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PHYS122

  • G1-01 EXAMPLES OF SIMPLE HARMONIC MOTION

    G1-01
    Illustrates simple harmonic motion

    This demonstration lets you compare three typical pendula: a simple pendulum (mass on string), a physical pendulum (swinging rod), and a mass on a spring. Any of these produce simple harmonic motion, with a variety of periods. Useful for showing that the same equation describes the motion of any type of oscillating body.
    You can also compare these real-world pendula with some simulated ones:
    1. Erik Neumann's Single Spring simulation
    2. Erik Neumann's Pendulum simulation
    3. PhET Masses on Springs
    4. PhET Pendulum Lab
    FS2

  • G1-11 COMPARISON OF SHM AND UCM

    G1-11
    Demonstrates the relationship between simple harmonic motion and uniform circular motion.
    Turning a crank on the rear of the apparatus causes the center ball to move in circular motion around a 30cm diameter orbit, while the ball on top executes simple harmonic motion. It can be seen that SHM is the projection of UCM. This device can also be used to discuss the concept of degrees of motion in SHM by comparison with the reference circle.

  • G1-14 PENDULA WITH DIFFERENT MASSES

    G1-14
    Demonstrates independence of a simple pendulum's period with mass of the bob.
    Four geometrically identical pendula have bobs made from lead, brass, stainless steel, and aluminum, respectively. Their periods are the same.
    FS2

  • G1-15 PENDULA WITH 4 TO 1 LENGTH RATIO

    G1-15
    Shows that period of a simple pendulum is proportional to the square root of its length
    The two pendula are started in phase. The shorter pendulum undergoes two complete oscillations for each oscillation of the longer pendulum.
    FS2

  • G1-17: PENDULUM WITH LARGE-ANGLE OSCILLATION - PORTABLE

    G1-17
    Illustrate large-angle pendular oscillations and the 360 degree pendulum.
    The motion of a small-angle oscillation can be compared with large-angle oscillations. The motion of a 360 degree pendulum with just enough energy to execute complete circles can be observed or compared with calculations.

  • G1-33 MASSES AND SPRINGS WITH SPIDER

    G1-33
    Compares frequencies of various mass-spring combinations
    Hang various masses on various springs and observe the oscillations. Notice that the damping is greater for the mass on the rubber band.
    FS1

  • 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

  • G2-05: 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.

  • G2-11: RESONANT SAW BLADES - HAND DRIVEN

    G2-11
    Show that a mechanical oscillator responds with a maximum amplitude to its own resonant frequency.
    Three saw blades of different lengths have been rigidly attached to a manual shaker. Shaking the assembly, one can find the resonant frequency of each saw blade.

    For a similar power-driven demonstration, see G3-45.
    G2

  • G3-01 SHIVE WAVE MACHINE - TRAVELING WAVES

    G3-01
    Demonstrates traveling waves

    Make sinusoidal waves by moving the spines at one end of the machine up and down sinusoidally, either with your hand or using the wave generator. Vary the amplitude and the frequency and observe the wavelength. You can show semi-quantitatively that the wave speed is approximately the same for all frequencies.
    Background
    The Shive wave machine illustrates transverse waves - the direction of displacement is perpendicular to the direction of transmission. This can be used as a model of many wave phenomena.
    FS0

  • G3-02: SHIVE WAVE MACHINE - SUPERPOSITION OF PULSES

    G3-02
    Demonstrate constructive and destructive interference using pulses.

    Starting identical pulses from both ends simultaneously, either in or out of phase, they can be observed as they pass. For two identical pulses, move your hand rapidly down and up at the center of the machine with the two ends fixed. The two pulses created will reflect off the ends (left photograph) and interfere constructively as they cross each other on their return (right). Repeat this with one end clamped to get a phase reversal of the pulse which reflects off that end.
    Engagement Suggestion
    • This is a good opportunity to bring up one or two volunteers from the class to participate, rather than trying to reach both ends simultaneously yourself.
    • Encourage the class to predict what will happen when the pulses pass each other.
    Background
    In a linear medium like this, two waves moving in opposite directions can be seen to pass through each other. The principle of superposition states that when two mechanical waves pass each other in a medium, the net displacement at any point is the sum of the individual wave displacements.
    Ofc

  • G3-03: SHIVE WAVE MACHINE - REFLECTION OF PULSES

    G3-03
    Demonstrate reflection of pulses from fixed ends and free ends.

