What is Sinusoidal: Definition and 229 Discussions

A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation. A sine wave is a continuous wave. It is named after the function sine, of which it is the graph. It occurs often in both pure and applied mathematics, as well as physics, engineering, signal processing and many other fields. Its most basic form as a function of time (t) is:

where:

A, amplitude, the peak deviation of the function from zero.
f, ordinary frequency, the number of oscillations (cycles) that occur each second of time.
ω = 2πf, angular frequency, the rate of change of the function argument in units of radians per second




φ


{\displaystyle \varphi }
, phase, specifies (in radians) where in its cycle the oscillation is at t = 0. When



φ


{\displaystyle \varphi }
is non-zero, the entire waveform appears to be shifted in time by the amount φ/ω seconds. A negative value represents a delay, and a positive value represents an advance.
The sine wave is important in physics because it retains its wave shape when added to another sine wave of the same frequency and arbitrary phase and magnitude. It is the only periodic waveform that has this property. This property leads to its importance in Fourier analysis and makes it acoustically unique.

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  1. K

    Power of discrete sinusoidal signal?

    I am a little confused of the last step. We can set an upper boundary for any arbitrary large number M, so it seems ok. do you agree on the last statement?
  2. Domenico94

    Response of a system (Control theory)

    Hi everyone. I'm studying for the exam of control theory, and now I'm having an hard time with the response of a system, in particular when we have oscillations. Suppose you have a system, with a transfer function, say, G(S), in the form: G(S) = 1 -------------------...
  3. KingDaniel

    Systems Modeling - Sinusoidal Inputs

    Homework Statement Finding the complete response (steady-state and transient) is a long and laborious task. My lecturer's notes read (since at our stage of the course, we're mostly interested in the steady-state part of the solution and not so much the transient) : "The simple method for...
  4. KingDaniel

    Systems Modelling Question - Sinusoidal inputs (Important)

    Homework Statement Hi, When finding the steady-state response to a sinusoidal input, since "s" is a complex number, (a + jw), why do we substitute "s" with only the imaginary part (jw) in the transfer function, G(s) , to get G(jw), rather than substituting the whole complex number to get G(a +...
  5. R

    Do All EM Waves Have a Sinusoidal Shape?

    I understand that sinusoidal EM waves result from charged particles in harmonic motion, e.g., up and down an antenna. But what if the charge is undergoing some more complicated periodic motion? Wouldn't the EM waves be non-sinusoidal? I saw in a textbook a hypothetical EM wave with infinite wave...
  6. J

    Integrating acceleration sin wave

    This is a really basic calc/physics question.If acceleration is defined as Acc= Asin(w*t), and I integrate this to get velocity, I get Vel=(-A/w)*cos(w*t)+C. If the velocity at t=0 is 0, then C=A/w. If I then integrate the velocity to get the displacement, I get...
  7. A

    Velocity Derivative of a Sinusoidal Wave (Counter-Intuitive)

    What's the matter: So, I think I have some skills when it comes to differentiation after taking calculus 2 last semester, but when it starts to intertwine with physics, and interpreting physical phenomenon through equations, It appears I could use some help. Anyway, the problem that I got hung...
  8. O

    Decay of sinusoidal velocity wave (kolmogorov flow)

    Homework Statement Find the velocity field u(x,t) Homework Equations \rho = constant u(0,t)=0 u(0,L)=0 \frac{\partial u}{\partial t} = \nu \frac{\partial ^{2}u}{\partial x^{2}} u(x,0)=U_{o}[sin(\frac{3\pi x}{L})+0.7sin(\frac{9\pi x}{L})] The Attempt at a Solution I have absolutely no idea...
  9. Puma

    Sinusoidal path of light video

    Can you explain the sort of sinusoidal path here: http://i.imgur.com/vN7PJCu.gif
  10. A

    Finding the wavelength on a sinusoidal wave on a string

    Homework Statement Hi, this is a problem regarding mathematical descriptions of waves. I've attached an imagine of the picture but I'll also type out the problem for clarity. "A sinusoidal wave is propagating along a stretched string that lies on the x-axis. The distplacement of the string as a...
  11. S

