Director's Cut: Trial 0

Director's Cut: Trial 0

Date: 4 July 2012

Time: 3pm-5pm
Room temperature: 27°C

Weather: Sunny 

I tried to conduct my (hoped) final experiment today in school and said hopes crashed, burned and ran off to find mummy. There won't be multiple posts of procedures/results/etc because I didn't even collect all the data.

1. There were supposed to be 28 GRBs, each and every one of a different size and shape made, measured, cooked and measured again. If possible, multiple duplicates, but that could come later. Of course it devolved into a mess.
2. I was using unfamiliar equipment in an unfamiliar lab. While the good lighting (which you can see from the photos) and the conveniently placed sink and work bench was much appreciated, unfamiliar is still disorienting.
3. Because I was using school property, there was a time limit and plenty of people watching. It doesn't sound like much, but I swear you get much more stressed about how your GRBs are doing when people are walking by asking if they could eat them.
4.  I got four phone calls, each striking just when I'd settled the last, washed my hands and picked up the dough again. So, very, popular.
5.    The hotplate at school took 40 minutes to boil the water, then it gave up and stayed at 80 °C the moment the GRB were introduced. So, first batch of results nigh unusable-but very attractive-to-fellow-experimenters-anyway-reminders of failure.
6. Thanks to Mr Ali and Mr Ooi, second batch was done on two bunsen burners, but then you had to scramble to keep the water at just the right temperature so that it was boiling, but not boiling over.

7. 

   Fire is hot.

8. 

   Fire is really hot. Also, not succeeding in the not boiling over

9. The electronic weighing scale in the lab was really really good. 0.01g good. Which of course means it took 10 seconds per reading, which was really not good when you had 28 lumps of wallpaper paste sticking to everything, and you have to adjust their weight by pinching off tiny flakes and waiting 10 seconds per flake. Or, watching as the cooked GRB steams on, completely unaware that it's reducing the accuracy of the reading by losing heat every second. Such joy.
10. Amidst this, few photos were taken, 18 GRB's measurements ruined, 1 after cooking volume not taken, and countless people scared. So, what to do better:

• Perhaps, if you know you're the impatient type and have been doing small scale trials all this while, why for the love of science are you doing 28 sets of finicky steps all at once? Split it up next time.
• Accept that that scale is never going to show you .00g and move on. .5g within the target is perfectly fine for everyone who's not you, .05g is a good compromise if you are you.
• Make sure that people actually know you're going to be elbow deep in flour, or shove that phone under the bed and have plausible deniability. 
• Be James Bond and reccee the lab first. Ask about the apparatus, get comfortable with the set-up, never do the final experiment/set off the big bomb where you have never tried before.
• Plan all of these (including a test batch of four GRB that never got used...) and actually follow them.

Big brother is watching... The dye is yellow, by the way.

LB: Trial 2 Results

LB: Trial 2 Results

Date: 30 June 2012

Time: 3pm-7pm

Room temperature: 27°C

Weather: Sunny

Trial 2 was conducted immediately after Trial 1 to check the repeatability of the results. From figure 3, the volume of the two 40g GRB was greater than their mass, but the opposite is true for the 20g GRB. Out of all the variables I identified initially, mass, volume, surface area or density do not predict the trend in time taken and only surface area to volume ratio is left.

LB: Trial 3 Results

LB: Trial 3 Results

Figure 4:  Photos used to derive values for surface area

Figure 1 uses image-j numbers

You'll notice that of the two methods, I've decided to take only image-j's values for surface area. This is because I think that taking data from different sources and treating it as one set of numbers will increase the difficulty of following these processes, as well as complicate identifying errors. Hence, only one method should be used at this stage, of trials.

As to why image-j was chosen over manual, it is more accurate in measuring areas in the 2D photo . The different radii in figure 2 indicate that the GRB are still not perfectly round, though the difference is smaller than in previous trials and this compromises the accuracy of the manual method. There is no need to find out the radius for calculating areas of spheres and besides I think it is more useful to measure the 2D photo well, since all the GRB are of the same thickness anyway.

Illogical Density 

In figure 1, the uncooked 20g flat is less dense than water, which shouldn't be considering it sank. There are a few other points of contention as well, such as 2/3 of the GRB getting significantly denser (but floating) after cooking. Discussion with my teacher (Ms Tan Beng Chiak) still concluded that this experiment hinged on accurate measurements; if I continue trying to improve experimental method, then ideally at the end I can obtain results that show the GRB getting less dense.

