DOCSLIB.ORG

On the Sound Field Radiated by a Tuning Fork

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
On the Sound Field Radiated by a Tuning Fork On the sound field radiated by a tuning fork Daniel A. Russell Science and Mathematics Department, Kettering University, Flint, Michigan 48504 ͑Received 14 June 1999; accepted 25 April 2000͒ When a sounding tuning fork is brought close to the ear, and rotated about its long axis, four distinct maxima and minima are heard. However, when the same tuning fork is rotated while being held at arm’s length from the ear only two maxima and minima are heard. Misconceptions concerning this phenomenon are addressed and the fundamental mode of the fork is described in terms of a linear quadrupole source. Measured directivity patterns in the near field and far field of several forks agree very well with theoretical predictions for a linear quadrupole. Other modes of vibration are shown to radiate as dipole and lateral quadrupole sources. © 2000 American Association of Physics Teachers. I. INTRODUCTION II. THE TUNING FORK AS A LATERAL QUADRUPOLE If one rotates a sounding tuning fork once about its long A typical explanation of the sound field produced by a axis while holding the fork close to the ear, one finds four tuning fork goes something as follows.2,3,5,8 positions where the sound is loud, alternating with four po- 1 When the tines move outward, a compression is sent out in sitions where the sound is very quiet. The loud regions are the directions of A in Fig. 1͑b͒ and simultaneously a rarefac- indicated as A and B in Fig. 1͑b͒ and the quiet regions fall tion in the directions of B. As the tines move inward they approximately along the dotted lines. By rotating the fork send out a rarefaction in the directions of A and a compres- close to the end of a tuned resonance tube this phenomenon sion in the directions of B. These sets of waves are always in may be demonstrated to a group of people.2,3 If one listens opposite phase, and along the directions 45° from the plane very carefully, one finds that maxima in the plane of the fork of the tines ͑dotted lines͒ the compressions of one set of ͓regions A in Fig. 1͑b͔͒ are noticeably louder than those waves and the rarefactions of the other will coincide, and perpendicular to the fork ͑regions B͒. there will be silence. A very different pattern of loud and quiet regions is heard, As an example of a sound source which follows the above description, consider a cylinder whose radius alternately ex- however, when a sounding tuning fork is held at arm’s length 9 from the ear and rotated once about its long axis. Now, only pands and contracts according to two maxima are heard, both in the plane of the fork ͑regions r͑␪,t͒ϭRϩcos͑2␪͒sin͑␻t͒, ͑1͒ A͒, while minima are heard perpendicular to the fork ͑re- ͒ where R is the mean radius of the cylinder. Figure 2 shows gions B . The differences between near- and far-field sound one cycle of the radial oscillation of the cylinder. The cylin- patterns may be effectively demonstrated to a larger audience der simultaneously elongates in the horizontal direction, by using an inexpensive microphone and preamp connected pushing air outward, and contracts in the vertical direction to an oscilloscope. drawing air inward. Half a cycle later the cylinder contracts While several older acoustics texts describe the sound in the horizontal direction drawing air inward and expands in field radiated by a tuning fork,1–6 discussion of this phenom- the vertical direction pushing air outward. Figure 3 shows enon is absent from recent acoustics texts. Unfortunately, two frames from an animation created with those older texts which attempt to explain the sound field MATHEMATICA,10,11 which shows the sound field resulting close to the fork do so in terms of constructive and destruc- from Eq. ͑1͒. The animation is available as an animated GIF 12 tive interference effects. This would seem an implausible movie on the WWW. The two still frames differ by one explanation since the tines of a tuning fork are almost always half-period of the cylinder motion. It is clear to see that separated by a distance much smaller than half a wavelength waves propagating in the horizontal and vertical directions of the sound emitted, which means that interference effects have opposite phase, and that the waves completely cancel along lines 45° from the horizontal. should be noticed only at significant distances from the fork 7 A similar sound field is produced when four identical om- tines. Sillitto has shown that close to the fork it is path- nidirectional