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Oscillations

  • G1-51: INVERTED SPRING PENDULUM

    G1-51
    Illustrate a form of periodic vibration.
    A mass is attached to the top of a rigid metal rod. Tweak the mass to start the motion. This is a good approximation to SHM with damping. Invite students to discuss how this is similar to, and differs from, the classic examples.
    FS2

  • G1-52 STRINGLESS PENDULUM

    G1-52
    Demonstrates an example of SHM
    The ball rolls back and forth in the trough, executing SHM.
    G1

  • G1-53: SHM - CAN IN WATER TANK

    G1-53
    Demonstrate one form of SHM.
    A weighted cola can floats as shown in a tank of water. When displaced from its equilibrium position and released, it executes SHM. Due to the viscosity of the water, there is considerable damping.
    G1, F1

  • G1-54: MASS'S DOUBLE PENDULUM

    G1-54
    Demonstrate the transition of potential energy into energy of oscillation of the pendulum, and the operation of an escapement.
    Put your finger into a hole of a toothed wheel and rotate it counterclockwise 2 or 3 turns to give the spring energy or to lift the weight. For this purpose disconnect the wheel with anchor by pressing its axis. When this wheel is released, the pendulum starts to oscillate. This demonstrates one mechanism by which energy is fed into the pendula of large clocks.

    You can see a working simulation of the physics behind a clock escapement here: https://www.myphysicslab.com/engine2D/pendulum-clock-en.html

  • G1-55: INERTIA BALANCE

    G1-55
    Illustrate the measurement of inertial mass using SHM.
    A mass is placed on the platform and set into motion, executing SHM horizontally. The period of the oscillation T = (1/2 pi) SQRT ((M+m)/k), where M is the mass of the platform and m is the unknown mass. Making period measurements with and without the unknown mass m one can determine its inertial mass.
    G1, ME1

  • G1-56: INVERTED PENDULUM - SABER SAW

    G1-56
    Show the inverted pendulum dramatically.
    A rigid rod with a ball on the end is mounted vertically upward from its pivot point, which is the blade mount of a saber saw. If the pivot point is oscillated vertically at a rapid frequency with a small amplitude, the pendulum will have a stable equilibrium position vertically upward, and will slowly execute simple harmonic motion about that position.

    Click here to see a simulation of an inverted pendulum by Erik Neumann.
    OS11

  • G1-57: INVERTED PENDULUM - SPEAKER DRIVEN

    G1-57
    Demonstrate the conditions for stability of an inverted pendulum.
    A weighted straw hinged at the center of a loudspeaker is used as an inverted pendulum, which is driven by a sinusoidal wave to the speaker. The effect of variation of the driver frequency and amplitude on the stability can be easily studied.

  • G1-58: LOADED PENDULUM

    G1-58
    Analog to the longitudinal motion of a particle in a particle accelerator driven by a sinusoidal accelerating potential.
    The position of the pendulum bob, displaced from the vertical by the hanging weights, represents the phase of a particle being accelerated in a particle accelerator. The sinusoidal accelerating voltage creates oscillations of the particle about its equilibrium phase. The phase of the accelerating particle oscillates about the equilibrium phase, as does the pendulum.

  • G1-59: BIFILAR PENDULUM

    G1-59
    Illustrate a system with two pendular modes of oscillation.
    A ball is suspended by a string attached to another string which hangs from a support rod as shown in the photograph. In one direction the pendulum swings with a short length while in the orthogonal direction it swings with a much longer length. When the ball is moved in any other direction and released the resulting motion is a combination of these two orthogonal modes.

  • G1-71: LISSAJOUS FIGURES - SAND PENDULUM

    G1-71
    Demonstrate Lissajous figures.
    The bob is filled with sand, displaced from equilibrium and released or gently pushed. Its bifilar suspension causes it to execute Lissajous figures, which are traced out by the released sand.

  • G1-73: LISSAJOUS FIGURES - FOURIER SYNTHESIZER

    G1-73
    Show stable Lissajous figures.
    Various harmonics from the Fourier synthesizer are input into the horizontal and vertical inputs of an oscilloscope, creating Lissajous figures. Any ratio of harmonic numbers can be used (including two first harmonics) with their phases and amplitudes independently adjustable.
    You can get a neat effect by using the "dot" display style and a 2.50 second variable persistence. Change the phase of one of the inputs and watch the pattern change! Two examples are shown below
    H1, ME2

  • G1-74: LISSAJOUS FIGURES - LASER AND LOUDSPEAKER

    G1-74
    Show Lissajous figures created by music to form a laser show.
    A front-surface mirror is suspended in front of the center of a large loudspeaker in an orthogonal suspension. A laser beam bounces off the mirror onto a nearby white screen, creating varying Lissajous patterns as the music plays. This suspension encourages the mirror to move with two basically orthogonal oscillations, combining to form Lissajous figures, as seen above.
    OS5

  • G1-81: OUIJA WINDMILL

    G1-81
    Illustrate a combination of simultaneous orthogonal oscillations.
    Stroke the notches with the V-shaped section on the stroker stick. The end pin will execute circular or elliptical motion, causing the propeller to rotate. Rubbing either your thumb or your forefinger on the stick (by sliding your hand slightly back and forth) reverses the phase of the horizontal oscillation with respect to the vertical oscillation of the pin, causing the rotation of the pin and the propeller to reverse.