Surface Areas in Figure 2

If density can show how the GRB floats, then surface area is a possible reason as to why. In figure 2, the surface areas before cooking from the two methods are reasonably close, but the areas after cooking differ up to 10 cm². The reasons presented above for using image-j may still stand, but this large difference needs to be addressed in future experiments as well.

Surface Areas in Figure 3

Linked to the above issue, surface area doesn't seem to predict when the GRB will float, but it is possible to get more accurate measurements of surface area.

Director's Cut: Trial 3

Director's Cut: Trial 3

The point of trial 3 was to do a greatly simplified (only 3 GRB, obvious difference in size but same shape, and that shape is easy to make) experiment incorporating the changes in measuring volume. Hopefully it could have revealed that GRB do expand after cooking and previous measurements were just not accurate enough to show that.


In this trial, the density still increased after cooking, but to a maximum of 16+% as compared to trial 2's 30+%. As I was conducting the trials, I've realised that accurate measurements were the most important aspect. 


Most significantly, after looking at my apparatus my teacher said that a spring balance was far too inaccurate for this experiment, so I'm going to have beg, borrow or steal a better one. Honestly, they're much more expensive and the rare people who have them worry about lending them out...

LB: Trial 3 Procedure

LB: Trial 3 Procedure

Research Question: Does the process of gelatinisation cause the GBR to float?
Hypothesis: The higher the surface area to volume ratio, the faster the GBR floats in water.

Steps

1. Measure out 60g each of rice flour and water using a weighing scale, add blue and yellow food colouring and mix until evenly distributed.

 2.  Divide the dough into 3 parts, 60g, 40g and 20g using a spring balance.

3.  Roll all parts into balls and dust with cornflour.

After rolling

l Flatten as illustrated in the other post.

4.  Lay all GRB on black paper covered with plastic, with a ruler in sight, and then take a photo from directly above.

This photo will be used for measuring surface area

5. Wrap the 20g flat in cling wrap, gather the corners of the cling wrap and twist shut.

With as little air space as possible

6. Fill a displacement can with water, and slowly submerge the wrapped GRB while using the 100ml measuring cylinder to catch the displaced water. Record the volume and repeat steps 5-6 for the other two GRB.
7. Using a 250ml cylinder, pour 750ml of water  into a pot. Put the pot on a hotplate set to 120°C and start the stopwatch. When the water has begun to boil, slowly drop all GRB into the water by hand.
 8. Stir continuously with the strainer and record the time it took for each GRB to float. Turn off the hotplate when all GRBs are floating. 

9. Using the strainer, transfer all GRB into a plate while making sure they are not sticking and leave them to cool for 30 minutes.

10. Repeat step 4.

GRB after cooking

11. Repeat steps 5-6, but directly slipping the GRBs into the displacement can without wrapping them.

12. Weigh each GRB with the spring balance again.

LB: How the measurements were derived

LB: How the measurements were derived

This is an explanation (using trial 1, before cooking as an example) of various techniques used to get the results. Some are self explanatory/simple enough to cover in the list of steps, and these are the rest, updated as experiments progress. Note: even though the example is trial 1, image-j was actually used until after trial 3.

1. Surface area- manual and image-j
2. Making of flats from trial 3 onwards
3. Weighing with spring balance
4. Correlation formula/Graphs

1. Surface area

I have used two ways, manually and with image-j software, to find the surface area of each GRB, though how successful each is has yet to be evaluated. In the list of steps, such a photograph was to be taken:

fom trial 1, before cooking, taken with camera held parallel from ground

Manual

Using powerpoint, a ruler and colour-coded squares encircling each GRB was superimposed onto the photograph. 

