What is Harmonic motion: Definition and 1000 Discussions

In mechanics and physics, simple harmonic motion (sometimes abbreviated SHM) is a special type of periodic motion where the restoring force on the moving object is directly proportional to the object's displacement magnitude and acts towards the object's equilibrium position. It results in an oscillation which, if uninhibited by friction or any other dissipation of energy, continues indefinitely.
Simple harmonic motion can serve as a mathematical model for a variety of motions, but is typified by the oscillation of a mass on a spring when it is subject to the linear elastic restoring force given by Hooke's law. The motion is sinusoidal in time and demonstrates a single resonant frequency. Other phenomena can be modeled by simple harmonic motion, including the motion of a simple pendulum, although for it to be an accurate model, the net force on the object at the end of the pendulum must be proportional to the displacement (and even so, it is only a good approximation when the angle of the swing is small; see small-angle approximation). Simple harmonic motion can also be used to model molecular vibration as well.
Simple harmonic motion provides a basis for the characterization of more complicated periodic motion through the techniques of Fourier analysis.

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  1. N

    Bead on a Wire and Harmonic Motion

    A wire could be shaped like a sinusoidal function and then we could say the bead moves harmonically. The shape of the wire, so that bead occilates around X = 0. Y = -50*cos(10X) If we ignore friction and give it a small dispalcement then it is possible to find angular frequency...
  2. M

    Harmonic Motion and Springs Question

    I'm trying to derive the formula for the period T as a function of the mass of the object. Here is my attempt. Note that I cheated and passed the section I had trouble with, without fully understanding it. http://www.filehive.com/files/0722/image.jpg Much of this is quite straightforward for...
  3. A

    Calculating Speed of Simple Harmonic Motion with Initial Displacement

    Please help with the following problem: A 0.1 kg block rests on a level surface and is attached to a horizontally aligned spring with a spring constant of 32 N/m. The block is initially displaced 4 cm from the equilibrium position and then released to set up a simple harmonic motion. A...
  4. Amith2006

    Weakly Damped Harmonic Oscillator: Phase Difference

    Sir, A weakly damped harmonic oscillator is executing resonant oscillations. What is the phase difference between the oscillator and the external periodic force?
  5. C

    Pendulum Harmonic Motion Help Needed Asap ( work is shown)

    A bungee jumper with mass 66.0 kg jumps from a high bridge. After reaching his lowest point, he oscillates up and down, hitting a low point eight more times in 35.5 s. He finally comes to rest 28.0 m below the level of the bridge. Calculate the spring stiffness constant of the bungee cord...
  6. B

    Damped harmonic motion sinusoid equation

    what is the equation? i have something written down in my notes but i really don't get it... x=A(e^-kt)(cos omega t) first of all, how is the amplitude calculated if it decreases over time?? is it averaged? what is e? second of all, to calculate k, you need hooke's law and you need...
  7. C

    Harmonic Motion/ max Velocity

    An object with mass 3.5 kg is attached to a spring with spring stiffness constant k = 300 N/m and is executing simple harmonic motion. When the object is 0.020 m from its equilibrium position, it is moving with a speed of 0.55 m/s. b) Calculate the maximum velocity attained by the object...
  8. D

    Damped Simple Harmonic Motion problem

    I'm having trouble with this problem.The suspension system of a 2100 kg automobile "sags" 7.2 cm when the chassis is placed on it. Also, the oscillation amplitude decreases by 35% each cycle. Estimate the values of (a) the spring constant k and (b) the damping constant b for the spring and shock...
  9. S

    Simple Harmonic Motion and Damping

    Textbook Question: Which one of the following terms is used to describe a system in which the degree of damping is just enough to stop the system from oscillating? a) Slightly damped b) Underdamped c) Critically damped d) Overdamped e) Resonance Textbook says that the smallest...
  10. M

    Simple Harmonic Motion of a plank of mass

    I don't understand the solution to the following problem: A horizontal plank of mass m and length L is pivoted at one end. The plank's other end is supported by a spring of force constant k. The moment of inertia of the plank about the pivot is (1/3)m(L^2). The plank is displaced by a small...
  11. C

    Simple Harmonic Motion of a block

    A 0.50 kg block sits on top of a 5.00-kg block that rests on the floor. The larger block is attached to a horizontal spring that has a force constant of 15.0 N/m. It is displaced and undergoes simple harmonic motion. What is the largest possible amplitude the 5.00-kg mass can have for the...
  12. E

    Calculating Frequency of Oscillation for Different Masses on a Spring

    "A 0.25kg mass on a vertical spring oscillates with a frequency of 1.0 Hz. Suppose a 0.50kg mass were instead suspended from the same spring. What would be the frequency of oscillation in this case?" This is what I did: \frac{f_{1}}{f_{2}} = \frac...
  13. M

    Is the Motion of Particle P Simple Harmonic?

