequency and natural frequency formula

    Can someone derive for me the equation ωd=ωnsqrt(1-ζ2) Thanks
  22. C

    Natural frequency, damping ratio and steady state amplitude help needed

    (1) A mass of 3.0 kg is suspended from a vertical spring and produces a static deflection of 60 mm. The system is also subjected to viscous damping of 36 N s/m. Calculate the value of the: (a) natural frequency i. In Hz ii. And rad/s (b) damping ratio...
  23. D

    Resonant Frequency & Natural Frequency?

    Hello guys! Is it possible to convert a natural frequency to resonant frequency with maybe some kind of formula? I was given a transfer function and I was asked to draw a root locus plot and determine the resonant frequency. I know how to get the damping ratio and natural frequency and the value...
  24. Y

    Natural Frequency of Solid Spheres

    Dear Physics Forum community, I am posting here as a last resort, so any guidance/references would be much appreciated. As a small part of my project, I need to calculate the natural frequency of metallic solid spheres. All I have been able to find on the web is the Schummann Resonance...
  25. A

    Q of tuning fork; resonant and natural frequency

    Homework Statement A musicians tuning fork rings at A above middle C, 440Hz. A sound meter level meter indicates the sound intensity decreases by a factor of 5 in 4 seconds. What is Q of the tuning fork? Homework Equations Q=\frac{\omega}{2\beta}...
  26. H

    Natural Frequency in Finite Element Method

    Hi all, A fixed-free bar has a single natural frequency. When we discretize such a bar in the finite element method, then the natural frequencies are the eigenvalues and an nχn matrix where n is the number of the degree of freedom which is usually large. Thus we obtain up to n natural...
  27. F

    Difference between forcing frequency and natural frequency

    If you force a one-dimensional discrete lattice to vibrate at the mass at the origin sinusoidally with forcing frequency w0, what will the frequency of vibrations be for the lattice points, NOT at the origin ? Will it be the natural frequency ? Or will it be close to the forcing frequency near...
  28. G

    Help w/ using Blevins formula for natural frequency of a cylinder

    I came across this formula by Blevins for calculating the natural frequency of a hollow cylinder and was hoping that someone could answer a question I have for calculating the mass per unit length (m). Here's the formula: f = A/(2*pi*L^2)*sqrt(E*I/m) A= 9.87 for first mode I = Area Moment of...
  29. M

    What Is Natural Frequency & How Does It Affect Objects?

    I am having trouble understanding resonance. But before that I need to understand natural frequency of an object. I saw similar questions posted in the forum, but I don't understand the answers fully. So what exactly is a natural frequency? One answer which I have read says "Nearly all...
  30. G

    Troubleshooting Tube Bending Natural Frequency Equation

    I found this equation for predicting the bending natural frequency of a tube but am having trouble working it out. I was hoping that someone might be willing to steer me in the right direction. First the equation and the info provided on the website: w = (B*l)2 * SQRT (E*I/(rho*l4)) w -...
  31. T

    Question about Natural Frequency and Resonance

    So, I was reading a book on Nikola Tesla the other day, and it said that he said that he could theoretically split the Earth in two with resonance. If I had a variable frequency oscillator, and I knew the natural frequency of an object, obviously I could create a standing wave. But, could I, as...
  32. L

    Natural frequency of aircrafts

    Hi How can you find the natural frequency of an aircraft? It would be of great help if anybody can give me an idea of how to go about the problem.
  33. S

    Can damping affect the prediction of resonance using natural frequency?

    Can I say that the natural frequency is the frequency of a system vibrating without effect of forces and including all parameters of damping that could occur on the system? Resonance would occur when the forcing frequency equals the antural frequency.
  34. H

    Finding the natural frequency of a steel beam

    Homework Statement I am trying to calculate the natural frequency of a steel beam. Homework Equations I=1/12*W*T^3 Volume= T*W*L M0=V*ρ K=(3EI/L^3) Meff=(33/140)*M0+Mend ωn=√(k/Meff) The Attempt at a Solution This should be a simple plug and chug problem but I can't see what...
  35. D

    Natural frequency of large degree of freedom system

    I have a spring-mass system with 200 masses and 199 springs. All masses are 100 tonnes and stiffness 20 MN. The boundary conditions are fixed-free. I have constructed a lumped mass matrix and stiffness matrix and calculated the lowest natural frequency. Including the boundary conditions I...
  36. S