sources are placed in a lateral quadrupole ar- length-dependent amplitude differences which determine the rangement as shown in Fig. 4͑a͒. Such an arrangement of sound field and that path-length-dependent phase differences sources may be effectively demonstrated by passing a low only become dominant at large distances from the fork. frequency signal through four small boxed loudspeakers with The goals of this paper are to address some of the miscon- opposite polarities.13 The expression for the complex sound ceptions concerning the sound field radiated by a vibrating pressure amplitude produced by a lateral quadrupole may be tuning fork, to discuss the quadrupole nature of the tuning derived as14,15 fork sound field, and to present experimental measurements A 3 i3k of the near-field and far-field radiated patterns. While pri- ͑ ␪͒ϭ ͩ Ϫ 2Ϫ ͪ ␪ ␪ ͑ ͒ p r, 2 k sin cos , 2 mary attention will focus on the sound field produced by the r r r principal mode of the tuning fork, as shown in Fig. 1͑a͒, where A is an amplitude factor which depends on the size, radiation patterns from other less frequently observed vibra- strength, and frequency of the quadrupole source. The pres- tional modes will also be discussed. ence of the ‘‘i’’ in the third term in parentheses indicates that 1139 Am. J. Phys. 68 ͑12͒, December 2000 http://ojps.aip.org/ajp/ © 2000 American Association of Physics Teachers 1139 Fig. 3. Frames from an animated GIF movie ͑Ref. 12͒ animating the sound field produced by an oscillating cylinder according to Eq. ͑1͒. Fig. 1. ͑a͒ Principal mode of a tuning fork. ͑b͒ End view of a tuning fork showing regions of loud and quiet. III. THE TUNING FORK AS A LINEAR QUADRUPOLE this term is 90° out of phase from the other terms. The vari- When a tuning fork vibrates in its fundamental mode, the ϭ ␲ ␭ able k is the wave number (k 2 / ) and r is the distance to tines oscillate symmetrically in the plane of the fork, as the observer. The expression in Eq. ͑2͒ is valid for all dis- shown in Fig. 1͑a͒. Each individual tine might be modeled tances r. At large distances r ͑termed the far field͒ the pres- by a dipole source,17,18 much like an unbaffled loudspeaker19 sure amplitude may be approximated by and a transversely oscillating sphere14 are treated as a dipole Ak2 sources. Dipole sources are discussed further in Sec. V. p͑r,␪͒ϭ sin ␪ cos ␪. ͑3͒ A combination of two dipole sources with opposite phase, r such that the dipole axes lie along the same line, is called a ͑ ͒ ͑ ͒ linear, or longitudinal quadrupole source. The source distri- The angular dependence is the same for Eqs. 2 and 3 . ͑ ͒ Moving from near field to far field has no effect on the an- bution for a linear quadrupole is shown in Fig. 5 a . The exact expression for the pressure field radiated by a linear gular dependence of the directivity pattern. 14,15 Figure 4͑b͒ shows a polar plot of the directivity pattern for quadrupole may be derived as a lateral quadrupole source. For this and all following plots, A ik 1 k2 k2 the pressure amplitude is plotted on a logarithmic scale, with p͑r,␪͒ϭ ͫ͑1Ϫ3 cos2 ␪͒ͩ Ϫ ϩ ͪ Ϫ ͬ. ͑4͒ r r r2 3 3 units of decibels. In addition, all plots have been normalized to the maximum value, as is the accepted practice for direc- The result by Sillitto7 gives an equivalent expression in terms tivity plots.16 The directivity plot shows that the lateral quad- of Legendre polynomials and spherical Bessel functions. rupole pressure field exhibits four directions where sound is Figure 5͑b͒ is a polar plot showing the directivity pattern for radiated very well alternating with four directions in which a longitudinal quadrupole with an observer distance r no sound is radiated. This directivity pattern matches nearly ϭ0.05 m from a 426-Hz source, so that krϭ0.39. The prod- exactly the sound field predicted by the cylindrical source as uct kr is typically used to define the boundary between the shown in Fig. 3. near field and far field of a source. As a general rule of A lateral quadrupole source model has been used to de- thumb, if krϽ1 the observer is in the near field, and if kr 3,8 scribe the sound field of the tuning fork. While this might Ͼ1 the observer is in the far field. appear to explain what one hears in the near field of a tuning The near-field directivity pattern in Fig. 5͑b͒ matches what fork, there are several problems. First, this model does not is heard close to a tuning fork. There are four maxima, two explain why one hears only two maxima and minima when in the plane of the fork and two perpendicular. However, the the fork is held at arm’s length from the ear.
