What is Simple pendulum: Definition and 199 Discussions

A pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force acting on the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum and also to a slight degree on the amplitude, the width of the pendulum's swing.
From the first scientific investigations of the pendulum around 1602 by Galileo Galilei, the regular motion of pendulums was used for timekeeping, and was the world's most accurate timekeeping technology until the 1930s. The pendulum clock invented by Christiaan Huygens in 1658 became the world's standard timekeeper, used in homes and offices for 270 years, and achieved accuracy of about one second per year before it was superseded as a time standard by the quartz clock in the 1930s. Pendulums are also used in scientific instruments such as accelerometers and seismometers. Historically they were used as gravimeters to measure the acceleration of gravity in geo-physical surveys, and even as a standard of length. The word "pendulum" is new Latin, from the Latin pendulus, meaning 'hanging'.

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  1. N

    Simple pendulum equation of motion

    Hi! I've been trying to find the equation of motion for the simple pendulum using x as the generalized coordinate (instead of the angle), but I haven't been able to get the right solution... Homework Statement The data is as usual, mass m, length l and gravity g. The X,Y axes origin can be...
  2. T

    Simple Pendulum: The gradient of the graph of T^2 against length

    I've been asked to investigate the value of g. My graph shows that the gradient is around 4.4 as when the length was 0.27m, the squared time period was 1.18s (since this is a T2 against L graph). My question is, of course, why? If I am detecting g, which is 9.81 on earth, why did I get such...
  3. T

    Calculating the Period of a Simple Pendulum

    A simple pendulum is suspended from a ceiling 3.2m high and the bob height from the floor is measured to be 68cm. Calculate the period of small amplitude oscillations of the bob. I converted 68cm to 0.68m. The total length of the pendulum must be 3.2 - 0.68 = 2.52. When working with the...
  4. T

    Simple Pendulum Damping: Finding Amplitude and Energy Loss Rate

    Homework Statement Consider a simple pendulum (point mass bob) 0.55m long with a Q of 370. a) How long does it take for the amplitude (assumed small) to decrease by two-thirds? b) If the amplitude is 2.9cm and the bob has mass 0.22kg , what is the initial energy loss rate of the pendulum...
  5. T

    Full solution for the simple pendulum

    Having recently completed a session on the simple pendulum in physics, I was curious as to what the solution to θ''+(g/l)sin(θ)=0 for θ(t) was sans the sin(θ)=θ simplification.
  6. T

    Simple Pendulum in Elevator: Calculating Angular Amplitude with Acceleration

    Homework Statement A simple pendulum of length l is tied to the ceiling of an elevator which is at rest. The pendulum is oscillating with a time period T, and it has an angular amplitude β. Now at some time when the bob of the pendulum is at the mean position, the elevator suddenly starts...
  7. S

    I need the parametric equations for a simple pendulum

    This is for a personal engineering project. I need the parametric equations y(t) and x(t) for a very simple pendulum. Assume no friction, no forcing, no variation in gravity, a point mass, and the tether angle is significantly less than 30 degrees. It has been a while since I did differential...
  8. I

    Simple Pendulum Amplitude Investigation: Graph and Uncertainty Analysis

    As part of a Physics experiment I have to investigate how the amplitude of a pendulum bob (attached to a string) varies with the number of oscillations it undergoes. The equation I have to work with is: (where t = the number of swings, A = amplitude after t swings, A0 = initial...
  9. M

    Simple pendulum with initial velocity

    Hi, I've attached a couple questions just because these are the type of questions I've had some difficulty solving since I don't recall addressing anything too similar too similar in the past (i.e., changing velocity and determining how the amplitude varies because of this). I know to go from...
  10. P

    Simple Harmonic Motion: Simple Pendulum

    If we apply the small angle approximation so that a simple pendulum can be considered to be under going SHM, what kind of potential energy would the pendulum bob be having? If the answer is gravitational potential energy, then we have a contradiction because this would mean that the bob would...
  11. deedsy

    Calculating Kinetic and Potential Energy for Simple Pendulum - Homework Problem

    Homework Statement A simple pendulum consists of a point mass m suspended from a fixed point by a weightless rigid rod of lengh l. The kinetic energy = 1/2*m*l^2*(dθ/dt)^2 The potential energy = -m*g*l*cosθ Calculate the time averages of the kinetic and potential energies over one...
  12. N