    This was once a popular toy, and has been used in "demonstrations" of psychokinetic abilities. This demonstration can be used to discuss how unexpected behaviour or difficult-to-observe variables can be used to confuse or mislead observers.

  • G1-82: PENDULUM WAVES

    G1-82
    Create waves in a very dramatic way using a series of fifteen carefully adjusted independent pendula.
    After the pendula are started into oscillation with the same phase, they pass through a series of various standing wave and traveling wave patterns, finally returning to their initial mode, in which they were all in phase. This is a GREAT demonstration - takes about one minute.

  • G1-83: PENDULUM WAVES - COMMERCIAL VERSION

    G1-83
    Create waves in a very dramatic way using a series of carefully adjusted pendula of various lengths.
    This is a commercial version of our demonstration G1-82: Pendulum Waves. After the pendula are started into oscillation in phase, they pass through a series of various standing wave and traveling wave patterns, finally returning to their initial mode, in which they were all in phase.

  • G2-01 MASS ON SPRING - HAND HELD

    G2-01
    Demonstrates resonance and phase shift at resonance
    The mass on the spring has a natural frequency, which can be demonstrated by simply holding one end of the spring a rest and allowing the mass to oscillate freely. Demonstrate resonance as follows: (1) With the mass hanging at rest, move your hand very slowly up and down. The mass follows your hand, showing that the mass and the driving force stay in phase for driving frequencies far below the natural frequency of the oscillator. (2) With the mass hanging at rest, move your hand very rapidly up and down. The mass moves opposite to your hand, showing that the mass and the driving force stay out of phase for driving frequencies far above the natural frequency of the oscillator. (3) Move your hand up and down at the natural frequency of oscillation; the phase relationship for resonance is that motion of the driver (hand) must be 90 degrees ahead of the motion of the oscillator. With an almost imperceptible oscillation of your hand, the resonance condition causes the mass on spring to begin to oscillate with a very large amplitude.
    G2

    G2-01A

  • G2-02: FORCED HARMONIC MOTION WITH DAMPING - LARGE

    G2-02
    Demonstrate and graph driven and damped harmonic motion.
    Variable speed motor can be run below, at, or above the resonant frequency of a mass hanging on the spring. Two masses are provided. Inserting a felt-tipped pen into the holder and starting the paper rolling allows you to graph the motion of the oscillating mass.

    Note that this has been largely replaced by G2-09.

  • G2-03: RESONANCE IN TORSIONAL PENDULUM - PROJECTION

    G2-03
    Demonstrate quantitatively all aspects of the driven and damped oscillator.
    Using the "gross" and "fein" controls on the power supply box the frequency of the driving force can be swept through the natural frequency of the rotator. A knob on the power supply controls a damping magnet. Driven oscillations, under-damped, over-damped, and critically damped motion can be shown, and the maximum amplitude in the presence of various damping forces can be ascertained. A light source is optionally available for shadow projection.

    Practice before demonstrating this device. It is a very inclusive machine, and can be used to illustrate most aspects of damped and driven oscillations discussed in intermediate mechanics texts.

    Do not exceed the allowable damping voltage for more than a few seconds at a time, or the magnet may burn out.
    G2, ME2, LS1

  • G2-04: DAMPED OSCILLATIONS

    G2-04
    Demonstrate damped harmonic oscillations.
    Pull down or lift up the aluminum mass on the end of the spring and release to obtain oscillations. Moving the magnet so that the aluminum bar moves in the magnet gap creates very strong eddy current damping. By inserting a pen into the holder and scrolling the paper roll with the motorized drive, a graph of damped harmonic oscillation can be drawn.

    See G2-09 for the updated version of this demonstration.

  • G2-05: AIR TRACK - DRIVEN AND DAMPED OSCILLATIONS

    G2-05
    Illustrate the behavior of a driven and damped oscillator.
    A moveable glider, attached by stretched strings to a fixed glider at the left and an oscillator motor at the right, executes SHM when displaced and released. The oscillator can be driven by the variable frequency motor driver and damped by eddy currents by placing a magnet close to the base of the moving glider. The natural frequency of the glider can be changed by adding mass to the glider or by increasing the spring tension.