my AOK for human/natural sciences

1. Jetro Pirasmepulkul
The Truth Behind Head-heavy Badminton Rackets
In the game of badminton, often regarded as the fastest racket sport, the
“smash” is often its most notable and exciting shot. This offensive stroke is
utilized more than ever since the introduction of the new “rally-point system”
(volleyball-style counting), resulting in a shift in game strategy. Since the game is
now shorter in length, players evolve to play a much more aggressive game by
focusing primarily on fast and powerful attacking strategies to quickly gain
points from the opponent’s weaker returns, rather than the conventional
strategy to slowly expose the other’s weaknesses from longer rallies.
This is why nowadays, major badminton racket companies such Yonex,
Victor, and Li-ningfocus a lot on advertising how their new “offensive play-style”
racket will bring the user victory because of the powerful shots it generates1.
Please refer to Figure 1 for an example of Yonex’s newest racket and the related
advertisement campaign. What makes these rackets so “powerful” to use, per
say, is due primarily to the weight on the frame, known as head heaviness.
Therefore, players often believe that since a powerful smash is the advantageous
shot, in order to get the most powerful smash, a head heavy racket has to be
used.
But is this simple logic really true? Would a more head-heavy racket
actually deliver a more powerful smash? This experiment aims to investigate the
truth behind the current trend in racket development and advertisement that
greater racket head heaviness produces greater shuttlecock speed, as compared
to head light ones.
The theory that models this relationship is momentum. According to the
equation of momentum
P=mv equation 1
The momentum (P) equals the mass (m) times velocity (v). According to
the law of conservation of energy, in a closed system that is not affected by
external forces,then the momentum of the racket will be equal to the momentum
of the shuttlecock. This is seen in the equation:
Vshuttlecock = (m racket v racket) /m shuttlecock equation 2
This equation explains that all of the kinetic energy will be transferred
from the racket to the shuttle.In this experiment, the racket will be swung at the
maximum possible velocity, and to achieve so, a full body jump smash shot will
be used. If vr is kept as a constant and msstays the same, then mr is the
independent variable. Therefore, the equation should be linear in the form
y=mx+b, as mass on head increases, the velocity of shuttlecock will increase. To
replicate a closed system, the experiment will be conducted in the Rajendra hall
without air conditioning fan on.

2. Figure 1- A 2012 advertisement
campaign of Yonex’s newest head-heavy
based rackest- The Voltric Z-force. This 1
technique is commonly seen in most
top-of-line rackets in the market today,
that head heavy rackets are for offensive
play style.
http://www.yonex.com/z/
Design:
Variable Measurement/control
Independent Head-heaviness of racket
Varied by clay and duct tape
added to top of frame
Dependent Shuttlecock speed
Controlled Camera used to record and its
settings
Location and lighting
Shuttlecock- same tube, same
brand (Yimnex)
Racket used (refer to constants
below)
Stroke: Smash
Smash technique: Full rotation,
full body jump smash in most
professional manner. Swing
racket with fastest possible arm
speed.
Person smashing (Jetro
Pirasmepulkul)
Credibility: .
Constants:
The racket used in this experiment is Jetro’s main racket, as used
throughout the season.
Head Racket: Figure 2- The racket is the
250mm constant of this experiment.
These are the specifications of
this racket:
Shaft+ Cap: Brand: Victor
260mm Model: Meteor X80
Shaft: Stiffness: Extra stiff 5/5
Grip: Head Heaviness: Head heavy
216mm
165mm 4/5
Grommet holes: 80
1 Strings: YonexNanogy 95
Tension: 24 lbs all around.
Grip: 1 layer YonexSupergrap
as over grip.

3. Methods
Mel Jetro
Spot Lights Siripong
Figure 2- Top view diagram of the experimental set up. The arrow on the court represents
the direction of Jetro’s jump smash.
Figure 3- A photograph showing a side view of the apparatus set up on Jetro’s
side of the court. Note that the spotlights are at the same height as the apex of
Jetro’s swing. Extra lighting is needed for a better video recording.

4. Procedures
After setting up the court according to the diagram, the following procedures
were conducted:
1. Both players stretch, rally, and practice smashing until all muscles are
loose and ready to play at peak performance.
2. When ready, a new shuttlecock is weighted. Jetro drinks a sip of water to
keep hydrated.
3. Siripong Fong (Camera man) stands atop table, holding camera still and
records.
4. Mel (Shuttlecock feeder) does a high under arm forehand serve to the
center of the court.
5. Jetro jump smashes straight to Mel (no cross-court). Mel does not receive.
6. Repeat steps 4-5 six times. Save video. (although only three trials will be
used in data processing, six trials are made to avoid error).
7. Measure mass of used shuttlecock. Jetro hydrates himself.
8. A strip of clay is massed, flattened to the top of the racket’s frame directly
on the center, no more than 10 cm long. Duct tape is used to secure the
clay to the frame.
9. Measure new weight of racket.
10. Both players do a brief warm up period and practice smashing to get
accustomed to new racket momentum. This is to avoid mishits.
11. Repeat steps 2-7 for new racket weight.
12. Take out the duct tape from racket frame and repeat steps 8-11, for a total
of 6 different racket weights.
Data Processing
Table 1- Raw Data of Racket Head Mass and Velocity Recorded through
Apparatus
Mass Velocity recorded without conversion
Total Mass
Added to (m/s)
of Racket
Head
(±0.01g) T1 T2 T3 Average
(±0.01g)
0.00 94.82 1.80 2.01 1.86 1.89
1.62 96.45 2.41 2.49 2.39 2.43
2.65 97.48 2.62 2.58 2.80 2.67
3.44 98.26 2.73 2.77 2.72 2.74
5.49 100.31 2.81 2.78 2.71 2.77
9.59 104.41 1.66 1.60 1.52 1.59