    A particle P of mass 0.2kg is attatched by an elastic spring of modulus 15N and natural length 1m to a point A of the smooth horizontal surface on which P rests. P receives an impulse of magnitude 0.5Ns in the direction AP. Show that while the string is taught, the motion of P is simple harmonic...
  14. K

    Simple Harmonic Motion and frequency of a spring

    I have one question here,I fail to understood what is Q of the system,is anybody has an ideal on this? An object of mass 2 kg hangs from spring of negligible mass. The spring is extended by 2.5 cm when the object is attached. The top end of the spring is oscillated up and down in SHM with...
  15. M

    Simple Harmonic Motion - Alevel M3

    This is probably a really easy question. But alas the answer has eluded me thus far. Anyway, here is the question:- Points O, A and B lie in that order on a straight line. A particle P is moving on the line with S.H.M period of 4s, amplitude 0.5m and centre O. OA is 0.1m and OB is 0.3m. When...
  16. S

    Simple harmonic motion and maximum speed

    I got a question, what is the maximum speed of an object undergoing SHM? and what is the max. acceleration. I am not sure how to solve this without any data given. I know that velocity v=-Awsinwt. and accleration is a=Awcoswt. So how am I to find the max speed and max acceleration?. Pls help.
  17. K

    Calculating Initial Velocity with Spring Constant and Mass: Homework Problems

    These questions on my homework are so hard. anyone get them? "The Spring constant for the spring in a special cannon is 1800N/m. In cocking the cannon, the spring is compressed .55m. What is the initial speed of a 7.0 kg cannonball at rest on the free end of the spring when it is released?"...
  18. E

    Solving Simple Harmonic Motion: Finding First Times for X=0 and V=0

    I am trying to solve the part c of the question. I know the initial condidtions of the motion which are Xo=3 and Vo=50 my W=10 , B1=3 B2=5 and my equation is x(t)=3cos(10t)+5sin(10t), the question is at which first times x=0 and x(2dot)=V=0, Now, when I plot the equation on excel, I...
  19. G

    Simple harmonic motion of clock

    let us consider a bob suspended by means of a thread from a fixed point (wrt ground and i m considering ground to be an inertial frame in this problem ) . What will be the time period of small oscillations of this pandulum as seen by a man accelerating with an acceleration a along the horizontal...
  20. N

    How Accurate Are These Calculations for Simple Harmonic Motion?

    A block of mass 0.5kg moving on a horizontal frictionless surface at 2.0 m/s collides with and sticks to a massless pan attached to the end of a horizontal ideal spring whose spring constan is 32 N/m. a) Determine the function for x(t), the displacement from equilibrium position as a function...
  21. N

    Physics - Simple Harmonic Motion

    A block of mass 0.5kg moving on a horizontal frictionless surface at 2.0 m/s collides with and sticks to a massless pan attached to the end of a horizontal ideal spring whose spring constan is 32 N/m. a) Determine the function for x(t), the displacement from equilibrium position as a function...
  22. D

    Simple harmonic motion summary

    What is mean by harmonics in SHM?
  23. A

    Calculating Maximum Speed of a Child on a Swing | Simple Harmonic Motion

    I don't find this topic too difficult but I am really stuggling on a question (im sure its really simple though) A child on a swing rises throught a height of 0.5m. Ignoring resistive energy losses, calculate the maximum speed of the child (the child doesn't increase/decrease swing height and...
  24. K

    Simple Harmonic Motion oscillations

    A 0.49 kg mass attached to a spring (k = 19.8 N m-1) is performing SHM on a smooth horizontal surface. Calculate the periodic time of these oscillations, in s. what equation links with T=2pi/w to give T or how do i use a=-ky/m. thanks in advance
  25. V