    Finding Function Values on a Graph: f(30) and f(-14) Explained

    1. Homework Statement A graph of y=f(x) is shown. Find the following function values and justify your answers. f(30)= f(-14)= Homework EquationsThe Attempt at a Solution I know the graph is periodic, I know it's max and min, and I know it's amplitude because of that. But I don't know what...
  12. J

    Steady State Sinusoidal using Nodal Analysis

    Homework Statement [/B] The photo included provides the problem but the professor stated that the right side source is supposed to be 100t and not 80t. The problem wasn't printed correctly in the book so I assume the solution wasn't either. The solution via the book is v1=2.56cos(100t+139.2°)...
  13. ThisVelvetGlove

    Sinusoidal alternating current/Homework

    Hello everyone thanks for giving me your support, sorry if i post in the wrong section. 1. Homework Statement What the problem asks for: In the picture we can see the graph of sinusoidal i1=i1(t) and i2=i2(t) It asks for: ν(as i read, it said only one so that's how i went beyond on...
  14. E

    Sinusoidal fit with some points fixed

    I'm doing some image processing of some tidal lines that I'm trying to digitize from photographs using Matlab. The digitization is heavily dependent on the indexing of the image of x-values (time) and y-values (water level). After some initial processing based on pixel contrast, line continuity...
  15. K

    How is sinusoidal current generated?

    I'm delving into AC as well as attempting to understand the various wave forms used in electrical engineering, and I am curious how engineers are able to generate current which alternates in a sinusoidal manner. What specific phenomena allows us to achieve this? Is it a special circuit, or does...
  16. B

    MHB Fitting a function to a sinusoidal curve

    Hi Folks, I have a curve that varies sinusoidally calculated from a numerical program as attached "Trace.png". I would like to fit this amplitude modulation expression to it. f(t)=A[1+B \cos(\omega_1 t+ \phi)] \cos(\omega_2 t+ \theta) I managed to adjust the parameters manually to get a very...
  17. R

    Stress at crack tip of a 2D cantilever beam under sinusoidal excitation

    I need some information urgently. I am working on crack of a 2-D cantilever beam. One side of the beam is fixed. I am applying a sinusoidal time varying load on other end in Y-direction.Beam length and width are 100cm and 10cm respectively. crack is 05 cm in y-direction. I have attached data and...
  18. R

    Sinusoidal electromagnetic wave help

    Homework Statement A sinusoidal electromagnetic wave from a radio station passes perpendicularly through an open window that has area of 0.700m2 . At the window, the electric field of the wave has an rms value 2.30×10−2V/m . How much energy does this wave carry through the window during a...
  19. B

    Why are standing waves on a guitar string sinusoidal?

    Ok I understand the idea that a standing wave can be represented as the sum of two traveling waves going in opposite directions with same stuff but what I don't understand is why the waves on a guitar string are sinusoidal. I mean I know looking at them, they look sinusoidal but could they be...
  20. J

    Waves and optics pertaining to sinusoidal waves

    Homework Statement https://us-mg5.mail.yahoo.com/neo/launch?.rand=768lpb97vo87e#4636076903 The picture displayed shows three graphs and in each problem the objective is to find the phase constant. I'm having an issue attempting any form of strategy to solve these problems. Any help would be...
  21. J

    Walking sinusoidal as you follow a RF Standing Wave?

    A friend who was in Civil Air Patrol once told me he was using some RF Locator equipment and was "homing in" on a target. His walking path to the target was sinusoidal because of the wavelength of the frequency used. He said he was literally walking the wave.... Standing wave, I assume? Or...
  22. A

    Sinusoidal Current of .5 Amps (rms) & 5 kHz

    This is just a quick question: A problem I'm working on says "a sinusoidal current of .5 amps (rms) and 5 kHz." Later, in the problem solution, I(t) is written as .5 \sqrt{2} \cos{(10^4 \pi t)}. I think I'm simply misunderstanding something about the construction of a current function when...
  23. Serious Max

    Word problem involving sinusoidal model

    Homework Statement Homework Equations y=30\sin(\dfrac{2\pi}{20}t)+270 General principal solutions: t=\left(\dfrac{\arcsin(\dfrac{1}{3}) 20}{2\pi}\right)+20k, k\in \mathbb{Z} t=1.08173+20kGeneral symmetry solutions: t=\left(-\dfrac{(\arcsin(\dfrac{1}{3})-\pi)20}{2\pi}\right)+20k, k\in...
  24. P

