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Download Physics of Music PHY103 Worksheet #3 Set up for Train Whistle Lab
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Physics of Music PHY103 Worksheet #3 Set up for Train Whistle Lab 1) Relation between frequency and length of a whistle. The relationship between length (L) and frequency (f) of the fundamental mode of an open tube of air is given by the following formula: L 1 f Supposing you blow a whistle that is 21 cm long and you hear the note F4 at 349.23 Hz. You then saw off 2.3 cm off the end of the whistle so the length is now 18.7 cm. What frequency do you expect that the whistle will blow? What note does this correspond to? 2) Octaves and frequency. a) The frequency of middle C is 261.63Hz. This is called C4 because it is the 4th octave on the piano. What is the frequency of the C one octave lower or C3? Frequencies of Notes in the Tempered Scale 4th octave Note Frequency (Hz) C4 261.63 C# (D♭)4 277.18 D4 D# (E♭)4 E4 F4 F#(G♭)4 G4 293.66 311.13 329.63 349.23 369.99 392.00 G#(A♭)4 415.30 A4 A#(B♭)4 440.00 466.16 B4 493.88 To predict the notes in the octave above this multiple the above frequencies by two. To predict the notes in the octave below this, divide the above frequencies by two. b) What is the frequency of A#5 or the A# one octave above concert A (440 Hz)?