    Friction and harmonic motion

    Two blocks (m = 0.468 kg and M = 2.41 kg) and a spring (k = 24.1 N/m) are arranged on a horizontal, frictionless surface. Block m is situated on top of block M. (Spring attached to block M) The coefficient of static friction between the two blocks is 0.873. What is the maximum possible...
  26. S

    Simple Harmonic Motion - seemingly easy yet

    The function x = (2.0 m) cos[(2pi rad/s)t + pi/2 rad] gives the simple harmonic motion of a body. Find the following values at t = 4.0 s. (a) the displacement: ____m Correct me if I am wrong, but to get x all I have to do is just plug 4.0 s in for t in that equation mentioned above right? I...
  27. N

    Simple Harmonic Motion acceleration problem

    This is a problem right out of the book. My professor worked it out in class but now that I look over it I'm not sure why he chose the method he did. This is the problem exactly as it is stated in the book: From this I was able to derive several other components that will be very helpful for...
  28. R

    Simple Harmonic Motion formula

    Hi. I've got a problem here about Simple Harmonic Motion. There is "formula" in our physics coursebook for the distance traveled by an object : s=4AN=4At/T s-distance travelled A-amplitude N-number of cycles t-time T-period Is it true for every case or just for N=1, 2 , 3 ? I guess...
  29. B

    Some one me with part B. (Simple Harmonic Motion)

    Some one please help me with part B. (Simple Harmonic Motion) Online waiting! Simple Harmonic Motion A block of mass M = 10 kg is hanging, at rest, from a spring with a force constant of 250 N/m. There is also a very small penny sitting on top of the block. (Note: The penny is not stuck to the...
  30. B

    Some one me with part B. (Simple Harmonic Motion)

    Simple Harmonic Motion A block of mass M = 10 kg is hanging, at rest, from a spring with a force constant of 250 N/m. There is also a very small penny sitting on top of the block. (Note: The penny is not stuck to the block and can leave the surface of the block.) The block is now pulled down...
  31. K

    Simple Harmonic Motion Problem

    A computer to be used in a satellite must be able to withstand accelerations of up to 32 times the acceleration due to gravity. In a test to see if it meets this specification, the computer is bolted to a frame that is vibrated back and forth in simple harmonic motion at a frequency of 11.4 Hz...
  32. D

    What is the relationship between simple harmonic motion and amplitude?

    Hi, I'm having trouble with this problem because I don't know how to deal with all these unknowns: 4. A block attached to a spring with unknown spring constant oscillates with a period of 2.0 s. What is the period if : a. The mass is doubled? b. The mass is halved...
  33. I

    Simple harmonic motion problems

    1. three 10,000kg ore cars are held at rest on a 30degree incline on a mine railway using a cable that is parrallel to the incline. The cable is observed to strech 15cm just before the coupling between to lower two cards creaks, detaching the lowest car. Assuming the cable obeys Hook's Law...
  34. D

    Please help with this Harmonic Motion

    Please help with this! Harmonic Motion Two masses m1=100 g and m2=100 g slide freely in a horizontal frictionless track and are connected by a spring whose force constant is k=.5 N/m. Find the frequency of oscillatory motion for this system. I know omega = sqrt (k/m), but I have two masses...
  35. D

    Calculating Frequency of Harmonic Motion for Two Masses Connected by a Spring

    Two masses m1=100g and m2=200g slide freely in a horizontal frictionless track and are connected by a spring whoser force constant is k=.5 N/m. Find the frequency of oscillatory motion for this system. Could someone give me a hint/help me get started on this? What equation(s) should I...
  36. T

    Calculating Period for Simple Harmonic Motion in Physics Lab

    First, I hope this area is the right one for my question. I am working on a lab for Phyiscs I. The lab title is "Simple Harmonic Motion". Okay her is the deal and the question. My instructor told us to find the period by dividing the Time recorded by the number of oscillations (back and forth...
  37. I

    How can I find the value of phi in a simple harmonic motion equation?

    http://noether.physics.ubc.ca/physics153/assign72k5.pdf I don't get number 1 c, which equation do i use? and in general, how would I be able to find phi? OK, i figured i should find the first derivative of the displacement formula, which becomes v = -Asin(wt + phi) but that still undoable, how...
  38. C

