What is Pendulum: Definition and 1000 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timekeeper, used in homes and offices for 270 years, and achieved accuracy of about one second per year before it was superseded as a time standard by the quartz clock in the 1930s.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. S

    What happens to a pendulum clock in a lift when the cable breaks?

    I think the answer will be either (b) or (d). If the pendulum is at its amplitude when the cable breaks, then the oscillation will stop since the pendulum is also not moving at that instant. If the pendulum is at any points except amplitude, then it will hit the ceiling since it still has...
  2. E

    Two different answers for compound pendulum problem

    I completed this problem in two different ways, and wonder why they give different answers. Firstly, I calculate the moment of inertia of the system as I = 0.572 kg m^{2}, and the total torque acting on the system as 12.152 N. Thus I can apply the rotational analogue of NII to write...
  3. Like Tony Stark

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  4. Z

    Foucault Pendulum Release Velocity in Spherical Coordinates

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  5. H

    How Do Coupled Adiabatic Pendula Behave?

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  6. S

    Pendulum Clock -- Change in frequency with change in temperature

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  7. ValeForce46

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  8. S

    Tension and speed of bowling ball pendulum passing the equilibrium position

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  9. Prabs3257

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  10. dRic2

    Solve Ehrenfest's Pendulum Equation | Can't Solve It

    Well, using the above equation it should be easy... but I can't solve it :headbang::headbang: $$ L = \frac 1 2 m (\dot l^2 + l^2 \dot \theta ^ 2) - mgl(1- \cos\theta)$$ then I guess $$\int_{t_1}^{t_2} \frac {\partial L}{\partial t} dt = L(t_2) - L(t_1)$$ *Note*: since the variation ##\frac...
  11. callekula

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  12. Homgkung

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  13. michael872940

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    Classical problems for hookes law generally give either mass or spring constant. What if I have a graph of a wavelike structure that is oscillating which I can use to measure for example: T (period), t (time), Δx (displacement), v (velocity), a (acceleration) and other variables is this...
  14. S

    Direction of the net force acting on a pendulum

    I imagine y - axis is parallel to direction of A and x - axis is parallel to direction of E. There are two forces acting on the pendulum: tension in direction of A and weight in direction of D. I break the weight into 2 components: W sin θ in opposite direction to tension and W cos θ in...
  15. E

    Discontinuities in a Poincare map for a double pendulum

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  16. B

    Model Pendulum w/ Damping: Newton's Laws & Rubber Band

    I feel like this is a dumb question, but here goes: I'm trying to model a pendulum with damping. The pendulum is connected to a rubber band (unstretched when the pendulum is vertical) on the right side, and the rubber band is fixed at the other end. How would I go about modeling a rubber band...
  17. S

    Find the charge of a mass hanging from a pendulum in an electric field

    Hi, so I was able to solve this problem by just equating the forces (Tension, mg, and EQ). But I thought I could also solve this problem with Conservation of Energy. However, I calculated it several times, and I never get the right answer this way. Doesn't the Electric Field do the work to put...
  18. G

    Pendulum Hammer Impact Force Calculation

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  19. mishima

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  20. N

    Vertical circle in a pendulum ride -- tension force acting on the gondola

    At the bottom of the circle, the tension force is greater than the weight force as there must be a net force acting towards the centre to provide the centripetal force causing the centripetal acceleration and thus the circular motion. In the equation above (T = mv^2/r + mg) I only have the mass...
  21. Miles123K

    Normal mode of an infinite spring pendulum system

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  22. D

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    First, I decided to solve for the coefficient in front of the cosine simple harmonic function for velocity. I know there is max velocity of 30cm/s at time = 0 , so I plug it into velocity function. xmax * w = A v(t) = Acos(wt) 0.3 = Acos(w*0) A = 0.3 Then I have my velocity function...
  23. mishima

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  24. EEristavi

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  25. Celso

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  26. Astrogirl101

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  27. N

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    On 28 November 2018, a lecture was given by Dr. Rainer Weiss (2017 Nobel Prize Winner for Physics) at the Ontario Science Centre, Toronto. The lecture was about his work with the Laser Interferometer Gravitational-Wave Observatory (LIGO). In his lecture talked about quadruple pendulums or...
  28. Alif Yasa

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    -I tried to draw the forces on the hoop when it is in the equilibrium state. I know there are friction and normal force on the contact point of the shaft and the hoop -I also put the weight force to the M object -But when i used the torque equilibrium, where the pivot is the contact point of the...
  29. jaewonjung

    How does trigonometry help determine the gravity component on an inclined plane?

