Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
Universiti Pendidikan Sultan Idris (UPSI)March 2014DANCING PARTICLES: VISUALISATION OF RESONANCE OF AIR
COLUMN IN MICROGRAVITY ENVIRONMENTANDPERFORMANCE CONFIRMATION OF UNIVERSAL MASSBALANCE USING OPTICAL DETECTION(1)

Shahrul KADRI Ayop*, (2)Mohd Helmy HASHIM, (1)Mohd Ikhwan Hadi YAACOB,(1)

KOK Keng Hon and (1)Ahmad Tarmimi ISMAIL(1)

Sultan Idris University of Education, Perak, MALAYSIA(2)National Space Agency of Malaysia (ANGKASA)
shahrul.kadri@fsmt.upsi.edu.my*

Abstract
We performed two experiments in Asian Student Parabolic Flight 2013 Campaign. The firstexperiment is about the visualization of resonance of air column. We visualised the resonanceof air column using polystyrene beads of 1 mm diameter. When the sound source is tuned at
the correct frequency, the beads are arranged through out the tube, filling the rarefaction partin the column. We compared the resonance profile in normal gravity and microgravity forhorizontal and vertical tubes. Observation showed that the resonance profile is more clearlyvisible in microgravity even at relatively low driven sound intensity. We made post flight
exhibition and conducted simple survey to know public prediction on the resonance profile.
For the second experiment, we test the universal mass balance using optical detection
compared to emf detection we did in Asian Student Parabolic Flight 2013 Campaign. Results
show that variation in gravitational field does not significantly affect the oscillation of a mass
load.

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Experiment 1 : Resonance of Air Column

Objective:

To investigate the profile of resonance of air column in hypergravity,

normal gravity and microgravity.
Introduction
It has been shown that sound resonance in tube can occur at right tube length andsupplied sound frequency [1]. However, detection is done using microphone connected tospectrum analyzer. Students face hard problem to visualize such phenomena since spectrum
analyzer is weird for them even at the university level. To visualize such effect, Kundt’s tube
can be used.

The tube was originally used to determine the mechanical properties of

unknown metal rod and acoustical properties of gases [2]. However, dust or visible particles,
which settle at the base of the tube due to gravity, does not assemble clear representation ofresonance profile.

Sound is a mechanical wave due to the vibration of molecules. Wind instruments suchas trumpet and flute produce sound of different tones when air molecules in the instruments
are tuned and vibrate with maximum amplitude at specific frequencies called harmonics. The
harmonics or resonant frequencies are established when standing waves of air column
matched the boundary conditions of the instrument.

In this project, we would like to observe true resonance profile of air column in tubeat which gravity effect is much reduced. In microgravity, such tube with modified geometry
has been performed in the perspective of art [3]. But to give more insight into scientificimportance of the sound propagation in microgravity, we further extend the profile formationby controlling parameters (i) the frequency of driven sound, (ii) air column orientation and(iii) tube types.

Methodology
We prepared two sets of two tube types, one set for horizontal orientation denoted by
H and the other set for vertical orientation denoted by V, as shown in Figure 1. Two types oftube are tube with closed end denoted by C and tube with open end denoted by O. Therefore,
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we have four tubes in the rack: HC, HO, VC and VO. The other end of the tubes is attachedwith speaker. The tubes are made of cylindrical shaped perspex with 26 mm inner diameterand 36 cm length filled with polystyrene beads. The other end of HO and VO are closed withmesh fabric which allows air to vibrates but restrict bead from going out of the tubes.
Meanwhile the other end of HC and VO are closed with a piece of perspex which cause
molecular displacement node. All tube are connected to 4-channel home-made function
generator. Figure 2 show the real setup of the experimental rack.

VC

VO

Function
Generator

HO
HC

Figure 1

Experiment Arrangement.

Figure 2 Top view of the experimental rack.

Table 1 and 2 shows the information and setting used in this study. The fundamental
frequencies were set at 230 Hz and 467 Hz based on the guided formulae for CO and CC
tubes respectively. The air molecules are highly dense at the closed ends where aircompression is formed (black band). Meanwhile, the available space in air rarefaction area
will be complementarily filled with beads (white band). Therefore, the area of dancing beads
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Universiti Pendidikan Sultan Idris (UPSI)March 2014

represents the rarefaction part of the resonance profile.