    Simple pendulum- ang v at time from mass, length, and ang v at 0 rad

    Homework Statement A pendulum consists of a 300 gram mass attached to the end of a string of length 75 cm. • a) Using the small angle approximation(sinθ ≈ θ), derive an equation for the angular acceleration of the pendulum, assuming that there is no friction. • b)] The pendulum is given a...
  13. B

    Simple pendulum, changing amplitude vs changing the length of string

    Hello, I don't understand how changing the amplitude does not change the period but changing the length of the string does. Each changes the height and changes the arc length so wouldn't they both change the period? Thank you for any help!
  14. J

    Relationship of simple pendulum

    hi guys, I'm currently working on a physics report about a simple pendulum and can't figure out how to answer one of the questions: 3. "define all terms in the solution(x(t)=Acos(ωt)) and especially the relationship between angular frequency, and periodic time, T." ive defined all the...
  15. E

    Simple pendulum Help. Dunno Why Im wrong.

    Homework Statement A very light rigid rod with a length of 0.742 m extends straight out from one end of a meter stick. The combination is suspended from a pivot at the upper end of the rod as shown in the following figure. The combination is then pulled out by a small angle and released...
  16. C

    MHB Simple pendulum with air resistance

    Im getting stuck on a couple of the questions for my mechanics homework. Il put what I've done so far and hopefully someone can check I am doing it right n push me into the right direction for the rest. "A grandfather clock has a simple pendulum...
  17. S

    Amplitude in a simple pendulum - angle or distance?

    Is amplitude in a simple pendulum measured as an angle, theta, or as a distance? If it is an angle, is it in radians or degrees. Also, what is the equation? How does amplitude relate to x=Acos(ωt)?
  18. PhizKid

    Max velocity for simple pendulum oscillation

    Homework Statement Show that v_max = w_max * Length of string where v_max is the velocity of the simple pendulum and w_max is the maximum angular velocity. Homework Equations \omega_{velocity} = -\theta_{max} \cdot \omega_{frequency} \cdot sin(\omega_{frequency} \cdot t + \phi) The...
  19. PhizKid

    How to get max velocity for simple pendulum

    Homework Statement A simple pendulum has a ball at the end of mass 5 kg and the length of the string is 5 m. Given \theta = 0.0800 \cdot cos[4.43t + \phi] find the maximum velocity Homework Equations \frac{1}{2}mv^2 = \frac{1}{2}kA^2 The Attempt at a Solution \frac{1}{2}mv^2 =...
  20. C

    Lagrangian of Simple Pendulum with Fixed Masses and Horizontal Bar

    Homework Statement 2 masses, m_{1} and m_{2} are fixed at the endpoints of a rigid rod of length l. mass m_{1} is attached to a horizontal bar so that it may move in the x direction freely, but not in the y direction. let θ be the angle the rod makes with the vertical, what is the...
  21. M

    Scaling factor of a simple pendulum between length and time period.

    Homework Statement The time period of a simple pendulum is doubled when the length of the pendulum is increased by 3.0m. What is the original length of the pendulum? Homework Equations T= 2∏√(l/g) also l is original length and l+3 is the new length The Attempt at a Solution So...
  22. U

    Simple pendulum falling freely

    Homework Statement The free end of a simple pendulum is attached to the ceiling of a box. The box is taken to a height and the pendulum is oscillated. When the bob is at its lowest point, the box is released to fall freely. As seen from the box during this period, the bob will a)continue...
  23. P

    Finding Tension in Simple Pendulum at 20 Degrees Angle | Physics Homework

    Homework Statement http://img32.imageshack.us/img32/1551/filevno.jpg I have to find the tension for the rope when angle is 20 degrees, the object is moving back and forth. I know the mass is 2kg, gravity is 10N/kg Homework Equations F_t * cos θ = mg. So F_t = mg/cos θ The...
  24. E

    Eddy Current Braking of a Simple Pendulum

    I'm setting up an experiment and I 'd like to somehow quantify the effects of magnetic braking on a simple pendulum. At the moment, I have a curved sheet of Aluminium that I will swing freely between two magnets set up in yoke (horseshoe magnets). The magnets induce eddy currents in the...
  25. S

    Simple Pendulum nonlinear second order differential equation

    Homework Statement given: dt=-\frac{1}{2}\sqrt{\frac{l}{g}}\frac{d\theta}{\sqrt{sin^2(\alpha/2)-sin^2(\theta/2)}} make the change of variables sin(\theta/2)=sin(\alpha/2)sin(\phi) to show that: dt=-\sqrt{\frac{l}{g}}\frac{d\phi}{\sqrt{1-k^2sin^2(\phi)}} where k=sin(\alpha/2) Homework...
  26. R

    REAL QUICK question about how to solve for the period of a simple pendulum?