    Since gravity is acting downward, I found the gravity component parallel to the plane, which was g/sin60. I substituted g/sin60 for g into that equation and got D, but the answer should be C.
  30. Mason Smith

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  31. M

    Force on a pin from a pendulum and a string

    1. Determine the velocity of the ball when it is 30degrees from the horizontal: U1 = mgh = mg(0.8m) U2 = mgh = mg(0.4+0.4cos(30)) = mg(.74641) ΔU = U2 - U1 = mg(.74641 - .8) = mg(-0.051433) T1 =0 T2 = 0.5mv^2 ΔT = T2 - T1 = 0.5mv^2 ΔU = ΔT mg(-0.051433) = 0.5mv^2 ====> v = 1.025394 2. Use...
  32. C

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    Homework Statement A uniform rod of mass M, and length L swings as a pendulum with two horizontal springs of negligible mass and constants k1 and k2 at the bottom end as shown in the figure. Both springs are relaxed when the when the rod is vertical. What is the period T of small oscillations...
  33. MathematicalPhysicist

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    How do I guarantee that that the friction in the movement of a simple mathematical pendulum is negligible?
  34. Robin04

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  35. astroman707

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  36. brotherbobby

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    Statement of the problem : A ball shown in the figure is allowed to swing in a vertical plane like a simple pendulum. Answer the following : (a) Is the angular momentum of the ball conserved? No, the angular momentum ##L = mvl##, where m is the mass of the ball and v is its speed at an...
  37. S

    I Nonlinear Pendulum: Calculating Angular Displacement

    If I calculate the time period of a non linear pendulum using elliptical integral equation, then how can I find out the angular displacement.
  38. A

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    Homework Statement One silly thing may be I am missing for small oscillations of a pendulum the potential energy is -mglcosθ ,for θ=0 is the point of stable equilibrium (e.g minimum potential energy) .Homework Equations Small oscillations angular frequency ω=√(d2Veffect./mdθ2) about stable...
  39. S

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    Hi, I have a general question to pendulums. I hope it is ok to post it in this format. Please accept my apologies for my poor English. Homework Statement : As a general Example: I have a Pendulum of length L with Angle Theta as maximum displacement. I know how to solve these problems. Find...
  40. J

    Why Is the Third Pendulum Traveling the Fastest?

    You have a Photo of a pendulum with three pendulums. One is at an angle to the right the second Is straight down and third is at an angle to the left. The pengulum in the middle is traveling the greatest speed but why is the third one traveling the fastest ?
  41. A

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    This took a lot of time and effort and I understand if you wish to skip past everything and just read my questions about it in the The too long didn't read summary (TL;DR) at the bottom. Homework Statement The 10-g bullet having a velocity of v = 750 m/s is fired into the edge of the 6-kg...
  42. physics_cosmos

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    Homework Statement My problem/task is to explain in elementary terms the dynamics of a string coupled pendulum, the same as in this diagram: Is it simple to make a free body diagram for the pendulums? Is it possible to understand the motion as being caused by SHM oscillation of the top...
  43. Lo Scrondo

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    Hi everyone! I recently came across the Lyusternik-Fet theorem concerning closed geodesics on a compact manifold. For simplicity of description, take the 2-torus, and imagine it represents the configuration space of a double pendulum. For every pair of integers m, n (where m represents the...
  44. L

    Lagrange equation of second kind - find solution's constant?

    Homework Statement This could be a more general question about pendulums but I'll show it on an example. We have a small body (mass m) hanging from a pendulum of length l. The point where pendulum is hanged moves like this: \xi = A\sin\Omega t, where A, \Omega = const. We have to find motion...
  45. M

    Kater's Pendulum: Why Wooden/Metallic Masses Matter

    how do the two different masses (wooden and metallic) at the ends of the pendulum help?
  46. G

    Barton's pendulum, phase relationship

    Hi community, The phase relationship is 0 for the shorter pendulae, 1/4 cycle for the pendulum in resonance and in anti-phase for the longer pendulae; relative to the driver pendulum. I have observed this but I can see it conceptually to an extent but wondered if anyone knows of a resource for...
  47. E

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    Hi good day. I am trying to find the general Inverted Pendulum on a cart nonlinear state space equations with two degrees of freedom with x, x_dot, theta, theta_dot which represents displacement, velocity, pendulum angle from vertical, angular velocity. However from research, I am seeing...
  48. J

    Small oscillation frequency of rod and disk pendulum

    Homework Statement Consider a rod of length ##L## and mass ##M## attached on one end to the ceiling and on the other end to the edge of a disk of radius ##r## and mass ##m##. This system is slightly moved away from the vertical and let go. Let ##\theta## be the angle the pendulum makes with the...
  49. J

    Torque about a pendulum's suspension point

    Homework Statement In the figure attached, what is the torque about the pendulum's suspension point produced by the weight of the bob, given that the mass is 40 cm to the right of the suspension point, measured horizontally, and m=0.50kg? Homework Equations tau = rFsin (theta) or tau = lF...
  50. K

    Max. acceleration of a pendulum changes with its length and mass?

    Hi, If I find out the tangential force on the bob at position 1, it turns out to be m*g*sinθ. From this if I find out acceleration by dividing this equation by m, I get only g*sinθ. Does it mean the max acceleration of pendulum has got nothing to do with its length or mass but theta?
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