    Sinusoidal Pressure Wave: Questions & Answers

    Homework Statement Consider a sinusoidal pressure wave in a gas with a fixed displacement amplitude of 1cm. The gas has a density of 2 kg m-3 and the wave travels at a velocity of 10 m s-1. a) What is the bulk modulus of the gas? [3]...
  25. E

    MHB Sketch the sinusoidal graphs that satisfy the properties

    12a) Sketch the sinusoidal graphs that satisfy the properties below: Period: 4 Amplitude: 3 Equation of the Axis: y = 5 Number of Cycles: 2 So, I know how to graph sinusoidal functions, but I can't figure out the max and min that would satisfy both the equation of the axis and the amplitude listed.
  26. R

    Can a sinusoidal EM wave exist in nature?

    I saw an example of a hypothetical EM wave that had constant E and B fields. Is that possible? How would it be produced? And wouldn't such a wave have an infinite wavelength?
  27. R

    MHB How do I find A,B,C, and D in a sinusoidal function?

    I really need someone to break it down for me. I think I understand A and D, but I am confused on B and C. I have some example problems. But first, the equation my pre-calculus teacher has given us is y=Asin(2π/B(θ-C))+D. But I am still having a lot of trouble. Find amplitude, period, a phase...
  28. I

    Max transverse speed on a sinusoidal wave

    Given the below equation of a sinusoidal wave, find the maximum transverse speed of a point on the string. y(x,t) = .00325m * sin(70x -3t) I am brand new to waves and trying to figure out what this question exactly means. The way I see it is that it might be at a max speed when 70x-3t =...
  29. J

    Sinusoidal and exponential series

    If is possible to expess periodic functions as a serie of sinusoids, so is possible to express periodic functions with exponential variation through of a serie of sinusoids multiplied by a serie of exponentials? Also, somebody already thought in the ideia of express any function how a serie of...
  30. V

    Adding sinusoidal functions using phasors

    Homework Statement Homework Equations The Attempt at a Solution $$3cos(20t+10°)-5cos(20t-30°)\\ =3\angle 10°-5\angle -30°\\ =-1.376+3.0209j\\ =3.32\angle -65.51°$$ In the last step, the textbook actually got ##3.32\angle 114.49°##. I checked both answers and it seems that the textbook's...
  31. sbstratos79

    Preference of Angular frequency over frequency for sinusoidal graphs

    Quote from 'The Physics of Vibrations and Waves by H.J.Pain': "However when we solve the equation of motion we shall find that the behaviour of x with time has a sinusoidal or cosinusoidal dependence, and it will prove more appropriate to consider not \nu, but the angular frequency \omega =...
  32. A

    Fourier transform of sinusoidal functions

    Homework Statement Homework Equations sinc(x) = \frac{sin(x)}{x} The Attempt at a Solution bit unsure how to get started?? i know transform of rectangular pulse pτ(t)=τ*sinc(τω/2∏) also that sin(ωt)= ejωt-e-jωt / (2) I could also probably sketch sinc(t/2∏), if that helps.
  33. B

    Why Use Sinusoidal Signals?

    It appears that sinusoidal signals are very useful in signal processing, communications, and information theory. I am curious to know very why. I understand that information can be transmitted via a sine wave, from the principle that sine waves of different frequencies are orthogonal. But use...
  34. L

    Area under v vs t sinusoidal trace

    if I have a sinusoidal trace on an oscilloscope (v vs t) and I wanted to find the area under the wave form squared graph I could integrate the sqaured waveform with respect to t. but since i don't have the integration facility... is it fair to say that the area under the graph is proprtional...
  35. C

    Convert between sinusoidal / phasor, find average power, impedance

    Homework Statement http://imageshack.us/a/img834/8450/4y0t.jpg Given V(s)t = 100cos100t volts, find the average power supplied by the source and the current i2t in the network. Homework Equations V = IR V = IZ Z = V/I inductor impedance: ZL = ωLj capacitor impedance: Zc =...
  36. D