    A pulse generated at the left end (photograph at left) reflects off the right end. The reflecting end can either be fixed (clamped, center photograph) or free (right photograph).
    Engagement Suggestion
    • Encourage students to make a prediction before each combination as to whether the wave will reflect, and whether that reflection will be upright or inverted. • This can be combined with demonstration G3-05, showing that fixed and free end reflections are the extreme cases of partial reflections due to a change in impedance.
    Background
    Like any wave in a transmission medium, when the medium ends the energy in the wave has to go somewhere. The wave is reflected back from the end. With a free end, the wave reflects identically; with the end clamped, it reflects inverted.

    g3-03 g3-03a g3-03b

  • G3-04: SHIVE WAVE MACHINE - STANDING WAVES

    G3-04
    Demonstrate standing waves.

    Standing waves can be generated with either (1) both ends fixed, (2) one end fixed and one end free, or (3) both ends free. You can use either your hand or the motorized drive; your hand possesses better feedback for small adjustments in frequency.
    A metronome is available upon request for comparing the frequencies of various harmonics, or you can time them using the classroom clock or computer.
    Engagement Suggestion
    • Ask students to make predictions before each configuration of the device. Will fixed ends, free ends, or one open and one free end have the longest wavelength fundamental?
    Background
    A standing wave oscillates in time, but the peaks do not travel in space. A standing wave can be created in a mechanical medium of fixed length with an oscillation at that medium's natural frequency, or a multiple thereof.

    g3-04 g3-04b g3-04d

    g3-04a g3-04c g3-04e

  • G3-05: SHIVE WAVE MACHINE - PARTIAL REFLECTIONS

    G3-05
    Show that a wave will be partially reflected at a point where the impedance changes.

    The Shive Wave Machine illustrates transverse waves traveling down a torsional wire. Partial reflection can be produced by
    • • linking the two different segments as shown in the photograph,
    • • adding weights to the end of a central crossarm to produce an impedance glitch, or
    • • attaching the dashpot at a central location and adjusting it for partial absorption of the incoming wave.
    Background
    Changing the arm mass changes the impedance of the medium. This changes the transmission speed; and when a wave passes through the junction, it may be partially reflected. Like a reflection from a free or fixed end (G3-03), this partial reflection can also be upright or inverted. Passing from higher to lower impedance gives an upright partial reflection; passing from lower to higher impedance gives an inverted partial reflection.

  • G3-24: SLINKY ON LECTURE TABLE - TRAVELING WAVES

    G3-24
    Show travelling waves.
    One end of the SLINKY is taped to the lecture table while theother end is free to move for creating waves. For best waves do not overextend the SLINKY.
    G3

  • G3-26: AIR TRACK - LONGITUDINAL WAVES

    G3-26
    Demonstrate longitudinal waves with a series of spring-coupled air track gliders.
    Several identical gliders are connected by springs, with the two end gliders fixed or attached by springs to the ends of the air track. Longitudinal waves can be created which reflect off the (fixed) ends, and standing waves can be created in the system.

  • G3-27: AIR TABLE - TRANSVERSE AND LONGITUDINAL WAVES

    G3-27
    Demonstrate transverse and longitudinal waves using an air table.
    Identical pucks are attached by light springs diagonally across the air table. Either transverse or longitudinal waves can be created by hand in this system.

  • G3-28 SUSPENDED SLINKY

    G3-28
    Shows longitudinal and transverse traveling waves & standing waves
    Transverse or longitudinal pulses can be created by appropriate motion of your hand at one end of the SLINKY. Using your hand you can also create transverse standing waves and discuss the overtone series. Gently vibrating one end of the spring (either by hand or using the motor) at the appropriate frequency creates longitudinal standing waves.
    FS1

  • G3-29: SUSPENDED SLINKY - PORTABLE

    G3-29
    Show longitudinal and transverse traveling waves and standing waves.
    Transverse or longitudinal pulses can be created by appropriate motion of your hand at one end of the SLINKY. Using your hand you can also create transverse standing waves and discuss the overtone series. Gently vibrating one end of the spring at the appropriate frequency creates longitudinal standing waves.
    OS0

  • G3-51 ROPE WAVE GENERATOR - FREQUENCY VS. WAVELENGTH

    G3-51
    Shows the relationship between frequency and wavelength for fixed tension cord
    Keeping the tension in the rope fixed (same weight on hook) and raising the frequency creates standing waves with shorter wavelength (more loops).
    FS1