Meanwhile for the second harmonics, 690 Hz and 934 Hz were set for CO and CC
tubes respectively. Compared to the first harmonics, 2 areas (white bands) of highly
preferable for bead to settle is available in both tubes.

Table 1 Information and setting used for air column at fundamental frequency.
FormulaAir molecular distribution at

Fundamental

Tuberesonance

Frequency (Hz)Type

(black colour represent high air
density)

CO

open
end

closed
end

230

CC

closedend

closedend

467* v = 343.4m/s at 20oC, atm pressure, L = 36 cm, d = 26 mm, n = 1

Table 2 Information and setting used for air column at second harmonic.
FormulaAir molecular distribution at

SecondTuberesonance

Harmonic Hz)

Type(black colour represent high air
density)

CO

open
end

CC

closedend

closedend

closedend* v = 343.4m/s at 20oC, atm pressure, L = 36 cm, d = 26 mm, n = 2

4

690

934

Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
Universiti Pendidikan Sultan Idris (UPSI)March 2014

Result and Discussions
All tubes are set at the designated harmonic frequencies 1 minute before each cycle ofparabolic parabolic flight. Four gravity environments were simulated in the following
sequence, hypergravity 1 (HG1), microgravity (0G), hypergravity 2 (HG1) and normal
gravity (1G). The first three gravity conditions occurred in about 20s each. The gravitational
strenght from the highest to lowest are in the following order : HG1 (~2G), HG2 (~1.5G) 1G
and 0G.

Horizontal tubes at fundamental frequency
Table 3 shows the resonance profile of horizontal air column at fundamental
frequency in different gravity environments. The sound intensity was set at 35%, 40%, 45%
and 50% which has to be calibrated further post-flight to get the absolute value of acoustic
intensity. The mountain-liked profiles were observed in HG1 and 1G where the profile. The
beads assembled at the air displacement nodes and became clearer at lower gravity forming
pattern of striations. The beads were not just statically distributed along the tube but agitatedaccordingly, thus called dancing particles. In microgravity, plates of beads were formed
where the number of plates is higher at the air displacement nodes. Beads lost their weight
and were able to fill in the gap of rarefaction part of the air column uniformly. However,some beads remained at the tube base due to electrostatic effect.
In HG, the striations become clear at higher sound intensity. In both 1G and 0G,
beads move away from speakers in both tubes as higher intensity of sound is driven. In thiscondition, resonant profiles collapsed and the striations were no longer static but moving
between air displacement nodes away from speakers.
Vertical tubes at fundamental frequency
Table 5 (left) shows the resonance profile of vertical air column at fundamental
frequency in different gravity environments. At HG, and 1G, the beads are hardly moved
since the weights of the beads were more dominant compared to the established acousticalforce in resonance. We expected the profile observation would be comparable between
vertical and horizontal tube in 0G. However, the beads were hardly moved upward. Rings ofbead were seen crawling upward in VC tube while small number of beads floated in VO tube.
We expect tht the condition of HG before 0G caused the beads to accumulate near speakerthus the air column system need more time to push beads upward. Compared to VO tube, the5Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
Universiti Pendidikan Sultan Idris (UPSI)March 2014

air displacement antinode of VC tube is at the center of the tube, which is closer to the
speaker. Thus the rarefaction part is able pull the beads upward. The rings formation is due tothe electrostatic attraction between beads and tube.

Horizontal tubes at second harmonics
Table 4 shows the resonance profile of horizontal air column at second harmonic indifferent gravity environments and sound intensity. Two areas of bead accumulation wereobserved in all settings.

Vertical tubes at second harmonics
Table 5 (left) shows the resonance profile of vertical air column at second harmonics
in different gravity environments. Here, no clear resonance profiles were observable. Small
amount of beads were moving upward in rings formation in microgravity environment

From this experiment, we can see that the formed resonance profile does not assemble
the molecular distribution shown in Table 1 and 2. Striations of beads were formed in rings(vertical tube in microgravity), mountain like walls (horizontal tube in 1G) and plates(horizontal tube 0G). The striations pattern observed in horizontal tube in 1G, which showedresonance profile, has been reported and analyzed in prior work [2, 4, 5], They weresuggested to be originated from the vortex formation. As sound intensity is increased, thestriations were no longer stationary at air molecular nodes, but alternately build-up andcollapse while moving away from speaker.