    Find the sinusoidal signal at specific frequency

    Homework Statement For a phasor V(x) = 8 + 4j find the sinusoidal signal that it represents if the frequency is 50 Hz? Homework Equations The Attempt at a Solution sqrt(64+16)=8.944sin(50t) so clearly this is not correct?
  37. U

    Capacitor with sinusoidal voltage placed near a plate

    Homework Statement An electrode with a varying voltage V = V0 + VACejωt is placed near a plate. The current output from the electrode is then measured. We want to find the relation between the current output and the amplitude of vibration. We can assume VAC is small relative to V0...
  38. W

    Two Transverse Sinusoidal waves combine in a medium

    Homework Statement Two Transverse Sinusoidal waves combine in a medium are described by the wave functions: y1 = 3sin∏(x + 0.600t) y2 = 3sin∏(x - 0.600t) what is y1 + y2? Homework Equations the hint is that I am supposed to use: sin(α + β) = sin(α)cos(β) + cos(α)sin(β) The Attempt at a...
  39. D

    How do Sinusoidal output comes out in the Wein-Bridge Oscillator

    This question was asked to me in a VIVA. [b]What examiner asked. [b] How do Sinusoidal output comes out in the Wein-Bridge Oscillator. ... I tried to solve the problem using the control system. That is, by deriving the transfer function of the...
  40. R

    Sinusoidal function. Top percentage of values.

    Homework Statement For a sinusoidal function, how do you determine the highest value exceeded 10% of the time? The pink line in the attached pic indicates that value. Just wondering how you actually determine the value for a periodic function? Homework Equations The Attempt...
  41. MarkFL

    MHB Sarah's question at Yahoo Answers regarding a sinusoidal function

    Here is the question: Here is a link to the question: One of the largest ferris wheel ever built is in the british airways london eye which was completed in 2000. T? - Yahoo! Answers I have posted a link there to this topic so the OP can find my response.
  42. P

    Find derivative of complex sinusoidal function

    Homework Statement Find derivative of: h(x) = 3e^{sin(x+2)} Homework Equations chain rule of derivatives, product rule(?) The Attempt at a Solution I'm quite sure I'm doing this wrong. Because the exponent is a product, for the derivative of the exponent I would have to use the...
  43. N

    Simplify Sinusoidal Function 2sin(wot+45)+cis(wot) to Acos(wot)

    2sin(wot+45)+cis(wot) to Acos(wot) i convert it 2e^-j45 = √2/2 - j√2/2 1e^j0 = 1 - j0 adding these up i get (√2/2 + 1) -j(√2/2) 1.707 - j.707 magnitude = √1.707²+.707² = 1.85 angle = tan^-1(.707/1.707) = 22.5 so i get 1.85cos(wot +22.5) while the book has the answer...
  44. M

    MHB The Unit Circle, the Sinusoidal Curve, and the Slinky....

    I seem to recall when taking college Trigonometry my professor saying that the unit circle and sinusoidal curves were basically a mathematical represention of a slinky in that the unit circle was the view of a slinky head on, so that what you saw in the two dimensional sense was a circle, and...
  45. J

    Infinite Well with Sinusoidal Potential

    Homework Statement Assume a potential of the form V(x)=V_{0}sin({\frac{\pi x}{L}}) with 0<x<L and V(x)=\infty outside this range. Assume \psi = \sum a_{j} \phi_{j}(x), where \phi_{j}(x) are solutions for the infinite square well. Construct the ground state wavefunction using at least 10...
  46. C

    A formula for sinusoidal graphs of this form?

    Hey all I am trying to generate a graph of a sinusoidally oscillation against time. However, the time itself is passing sinusodally, i.e time flows faster at some points and slower at others. I'm doing this as I need test data for a program I've written to decode real world data I'm...
  47. T

    Why are sinh and cosh named after sinusoidal functions?

    We learned about those functions last semester but they seemed to have to do nothing with sine and cosine? They were defined using the exponential function.
  48. D

    Sinusoidal sources and complex power

    When calculating power in a given circuit, why is the complex conjugate of the current used to compute power?
  49. M

    Simple sinusoidal wave can't convey information?

    Hello, Here http://www.mathpages.com/home/kmath210/kmath210.htm it is written that "...in order to actually convey information, a signal cannot be a simple periodic wave...". I've met this statement in several other places too, this one is just for reference. What does that mean that a simple...
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