Load more

Recommended publications
  • Sound Sensor Experiment Guide
    Sound Sensor Experiment Guide Sound Sensor Introduction: Part of the Eisco series of hand held sensors, the sound sensor allows students to record and graph data in experiments on the go. This sensor has two modes of operation. In slow mode it can be used to measure sound-pressure level in decibels. In fast mode it can display waveforms of different sound sources such as tuning forks and wind-chimes so that period and frequency can be determined. With two sound sensors, the velocity of propagation of sound in various media could be determined by timing a pulse travelling between them. The sound sensor is located in a plastic box accessible to the atmosphere via a hole in its side. Sensor Specs: Range: 0 - 110 dB | 0.1 dB resolution | 100 max sample rate Activity – Viewing Sound Waves with a Tuning Fork General Background: Sound waves when transmitted through gases, such as air, travel as longitudinal waves. Longitudinal waves are sometimes also called compression waves as they are waves of alternating compression and rarefaction of the intermediary travel medium. The sound is carried by regions of alternating pressure deviations from the equilibrium pressure. The range of frequencies that are audible by human ears is about 20 – 20,000 Hz. Sounds that have a single pitch have a repeating waveform of a single frequency. The tuning forks used in this activity have frequencies around 400 Hz, thus the period of the compression wave (the duration of one cycle of the wave) that carries the sound is about 2.5 seconds in duration, and has a wavelength of 66 cm.
    [Show full text]
  • Fftuner Basic Instructions. (For Chrome Or Firefox, Not
    FFTuner basic instructions. (for Chrome or Firefox, not IE) A) Overview B) Graphical User Interface elements defined C) Measuring inharmonicity of a string D) Demonstration of just and equal temperament scales E) Basic tuning sequence F) Tuning hardware and techniques G) Guitars H) Drums I) Disclaimer A) Overview Why FFTuner (piano)? There are many excellent piano-tuning applications available (both for free and for charge). This one is designed to also demonstrate a little music theory (and physics for the ‘engineer’ in all of us). It displays and helps interpret the full audio spectra produced when striking a piano key, including its harmonics. Since it does not lock in on the primary note struck (like many other tuners do), you can tune the interval between two keys by examining the spectral regions where their harmonics should overlap in frequency. You can also clearly see (and measure) the inharmonicity driving ‘stretch’ tuning (where the spacing of real-string harmonics is not constant, but increases with higher harmonics). The tuning sequence described here effectively incorporates your piano’s specific inharmonicity directly, key by key, (and makes it visually clear why choices have to be made). You can also use a (very) simple calculated stretch if desired. Other tuner apps have pre-defined stretch curves available (or record keys and then algorithmically calculate their own). Some are much more sophisticated indeed! B) Graphical User Interface elements defined A) Complete interface. Green: Fast Fourier Transform of microphone input (linear display in this case) Yellow: Left fundamental and harmonics (dotted lines) up to output frequency (dashed line).
