PASCO WA-9867, Instruction Manual

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Model No. WA-9867 Experiment 2: Teachers’ Notes–Resonance Tubes
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Experiment 2:
Teachers’ Notes–Resonance Tubes
If you have twirlable Sound Tubes (SE-8692), trim them to slightly different lengths so they play
different notes.
Part I
Slope = 8570 cm/s = 85.7 m/s
v = 4 (85.7 m/s) = 343 m/s
v = 331 m/s + (0.6)(25 °C) = 346 m/s. (The scale factor in this formula should have units of K
-1
.
That detail has been omitted for simplicity.)
% Deviation = -1%
Tube Diameter = 14.5 cm
End Effect = 0.3(14.5) = 4.4 cm, as compared to the y-intercept, which is 6.7 cm. Still, this shows
the concept that the wave extends outside the end of the tube by several centimeters. Ask students
to consider the uncertainty of the best-fit line’s y-intercept.
Further investigations:
f = 230 Hz
Position of first node = 104 cm
Position of second node = 28 cm
λ
= 2 (104 cm - 28 cm) = 152 cm
v =
λ
f = (1.52 m)(230 Hz) =350 m/s
% Deviation = 1%
L
(cm)
f
(Hz)
1/ f
(1/Hz)
120 68 0.015
110 74 0.014
100 80 0.013
90 88 0.011
80 98 0.010
70 111 0.0090
60 128 0.0078
50 155 0.0065