5. Figure 4- This is a sample graph
for Trial 1 of mass 2.65 ±0.01g. The
green line on the high-speed camera
video shot is the “reference length”,
in the distance that the shuttlecock
travels in the video is based upon.
This is the length from the T-joint to
the bottom of the racket grip cap, measuring a total of 0.252 m. The perpendicular
yellow lines are the set origin so that the horizontal yellow line is parallel to the
path of the shuttlecock in order so that the velocity can be determined. In the
Loggerpro graph, the red dots correspond to the blue dots in the video frame.
The blue dots mark the path of the shuttle over 7 frames while each red dot
represents the shuttlecock’s position at the corresponding time. The velocity of
the shuttlecock is determined using the slope of the linear regression line over
the 7 red dots.
Table 2- Processed Data with Converted Shuttlecock Velocity
Mass Added to
Head (±0.01g) Average Velocity
(km/h)
0.00 220
1.62 290
2.65 310
3.44 330
5.49 330
9.59 190
The average velocities in this table are converted from the velocity recorded by
the high-speed camera. This was done by multiplying the average velocity in the
table above by 3.6 to convert m/s to km/h, then by 33.3 to account for the
difference in frame rates of the video watched at 30 frames per second (fps) and
the rate at which the video was actually taken at 1000fps. Thus, the velocity in
this table in km/h is the actual velocity of the shuttlecock produced in the
experiment.

6. Figure 5- This graph shows the relationship between increasing racket head
weight and the velocity of the shuttlecock produced from the jump smash.
According to the first five data points, this relationship is best represented as a
Natural Exponential relationship, where there is an asymptote to the velocity
of the shuttlecock as the muscle reaches its maximum contraction speed. The
sixth data point is excluded from the curve fit because its value is significantly
different from others, and therefore, an outlier.
Conclusion
According to the graph in Figure 5 above, this experiment shows that as the mass
added to the racket head increases, the velocity of the shuttlecock produced by a
jump smash increases as a Natural Exponential graph as well. This relationship is
modeled by equation
-118.8 +/- 10.48 ^(-0.5804 +/- 0.1264m) +338.4 +/- 9.002
A
and Evaluation
Fatigue
Shuttle feather- different angle, different shuttle has different
Position and method of hit
Distribution of weight added- clay is not totally flat, adding to air resistance, too
much weight causes too much flex in racket. Too much flex makes the racket feel
like its going to snap, or cannot be
Personal conscience to protect racket (snap underload)

7. Concluding
 State and explain a conclusion, including uncertainties, that is supported by your data. Your
conclusion should directly answer your research question. Do not use the word “prove”, use
"show" or "support" instead. Nothing is ever proven in science. Your results only support
your conclusions.
 If possible, include an equation, with uncertainties, showing the relationship between the
research question variables.
 Compare the results with literature values, including percent error, if appropriate.
 Discuss any other findings of importance (beyond the research question).
 State and explain the limits of applicability of your conclusions. What situations can your
conclusion be legitimately applied to?
 Justify any data that was dropped during the analysis.
Evaluating procedures
You should discuss 3-4 of the major weaknesses and limitations of your investigation. Two
“weaknesses” to avoid including are “Not enough time” (If you needed more time, you should have
continued outside of class.) and “Human error” (Science is always done by humans, so “human error”
is meaningless. Be specific; explain what exact “error” the humans committed.)
Here are some ideas of what to think about when identifying the major weaknesses.
 Check each step of the procedure to determine if it was imprecise, and HOW the data could
have been affected.
 Discuss any weakness in the control of important variables.
 Discuss any weakness in the range, timing, or frequency of measurement.
 Comment on the precision and accuracy of measurements.
 State how any of the following might have affected the data/results:
o initial conditions of the specimens or materials
o human handling of the specimens or materials (including how the process of
measuring might have influenced the investigation)
o time for stabilizing system or between when measurements were taken
Improving the investigation
For each weakness mentioned above, you should suggest a realistic modification to the experimental
technique to improve the reliability of the results.
Finally, you should include suggestions for an investigation that would continue from and build on this
investigation.