    Simple Harmonic Motion assignment

    Hi, I'm having a few problems with an assignment. Here is the question, and the progress that I've made so far. (If you can call it progress... ) Q) A 500g cylinder of base area a=20cm^2 and height h=30cm is floating upright in water. A 50g mass resting on top of the cylinder is suddenly...
  39. D

    Show that the ball undergoes simple harmonic motion

    The problem goes as following: Solid ball (Solid sphere) of mass M and radius r is kept at the equilibrium position on a concave surface of radius R , for small displacement up the concave surface , show that the ball shows SHM motion assuming the ball rolls without slipping. I have been...
  40. E

    Simple Harmonic Motion and time equation

    Question: An object is undergoing simple harmonic motion with period 0.305 s and amplitude 6.05 cm. At t=0 the object is instantaneously at rest at x=6.05 cm. A. Calculate the time it takes the object to go from x=6.05 cm to x = -1.49 cm. I'm thinking \omega = \frac{2\pi}{T} = 20.6 rad/s. If...
  41. R

    How Do You Solve for C1 and C2 in Damped Simple Harmonic Motion?

    I'm having trouble with this problem. I want to get it into a form with cos but I'm stumped. The solution for damped simple harmonic motion is given by x = (e^(-rt/2m))(C_1*e^(iw't)+C_2*e^(-iwt)) If x = Acos phi at t = 0, find the values of C_1 and C_2 to show that x'=(approx)...
  42. E

    Finding the phase angle in simple harmonic motion

    Question: A frictionless block of mass 2.35 kg is attached to an ideal spring with force constant 310 N/m. At t=0 the spring is neither stretched nor compressed and the block is moving in the negative direction at a speed of 12.6 m/s. 1. Find the amplitude. I got this without a problem...
  43. S

    Navigating Damped and Forced Harmonic Motion

    hi guys, doing damped and forced harmonic motion at college at the moment, but i don't do further maths...hence I'm a tad behind compared to those who do (half the class). we don't need to know it for the exam itself, but you know...curiosity. does anyone know of any good online resources...
  44. C

    Question about simple harmonic motion

    A square block, with a mass of 3.40 kg and edge lengths d = 6.00 cm, is mounted on an axle through its center. A spring of spring constant k = 1190 N/m connects the block's upper corner with a rigid wall. Initially the spring is at its rest length. If the block is rotated by 3° and then...
  45. 1

    Solving Simple Harmonic Motion: Find Angular Freq & Amp.

    Question: A particle undergoing simple harmonic motion has a velocity v1 when the displacement is x1 and a velocity v2 when the displacement is x2. Find the angular frequency and the amplitutde of the motion in terms of the given quantities. The answers given in the back of the book are...
  46. D

    Simple Harmonic Motion and time period

    A particle follows SHM with its eqn.of motion being s(x,y)=Asinwt i + 3Asin3wt j What is its time period? Also find the expression for total mechanical energy wrt time. I tried it in the following way V=Awcoswt i + 3Awcos3wt j = Aw[(coswt)^2 +9(cos3wt)^2]^(1/2)...
  47. W

    2 problems on simple harmonic motion

    these are 2 qn on simple harmonic motion which i am not sure if my solution is right or not. 1) A thin rod, length L hinged at one end, connected to a spring at the other end. Take the spring constant to be K. What is the angular frequency? My solution: let the displacement from equil. to...
  48. I

    Integrating a second derivative-involving solution for Simple Harmonic Motion

    Hello, i am now in the process of integrating m(d^2x/dt^2)=-kx which i know i will have to do twice in order to obtain the general solution to simple harmonic motion, x= Acos(wt+c) c=phi but I'm just having problems with the second derivative of acceleration (d^2*x/dt^2) when it comes to...
  49. I

    Calculating Position and Distance in Simple Harmonic Motion: A Case Study

    Hi, I would really like to know if my solution to the following question is correct, I would really really really appreciate it. A hanging spring stretches by 35cm when an object of mass 450g is hung on it at rest. In this situation, we define its position as x=0. The object is pulled down an...
  50. B

    Simple Harmonic Motion of skydiver

    I can't seem to get the right answer, where is my mistake? A 90 kg skydiver hanging from a parachute bounces up and down with a period of 1.5 seconds. What is the new period of oscillation when a second skydiver, whose mass is 60 kg, hangs from the legs of the first? I am using the...
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