    REAL QUICK question about how to solve for the period of a simple pendulum? For part a, I tried using the formula: T = 2π√(L/g) I did, T = 2π√(53.4/9.8) T = 2π√(5.44) T = 2π(2.33) T = 14.6 s But that's wrong... Help please?
  27. S

    Simple pendulum with friction ODE

    I'm trying to figure out how to find the general solution for a simple pendulum with friction. y'' + ky' + (g/L)y = 0 I know how to find the solution for a simple pendulum without friction: y'' = -(g/L)y ... which leads to ... y = Acos((g/L)x) So far I have: y'' + ky' + (g/L)y =...
  28. T

    MATLAB Plotting Simple Pendulum in MATLAB: Tutorials & Tips

    I'm really confused at the moment and would quite appreciate some guidance. I've got little to no background in Matlab and am needing to plot a simple pendulum. I have found the equation of motion which is q(doubledot) = -(g/l)sin(beta) I don't know how to go about this? After...
  29. X

    Classical mechanics, simple pendulum

    Homework Statement See attachment "question" Homework Equations The Attempt at a Solution See attachment "work" I did the work for (1) and (2). I end up with two equations: the first is the tension T, the second is the angular acceleration. I'm not so sure if I made any...
  30. X

    Simple pendulum dynamics; equations of motion, work and energy

    Homework Statement See attachment "problem" Homework Equations Euler's laws of motion (moment equations), work and energy equations The Attempt at a Solution See attachment "work" I did the work for (1) and (2). I end up with two equations: the first is the tension T, the second...
  31. H

    Simple Pendulum SHM Problem: Calculating Angular Frequency for Maximum Amplitude

    Homework Statement Consider, as shown in the picture, a penulum of mass m=0.52g, hanging on an ideal rope of length l=0.31m. A force is exerted to this pendulum as shown in the picture. The horizontal component of the force is: \displaystyle {{F}_{x}}={{F}_{0}}\cos \left( \omega t \right)...
  32. A

    Tension in a string simple pendulum

    Homework Statement Hi Guys I obtained a slighty different answer. Can anyone kindly verify where I am going wrong? The question is stated thus: A simple pendulum is of length 0.5m and the bob has mass 0.25kg. Find the greatest value for the tension in the string when the pendulum is set...
  33. G

    Time Period of Halved Simple Pendulum

    when we half the length of simple pendulum what will be its time period?please reply
  34. R

    Simple Pendulum Centripetal Acceleration

    Homework Statement http://screensnapr.com/v/tC6gC3.jpg Homework Equations Im guessing: Centripetal Acceleration = v^2/r PE = mgh KE = .5mv^2 The Attempt at a Solution I tried to convert the givens into velocity by using .5mv^2, but that does not work.
  35. H

    Simple Pendulum: Amplitude, velocity, and angular position.

    θθHomework Statement A simple pendulum of mass 20.0 g is suspended by a length of string 1.0 m. It is pulled from equilibrium so that it's raised 10.0 cm and released. Angular position given by θ(t)=θmaxcos(ωt+∅) What is the period? What is the maximum velocity of the pendulum? What is the...
  36. P

    Derivation of simple pendulum formula

    You pull a simple Pendulum of length 0.240 m to the side through an angle of 3.5 degrees and release it. (a) How much time does it take the pendulum bob to reach its highest speed? (b) How much time does it take if the pendulum is released at an angle 1.75 degrees instead of 3.5 degrees?
  37. fluidistic

    Lagrange multipliers in a simple pendulum

    Homework Statement Not really a homework question, just want to check out if what I'm doing is right. I challenged myself to find the equation of motion and the forces in the simple pendulum system but with using the Lagrange multipliers and the constraint equation.Homework Equations In next...
  38. S

    Calculating G: Simple Pendulum Experiment, problems?