    [Show full text]
  • Tuning Forks As Time Travel Machines: Pitch Standardisation and Historicism for ”Sonic Things”: Special Issue of Sound Studies Fanny Gribenski
    Tuning forks as time travel machines: Pitch standardisation and historicism For ”Sonic Things”: Special issue of Sound Studies Fanny Gribenski To cite this version: Fanny Gribenski. Tuning forks as time travel machines: Pitch standardisation and historicism For ”Sonic Things”: Special issue of Sound Studies. Sound Studies: An Interdisciplinary Journal, Taylor & Francis Online, 2020. hal-03005009 HAL Id: hal-03005009 https://hal.archives-ouvertes.fr/hal-03005009 Submitted on 13 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Tuning forks as time travel machines: Pitch standardisation and historicism Fanny Gribenski CNRS / IRCAM, Paris For “Sonic Things”: Special issue of Sound Studies Biographical note: Fanny Gribenski is a Research Scholar at the Centre National de la Recherche Scientifique and IRCAM, in Paris. She studied musicology and history at the École Normale Supérieure of Lyon, the Paris Conservatory, and the École des hautes études en sciences sociales. She obtained her PhD in 2015 with a dissertation on the history of concert life in nineteenth-century French churches, which served as the basis for her first book, L’Église comme lieu de concert. Pratiques musicales et usages de l’espace (1830– 1905) (Arles: Actes Sud / Palazzetto Bru Zane, 2019).
    [Show full text]
  • The Tuning Fork: an Amazing Acoustics Apparatus
    FEATURED ARTICLE The Tuning Fork: An Amazing Acoustics Apparatus Daniel A. Russell It seems like such a simple device: a U-shaped piece of metal and Helmholtz resonators were two of the most impor- with a stem to hold it; a simple mechanical object that, when tant items of equipment in an acoustics laboratory. In 1834, struck lightly, produces a single-frequency pure tone. And Johann Scheibler, a silk manufacturer without a scientific yet, this simple appearance is deceptive because a tuning background, created a tonometer, a set of precisely tuned fork exhibits several complicated vibroacoustic phenomena. resonators (in this case tuning forks, although others used A tuning fork vibrates with several symmetrical and asym- Helmholtz resonators) used to determine the frequency of metrical flexural bending modes; it exhibits the nonlinear another sound, essentially a mechanical frequency ana- phenomenon of integer harmonics for large-amplitude lyzer. Scheibler’s tonometer consisted of 56 tuning forks, displacements; and the stem oscillates at the octave of the spanning the octave from A3 220 Hz to A4 440 Hz in steps fundamental frequency of the tines even though the tines of 4 Hz (Helmholtz, 1885, p. 441); he achieved this accu- have no octave component. A tuning fork radiates sound as racy by modifying each fork until it produced exactly 4 a linear quadrupole source, with a distinct transition from beats per second with the preceding fork in the set. At the a complicated near-field to a simpler far-field radiation pat- 1876 Philadelphia Centennial Exposition, Rudolph Koenig, tern. This transition from near field to far field can be seen the premier manufacturer of acoustics apparatus during in the directivity patterns, time-averaged vector intensity, the second half of the nineteenth century, displayed his and the phase relationship between pressure and particle Grand Tonometer with 692 precision tuning forks ranging velocity.