Quantitative analysis is still in progress to understand the striations formations. In
microgravity, striation plates were easily established even at low driven sound intensity. Even
though the plates were hardly seen in vertical tube, the pattern is can be achieved if they areplace in long microgravity condition. This finding may find application in particle separation
technology where the separation is better in microgravity in precisely controlled condition.

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Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
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Table 3

March 2014

First Harmonic: Upper tube (CC: 467 Hz) and lower tube (CO: 934 Hz)
HG
1G
0G

#1
35%
#2
F1
40%
#3
45%

#4
50%

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Table 4Harmonic: Upper tube (CC : 934 Hz) and lower tube (CO 690 Hz)
HG1
1G
0G

#5
35%

#6
40%

#7

March 2014

Not Available

45%

#8
50%

#9
80%
#10
80%

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Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
Universiti Pendidikan Sultan Idris (UPSI)

Table 5

March 2014

Vertical tubes: For each snapshot, CC is on the left and CO is on the right.
First Harmonic:
CC at 467 Hz and CO at 934 Hz
HG
1G
0G

Second Harmonic:
CC at 934Hz and CO at 690 Hz
HG
1G
0G

#1
35%

#5
35%

#2
40%

#6
40%

#3
45%

#7
45%

#4
50%

#8
50%

9

Not
Available

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Universiti Pendidikan Sultan Idris (UPSI)

#9
80%

#10
80%

10

March 2014

Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
Universiti Pendidikan Sultan Idris (UPSI)March 2014

Conclusion
Resonance profile using polystyrene in vertical tube can be clearly established at relatively
low sound intensity in microgravity. The observed bead distribution represents compression
and rarefaction part of the resonance profile of an air column. The beads agitated mostly inthe rarefaction part to fill in the gap between air. Due to slow response time, it is difficult toachieve the resonance profile for vertical tube during short microgravity period in parabolic
flight. However, the formation of bead rings shows an interesting effect of electrostatic force
between beads and tubes.

Education OutreachWe participated several post-flight exhibition to disseminated information and experience
gain during the parabolic flight campaign. We devised a simple survey to get public
expectation about the resonance profile of an air column in microgravity. First we explained
and made demonstration of the formation of resonance profile by tuning the speaker at thecorrect frequency using our experimental rack. Most of our visitors were surprised to observe
the accumulation of the beads at particular spot and beads were dancing. Then, explanation is
given according to question asked by visitors. Finally, they were given a sweet. They wereasked to predict the resonance profile in the outer by putting the wrap of the sweet into theiroption (Figure 4).

Figure 5 shows response from public collected in February 2014. The correct option
is E as selected by 15.3% of the respondents. One forth of them chose F for their prediction.
The rest were divided into 5 other options with close percentages. It is very interesting to see
majority of them chose F where beads are randomly distributed. We expected that the visitor
related no-gravity outer space to floatation of object. They did not notice the acoustical force
is still in action hold beads at particular positions. The survey, even though is very simple,
give us an insight about public understanding about gravity.

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Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
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Figure 3

March 2014

Mr Kok is preparing booth for exhibition. (left). High school students visitedthe booth. (right)

Figure 4

Visitors were asked to vote their prediction, which six options are available(left). Mr Kok shows responses from visitors.

12Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
Universiti Pendidikan Sultan Idris (UPSI)

Figure 5 Public response

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March 2014

Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
Universiti Pendidikan Sultan Idris (UPSI)March 2014

Experiment 2 : Universal Mass Balance (UMB)

Objective: To confirm the measurement of mass using UMB with optical detection is

independent to gravitational strength.
Introduction
Mass measurement is an important procedure in scientific research as well as in daily life. On
earth, mass balances are designed based on the earth gravitational attraction on the object
being measured. These devices are useless at the location where gravitational strength is not
the same value as earth gravity. We confirmed that mass measurement using a pair of springis independent on gravitational field within experimental errors [6, 7] using electromotive
force (emf) detection method. This time, we use optical detection method to record theoscillation of a mass.