    Natural Frequency and mode shapes

    Hi I am using Ansys to find the natural frequency of a structure but this has meant that my understanding of vibrations has become unstuck. When I last studied natural frequencies, it was under free vibration. I formed the impression that one structure can have only one natural frequency...
  37. K

    What actually is natural frequency?

    when we talk about the phenomenon of resonance, we use the term 'natural frequency'. What actually is natural frequency of an object?...what is meant by matching of natural and applied frequency and why does it produce vibration with maximum amplitude?
  38. M

    Natural Frequency of a Spring System

    A mass m is confined to move in a channel in the x-direction and is connected to four identical springs with spring constant k, which are oriented at angles \phi = 45° as shown, if the system is in static equilibrium. a) Ignoring friction, determine the natural frequency of vibration of the...
  39. S

    Time period and natural frequency

    A fundamnetal question here; IS it that the terminologies natural time period and frequency are used only for simple harmonic motions and not for motions which are periodic/sinusoidal like an SHM?
  40. Y

    Natural Frequency Question SI Units

    i have a basic question about the natural frequency of a system. for a mass (M), spring (k constant) undamped system the natural frequerncy is: w_n=sqrt(k/M) the units of w_n according to a lot of resources i found on the internet & textbooks are [rad/sec], my question is why? if i use...
  41. O

    Formula for Natural Frequency of Cantilever Beam

    I found two different versions of equations to find natural frequency of a cantilever beam. I am not sure which one is right. I would appreciate if someone could make things a bit clear here F1= k^2*sqrt(E*I/(mpl*L^4))/(2*pi) where k=1.875 for first natural freq and I= b*d^3/12; OR is...
  42. U

    How do natural frequency sensors measure solid and vessel frequency?

    Hi all ! i want to know some of the devices that measure natural frequency of solids/vessels, etc ! with regards! take care !
  43. J

    Cantilever Beam, Tapered in breadth, uniform thickness, natural frequency

    Hey there I need to find the natural frequency of a Cantilever Beam. The beam is tapered in breadth, but has a uniform thickness. So basically the end goal is an equation for f as a function of the angle of the side cut. Clamped at one end L=constant B=changes though the length of the...
  44. K

    How can mass distribution affect the derivation of a natural frequency equation?

    Hi I want to derive a natural frequency equation for a system. I saw this question in a book. so they gave us an equation frequency = (1/2pi) * ( sqrt( k/m1+m2+m3/3+4m4+Ic/r2) ) Ic = Moment of inertia of pulley about rotational axis r = effective radius of pulley k = spring constant now the...
  45. S

    Calculating the natural frequency of a piping system

    I'm calculating the natural frequency of a piping system that is spanning between two points, the formula is the square route of various terms, including the effective axial force in the piping. This is taken from a design code, see below: f = C * SQRT[(E.I/M.L^4)(1+Seff/Pcr+C.(d/D)^2] C =...
  46. S

    Sloshing vertical natural frequency

    Hi, I need to estimate the sloshing natural frequency, in the three axis of a rectuangular tank, not fully filled of liquid. I need this for understading how changes the vehicle dynamics in some trucks. I have found a linear formula for the horizontal direction, but I have found nothing...
  47. K

    Natural frequency of a wind turbine

    how do we find the natural frequency of a tower of a wind turbine if, say, the tower is circular hollow cross sectional shape (its not tapered or anything, just cylindrical all the way up). I think i know how to find it when we're ignoring its weight, but what is it when weretaking into account...
  48. B

    The natural frequency of a mass-spring system.

    Homework Statement A certain spring elongates 9mm when it is suspended vertically and a block of mass M is hung on it. The natural frequency of this mass-spring system is: a)0.014 b) 5.3Hz c) 31.8Hz d) 181.7 e) need to know M x=9mm mass=M Homework Equations I don't know any...
  49. H

    Calculating Undamped Natural Frequency of a Cantilever Beam

    Homework Statement Hi. I'm trying to work out the undamped natural frequency of a cantilever beam. The setup of the system is shown in the image below. http://www.flickr.com/photos/56901717@N03/5249378659/ Data:(all lengths measured from the hinge on the left of the beam) Beam...
  50. M

    Natural frequency of beam exposed to sinusoidal force

    Hello, I am taking a vibrations course and we are currently talking about using PDEs to find responses of beams. In the book, there is an equation to find the natural frequencies of a simply supported beam under an axial load: omega = (pi^2/l^2)*sqrt(EI/roA)*sqrt(n^4 + (n^2*P*l^2)/(pi^2*EI))...
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