    [Show full text]
  • Good Vibrations (Part 1 of 2): [Adapted from NASA’S Museum in a Box]
    National Aeronautics and Space Administration Good Vibrations (Part 1 of 2): [Adapted from NASA’s Museum in a Box] What is it? The transfer of energy from one material to another can be measured in different ways. One that you may not initially think of is sound. Sound can be good, as it allows us to communicate and interact with our surroundings, but sound can also cause disturbance. For example, aircraft noise can be quite loud and cause disturbance in neighborhoods. Scientists and engineers are working hard to reduce these sounds in different ways. In this activity, students will interact with tuning forks to learn about sound. This activity discusses topics related to National Science Education Standards: 4-PS4-3: Generate and compare multiple solutions that use patterns to transfer information. - This activity uses two different models to “see” sound waves, and covers discussions of the transfer of information from one material to another through waves. Materials (per team of 4 to 8 students): Equipment, provided by NASA: - Set of 4 Tuning Forks - Ping pong ball with attached string Equipment, not provided by NASA: - Container of Water (plastic food storage container would work well) - Soft item for activating tuning forks (book spine works well) Materials (per student): Printables: - Tuning Fork Worksheet Artifact included in this kit: - Fluid Mechanics Lab “Dimple Car” and Information Sheet Recommended Speakers from Ames: Please note that our Speakers Bureau program is voluntary and we cannot guarantee the availability of any speaker. To request a speaker, please visit http://speakers.grc.nasa.gov. www.nasa.gov 1 Dean Kontinos (Hypervelocity Air and Space Vehicles) Ernie Fretter (Arc-Jet, Re-entry Materials) Mark Mallinson (Space, Satellites, Moon, Shuttle Technology) Set-Up Recommendations: - Prepare copies of the Tuning Fork Worksheet.
    [Show full text]
  • Tuning the Harp with a Tuner and By
    TUNING THE HARP WITH A TUNER and TUNING BY EAR Courtesy of and by: Elizabeth Volpé Bligh www.elizabethvolpebligh.com Principal Harp, Retired, Vancouver Symphony Harp Faculty, VSOI, VSO School of Music Adjunct Professor, UBC School of Music, President, West Coast Harp Society-AHS BC Chapter I sometimes make the mistake of assuming that everyone knows how to use an electronic tuner, or to tune by ear. There is some misinformation on the Internet, so don't believe everything you see on this subject. I saw one video that said to tune with all the pedals in the natural position (don't do that)! I have articles on my web site about this subject and others. Harp Column magazine, May’s 2020 has articles on tuning and recommendations of tuning apps. https://harpcolumn.com/blog/top-apps-for-tuning/ Tune your harp every day. The harp will stay in tune better, and your tuning skills will improve. Always tune with pedals in the flat position and the discs unengaged. On a lever harp, the levers should be unengaged. This means that when you are tuning a C flat, the tuner will read its enharmonic note, "B". The F flat will read as "E". Some tuners read accidental notes only as sharps or flats, so be aware of the enharmonic names of the notes you are tuning, i.e. E flat = D#, A flat = G#. Most North American harpists tune their A in the range from 440 to 442. Check the tuner's calibration every time you use it, in case you have accidentally pressed the calibration button and it has gone higher or lower.
    [Show full text]
  • Acoustic Analysis of Used Tuning Forks
    J Int Adv Otol 2017; 13(2): 239-42 • DOI: 10.5152/iao.2017.2745 Original Article Acoustic Analysis of Used Tuning Forks Mustafa Yüksel, Yusuf Kemal Kemaloğlu Department of Audiology, Ankara University School of Medicine, Ankara, Turkey (MY) Department of Otorhinolaryngology, Gazi University School of Medicine, Ankara, Turkey (YKK) Cite this article as: Yüksel M, Kemaloğlu YK. Acoustic Analysis of Used Tuning Forks. J Int Adv Otol 2017; 13: 239-42. OBJECTIVE: In this study, we evaluated used aluminum tuning forks (TFs) for fundamental frequencies (FF), overtones, and decay times. MATERIALS and METHODS: In total, 15 used (1 C1, 11 C2, and 3 C3) and 1 unused (C2) TFs were tuned, and the recorded sound data were analyzed using the Praat sound analysis program. RESULTS: It was found that FFs of the recorded sounds produced by the used C2-TFs presented a high variability from 0.19% to 74.15% from the assumed FFs, whereas this rate was smaller (1.49%) in the used C3-TFs. Further, decay times of the used C2-TFs varied from 5.41 to 40.97 s. CONCLUSION: This study, as the first of its kind in the literature, reported that some of the used aluminum TFs lost their physical properties that are important for clinical TF tests. It could be said that this is a phenomenon related to metal fatigue, which is common in aluminum products due to the cyclic load. KEYWORDS: Tuning forks, aluminum, hearing loss INTRODUCTION Tuning fork (TF) is a device that produces a fundamental frequency (FF) and at least one additional overtone when it is struck.