Methodology

Figure 6

The mass position on the ground.

A oscillating mass consisted of a piece of 4 cm height Perspex and copper rod is attached
between a double pair springs and a spring of 5.14 N/m. The mass is 7.672 g (as measured on
the ground). The double pair springs was used to constraint the mass oscillation in one
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dimension up and down. On the ground, the upper part stretched 11.0 cm and the lower partstretched 17. 5 cm as shown in Figure 6.

The oscillation is detected using optical detection method. A infrared light emitting
diod (LED) is aligned to infrared photodiode. One side of the Perspex is stick with an opaquetape. Each time the mass passing trough the detector, a pulse is send to microcontroller. One
cycle of oscillation is calculated from the time taken between two pulses. The microcontroller
is set so that it calculates the average frequency of 8 complete cycles. The measurement isperformed by pulling the mass using a string to set the mass into oscillation.

ResultData taken during parabolic flight on the second day is tabulated in Table 6. Some data could
not be recorded due to technical difficulties faced by our parabonaut. Oscillation frequency ofthe load on the ground is 1575 ± 1 Hz for four repeated measurements. From the averagevalues, oscillation frequency is independent of gravitational strength within 0.2% error.
Therefore, our alternative optical detection shows good potential for the measurement ofmass based on mechanical oscillation of a load.
Table 6 : Data taken during parabolic flight on the second day (December 26th, 2013).
Cycle Number

3

5

7

9

Average

HG1

NA1575 Hz

NA

1576 Hz

1576 ± 1 Hz

0G1

1576 Hz

1575 Hz

1580 Hz

1575 Hz

1575 ± 2 Hz

HG2

NA

1575

NA

1576 Hz

1576 ± 1 Hz

Conclusion
We measured the mass of 7.672 g load using pair spring and optical detection method. The
result shows that the oscillation frequency of a given load is independent of gravitational
strength within 2% experimental error.

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Malaysia Parabolic Flight 2013 Programme -Comprehensive Report
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Acknowledgments
We would like to acknowledge the following agencies that support this project: Universiti
Pendidikan Sultan Idris (UPSI), Ministry of Science, Technology and Innovation (MOSTI),
National Space Agency of Malaysia (ANGKASA), Japan Aerospace and Exploration Agency(JAXA) and Diamond Air Service (DAS). This project is partly supported by UPSI grantcode 2013-0172-102-03 and 2012-0108-102-03. We thank Prof. Rosly for his guidance
throughout the experiment preparation.

References[1] Kadri, S., Jaafar, R., Adli, W. Z., & Nazihah, A. (2013). Physics demonstration of soundwaves using Visual Analyser. Latin-American Journal of Physics Education, 7(1).
[2] Kundt, A. (1866). "Ueber eine neue Art Akustischer Staubfiguren und über die
Anwendung derselben zur Bestimmung der Shallgeschwindigkeit in festen Körpern undGasen". Annalen der Physik (Leipzig: J. C. Poggendorff) 127 (4): p.497–523.
[3] Namba, et. al (2006). Experiment for Sculpture Formed Sound Wave. J. Jpn. Soc.
Microgravity Appl., 23(4).
[4] Hutchisson, E., & Morgan, F. B. (1931). An experimental study of Kundt's tube dust
figures. Physical Review, 37(9), 1155.
[5] Carman, R. A. (1955). Kundt Tube Dust Striations. American Journal of Physics, 23, 505.
[6] Kadri, S., Aziz, W., Suhaila, W. N., Hashim, M. H., Jaafar, R., & Yaacob, M. I. H. (2013).
Mechanical Efficiency of a Mass-Spring System in Hypergravity, Normal Gravity andMicrogravity. Applied Mechanics and Materials, 390, 261-265.
[7] Kadri, S., Daud, M., Nazihah, A., Hashim, M. H., Rosli, J., Asillam, M. F., & Nurlisman,
Z. K. D. (2013). Simple Design of a Gravity-Independent Mass Balance. Applied Mechanics
and Materials, 390, 637-640.

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