After the photo has been marked

The ruler from the original photo was to indicate the scale of the photo. The lines of the square extended until the ruler, where the diameter of each GRB is read off two times, length and width wise. Taking the average, surface area is calculated with the formulas πr² (circle) for the flats, and 4πr² (sphere) for the balls. 
Figure 1: Manual calculations for surface area before cooking, trial 1

	Radius before cooking/cm (rounded to 1 dp)
Type of GRB	Derived from length	Derived from width	Average	Surface area before cooking/ cm2 (rounded to 1 dp)
Green 40g flat	3	3.1	3.1	120.8
White 40g flat	2.7	2.9	2.8	98.5
Green 40g ball	2.4	2.5	2.5	78.5
White 40g ball	2	2.2	2.1	55.4
Green 20g ball	1.8	2.1	2	50.3
White 20g ball	1.6	1.6	1.6	32.2

Image-J

Image-J is a free, downloadable software capable of analysing images. This is the developer's website. After the photograph was opened in image-J, I used the set-scale function to declare the number of pixels in 1 cm by drawing to scale a 1 cm line on the ruler. Then, I used the free-hand drawing tool to trace the shape of each GRB and the measure function to analyse and convert into cm² how many pixels the GRB was.

Figure 2: Image-J calculations for surface area before cooking, trial 1

	Surface Area/ cm2 calculated by image-j
Type of GRB	Before cooking
Green 40g flat	32.205
White 40g flat	25.496
Green 40g ball	18.948
White 40g ball	13.867
Green 20g ball	12.027
White 20g ball	9.579

Conclusion

• Because it calculates 2D area, image-J is not applicable for the spherical GRB and there is a great difference between image-J values and manual values. So, I've decided to forgo image-j for future trials and only use the manual method.
• The "spheres" were not perfect spheres. Because of the pliability of the douch, they had no structural integrity and easily lost their shape. Hence, no more tests using round GRB after trial 1.  

2. Making of flats

After trial 1 and 2 measurements were analysed, I realised that using hands to shape the flats led to inconsistency in the shape. After talking with a friend (Zhi Rui), we came up with a way to improve that.

Diagram of the process

Before placing the spherical GRB in, the set-up is covered in cling wrap to prevent sticking.

The blocks are anything (e.g. bowls, cups, pieces of wood), but each set is identical in height and the plate has a flat bottom. This method will make the force applied more even.

3. Weighing with spring balance

Photo from real life

The GRB is placed in a plastic “pouch”, then the hook of the spring balance is forced through the top, leaving the pouch hanging. The measurement is then read off the spring balance and the mass of the plastic is assumed to be negligible.


4. Correlation formula/Graphs

Correlation was calculated with the =CORREL(array1,array2) function in excel, which uses  (pearson product-moment correlation coefficient) as the formula. This has been chosen because the data to be analysed mostly fits Pearson's assumptions that it has interval/ratio measurements, a linear relationship, minimal outliers and homoscedasticity (consistent variance along the trend line). 

example

The graphs for the final experiment are created using Apache OpenOffice instead of the previous Excel.

Director's Cut: Trial 2

Director's Cut: Trial 2

The first two trials were done on the same day (last Wednesday in fact), before analysing the data collected, so the changes dealt with physical problems. After analysing, other flaws were revealed in some of the methodology as well.

• Even with an attempt at squeezing out air, placing uncooked GRB inside waterproof bags to keep them from dissolving in the displacement can still allowed for too much air. The plastic bag was too stiff to be compressed by the water. In retrospect, using a large enough sheet of cling wrap such that the opening could be kept above water would be more accurate.
• A preliminary look at the data indicates that the surface area calculations are going to be problematic. There's no way to make (and preserve) perfectly round spheres or circles (which have an added complication of depth) with according to exact measurements. Have thought of something to try for the flat GRB, but have no idea what to do for the round ones.

Edit: Will not make any more round GRB, instead focusing on investigating surface area:volume with less-curved shapes whose surface areas are easier to measure

I'll post this data after I've polished them 

• I overlooked procuring an apron, or at least a portable dry cloth to wipe off residues of dough. Now my tables are very clean, but my pants look like this:

Water and flour.

In other news, I've (finally) had to learn excel. Yay.

Questions after the two trials:

1. Does the temperature of the water affect its density, and therefore whether the GRBs will float in it?
2. Does the ratio of flour:water affect how the GRBs float? (e.g. density)
3. Since GRBs are water soluble, what does this mean for their cooking in water?
4. Does the amount of water in the pot affect how GRBs float?
5. Prelim points at GRBs shrinking, not expanding. How?

Edit: 1: Yes it does. 
Temp (°C)     Density (kg/m3)
+100    958.4
+80     971.8
+60     983.2
+40     992.2
+30     995.6502
+25     997.0479
+22     997.7735
+20     998.2071
+15     999.1026
+10     999.7026
+4     999.9720
0       999.8395
−10     998.117
−20    993.547
−30     983.85