    [Show full text]
  • SOUND and RESONANCE 2018-2019 VINSE/VSVS Rural
    VANDERBILT STUDENT VOLUNTEERS FOR SCIENCE http://studentorgs.vanderbilt.edu/vsvs SOUND AND RESONANCE 2018-2019 VINSE/VSVS Rural Goal: To introduce students to sound waves, resonance, and the speed of sound. LESSON OUTLINE 1. Wave Demonstration VSVS volunteers demonstrate compressional and transverse waves with a slinky, an air blaster and wave machine. 2. Sound is produced by vibrations. Students spin a hex nut inside an inflated balloon and observe that they can feel the balloon vibrating when there is a sound being produced. 3. Natural Frequency A. Student Activity Students are introduced to resonance by having them listen to the pitches created in tubes of different lengths. 4. Introducing Tuning Forks Students are introduced to tuning forks. They note the frequency and corresponding keynote on each fork. 5. Finding the length of a tube at which resonance is heard Students hit a tuning fork with a mallet and place it at the opening of the shortest of 4 tubes. They listen closely to hear if the volume of the sound has increased. They move the tuning fork to the openings of the other tubes and discover which tube produces resonance. VSVS members will collect the data and write it on the board. The class will learn that longer tubes are needed for the tuning fork with the lower frequency, shorter tubes are needed for the tuning fork with higher frequency and that the same length tube is needed for tuning forks with the same frequency. Optional Students can exchange tuning forks so that they have one that has a different frequency, and repeat the above activity.
    [Show full text]
  • Sound Waves and Beats
    Computer 32 Sound Waves and Beats Sound waves consist of a series of air pressure variations. A Microphone diaphragm records these variations by moving in response to the pressure changes. The diaphragm motion is then converted to an electrical signal. Using a Microphone and a computer interface, you can explore the properties of common sounds. The first property you will measure is the period, or the time for one complete cycle of repetition. Since period is a time measurement, it is usually written as T. The reciprocal of the period (1/T) is called the frequency, f, the number of complete cycles per second. Frequency is measured in hertz (Hz). 1 Hz = 1 s–1. A second property of sound is the amplitude. As the pressure varies, it goes above and below the average pressure in the room. The maximum variation above or below the pressure mid-point is called the amplitude. The amplitude of a sound is closely related to its loudness. When two sound waves overlap, their air pressure variations will combine. For sound waves, this combination is additive. We say that sound follows the principle of linear superposition. Beats are an example of superposition. Two sounds of nearly the same frequency will create a distinctive variation of sound amplitude, which we call beats. You can study this phenomenon with a Microphone, lab interface, and computer. OBJECTIVES Measure the frequency and period of sound waves from tuning forks. Measure the amplitude of sound waves from tuning forks. Observe beats between the sounds of two tuning forks. MATERIALS computer Logger Pro Vernier computer interface 2 tuning forks or electronic keyboard Vernier Microphone Physics with Vernier 32 - 1 Computer 32 PRELIMINARY QUESTIONS 1.