    I need to experimentally calculate gravity (g) with an extreme precision (+/-0,005). We thought about trying an Atwood Machine but too many problems were related to it so we've decided to switch to an Simple Pendulum (with a very long L). What are the problems related to the Simple Pendulum...
  39. F

    Simple Pendulum Amplitude and Frequency Changes Due to Mass Variation

    Homework Statement You and your friend sit on the same swing and oscillate about the equilibrium position. Your friend falls off the swing exactly at the highest point (largest amplitude). What will happen to the amplitude and frequency of your oscillation ? (a) the amplitude stays the...
  40. A

    Expression for time period of simple pendulum

    Which of the two is a better expression for the time period of a simple pendulum? t-=2∏\sqrt{(l/g)} or t=2∏\sqrt{(1/T/m)} ; l=length of the pendulum T=time period of the pendulum m=mass of bob...
  41. G

    Finding the period of a simple pendulum given angular acceleration

    Homework Statement A physical pendulum oscillates through small angles about the vertical with the angle, measured in radians, obeying the differential equation d2θ/dt2 = -4πθ. What is the period of the oscillation? Homework Equations T = 2π √(L/g) The Attempt at a Solution I...
  42. R

    Period of a Simple Pendulum with Varying Masses and Gravitational Forces

    Homework Statement The usual formula for the period T of a simple pendulum of length l is T=2\pi\sqrt{\frac{l}{g}} where g is the acceleration due to gravity. Denoting rhe inertial mass of the pendulum bob by m_{i} and its gravitational mass by m_{g}, derive an alternative expression for T in...
  43. J

    Speed of Pendulum Bob at Lowest Point

    Homework Statement A simple pendulum consists of a bob of mass 1.8kg attached to a string of length 2.3m. The pendulum is held at an angle of 30° from the vertical by a light horizontal string attached to a wall. If the horizontal string is cut close to the bob and the pendulum swings down...
  44. C

    Calculating the Acceleration of a Simple Pendulum

    Homework Statement A simple pendulum has a length of 4.9 m and is pulled a distance y = 0.5 m to one side and then released. (a) What is the speed of the pendulum when it passes through the lowest point on its trajectory? (b) What is its acceleration when it passes through the lowest...
  45. B

    How to Calculate g with Known Pendulum Length and Negligible Amplitude?

    How to calculate g if amplitude of a simple pendulum is negligible and the length is known? T=2π\sqrt{}l/g
  46. A

    Deriving the Equation for Period of Simple Pendulum? Is my attempt correct?

    Homework Statement I have to derive an equation with the following variables: T= period m= mass Theta= angle l= length and I was told to think of the period as the perimeter of a circle.Homework Equations The Attempt at a Solution C=2\pi r,C/2=\pi r,d=\pi r,(at^2)/2=\pi r,t=\sqrt{\frac{2\pi...
  47. B

    Frequency of a simple pendulum

    A simple pendulum of length L and mass m is suspended in a car that is traveling with constant speed v around a circle of radius R. If the pendulum undergoes small oscillations in a radial direction about its equilibrium position, what will its frequency of oscillation be? I don’t know how to...
  48. A

    Uncertainty with a simple pendulum

    A simple pendulum is used to measure the acceleration of gravity using T=2pi(sqrt(L/g)) . The period T was measured to be 1.24 ± 0.02 s and the length L to be 0.381 ± 0.002 m. What is the resulting value for g with its absolute and relative uncertainty? So the first thing I did was to isolate...
  49. I

    Energy conservation in simple pendulum

    Hello everyone! I've found this problem in my exercises book, and I'm having slight troubles solving it. "Consider a simple pendulum with mass m, on a string with l length. Considering that the position of pendulum is determined with the angle \theta and noting that the string DOES NOT do any...
  50. A

    Simple Pendulum Problem: Finding Coefficient of Linear Expansion

    Homework Statement A simple pendulum whose string is made of some unknown material loses 5 seconds per day at 15 deg and gains 10 seconds at 30 deg. What is the alpha i.e. coefficient of linear expansion of this material? Homework Equations [b]3. The Attempt at a Solution [/b I...
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