    [Show full text]
  • Large Scan Area High-Speed Atomic Force Microscopy Using a Resonant Scanner B
    REVIEW OF SCIENTIFIC INSTRUMENTS 80, 093707 ͑2009͒ Large scan area high-speed atomic force microscopy using a resonant scanner B. Zhao,1 J. P. Howard-Knight,1 A. D. L. Humphris,2 L. Kailas,1 E. C. Ratcliffe,3 S. J. Foster,3 and J. K. Hobbs1 1Department of Physics and Astronomy and Department of Chemistry, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, United Kingdom 2Infinitesima Ltd., Oxford Center for Innovation, Mill Street, Oxford OX2 0JX, United Kingdom 3Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom ͑Received 22 July 2009; accepted 24 August 2009; published online 22 September 2009͒ A large scan area high-speed scan stage for atomic force microscopy using the resonant oscillation of a quartz bar has been constructed. The sample scanner can be used for high-speed imaging in both air and liquid environments. The well-defined time-position response of the scan stage due to the use of resonance allows highly linearized images to be obtained with a scan size up to 37.5 ␮min 0.7 s. The scanner is demonstrated for imaging highly topographic silicon test samples and a semicrystalline polymer undergoing crystallization in air, while images of a polymer and a living bacteria, S. aureus, are obtained in liquid. © 2009 American Institute of Physics. ͓doi:10.1063/1.3227238͔ I. INTRODUCTION levers, enhancing the scanner system rigidity, and/or increas- ing the feedback bandwidth by using fast electronics and The atomic force microscope ͑AFM͒ is one of the most control methods.
    [Show full text]
  • Speed of Sound in Tuning Fork Metal V Anantha Narayanan Savannah State College, GA, USA and Radha Narayanan Student, Windsor Forest High School, Savannah, GA, USA
    NEW APPROACHES weights of those components, such as the tail itself weight of the tail of the fish will be eliminated. and the linkage members, which are also raised in Through this improvisation it also becomes possible the process and to the force required to to increase the number of elements beyond four and counterbalance the spring loading within the tail explore the eventual limits to the development of the which returns the device to its original state after machine. use. All of these factors give rise in practice to some Note. The Lazyfish is manufactured and distributed loss of efficiency. Further measurements could be by by Bacchanal Limited, Unit 15, Hale Trading made with the spring balance attached at H and K Estate, Lower Church Lane, Tipton, West Midlands in turn to investigate the changes in mechanical DY4 7PQ (tel: 0121 520 4727; fax: 0121 520 7637). advantage which result when the number of elements in the linkage is reduced. Received 22 April 1996, in final form 10 July 1996 If the commercial device is not available then the linkage, which is the essential component for teaching purposes, could be very easily improvised Reference from metal strips such as Meccano. In this case the Sandor B I 1983 Engineering Mechanics: Statics effects of the spring loading in the tail and the and Dynamics (Englewood Cliffs, NJ: Prentice-Hall) Speed of sound in tuning fork metal V Anantha Narayanan Savannah State College, GA, USA and Radha Narayanan Student, Windsor Forest High School, Savannah, GA, USA A procedure to find the speed of sound in tuning Transverse motions of the prongs cause an up and fork metal is described.
    [Show full text]
  • Tuning Fork Basics
    Tuning Fork Basics It’s important never to bang a tuning fork directly on a hard surface, as this could damage the tuning fork. Instead, grasp it firmly at its end but keep your wrist and fingers relaxed. Bend your elbow when holding it. There shouldn't be any tension in your arm. Hold the tuning fork on its side so you're striking only one of the prongs. Tap it against the heel of your hand or a rubber object. It’s made of dense metal, usually steel. Strike the tuning fork prong about one-third of the way from the top. This is important to get the best sound. The "U" shape causes both sides to vibrate and produces a smooth sound wave. Visualizing Waves Tap the tuning fork against the heel of your hand, and look closely at the tips as the fork hums. You'll notice the tips are vibrating very slightly. This is a simple activity, but it clearly demonstrates sound waves in a visible way. Try a variety of tuning forks, and see if you notice any difference in their vibrations. Wave Transfer Sound waves and energy transfer through various materials differently. Have one partner sound a tuning fork and hold it in the air while the other partner walks away until he/she can't hear it any longer. Measure the distance. Strike the tuning fork again and set the vibrating tuning fork carefully on a hard surface like a desk or a chair seat. This acts as a sounding board and amplifies the pitch.
    [Show full text]