THE experiment!

Zip lock bag A filled with 1l of water










Skewer pierced through spot A1.










Side view of skewer pierced through spot A1.










2nd skewer pierced through spot A2.














3rd skewer pierced through spot A3.












All 3 skewers in zip lock bag A.













Skewer in spot C1












2nd skewer in spot C2.












3rd skewer in spot C3












All 3 skewers in zip lock bag C.











Skewer in spot D1











2nd skewer in spot D2.










All 3 skewers in zip lock bag D

Designing for the final experiment

I did a template for the type of zip lock bag I am using as it saves more time and is also more accurate.






Close up shot of the quarter section of the zip lock bag which I am working on.










Zip lock bag A















Zip lock bag B














Zip lock bag C















Zip lock bag D

Approaching from a different angle

If I am testing on the durability of the bag, then I should test on how many skewers can be poked through it and the amount of water that spills out.



What I did was that I drew squares measuring 2cm by 2cm on the zip lock bag.










I pierced the first skewer in at the bottom row left most square.













The second skewer went in through the next alternate square













And the 3rd one the next alternate square.







In the end it turned out to be this messy and undesirable zip lock bag.














However, poking at spots gave me another idea. Does the distance between the spot where the skewer is poked and the center of the zip lock bag affect the amount of water that spills out?

Consultation with Ms Tan

Getting nowhere with my experiment. So I booked a session with Ms Tan and together we discussed my experiment. A few of the more important things Ms Tan pointed out:

1. I said 'normal plastic bag' when actually referring to the sandwich plastic bag. Ms Tan corrected me as normal to her was the NTUC shopping bag. Everyone has different interpretation of things, so terms used have to be very specific.

2. There are different plastic grades. Maybe I can expand on this.

3. What am I testing for by poking a pencil through a bag? Is it the durability of the bag?

4. I need to set constant variables for my experiment. E.g., size of plastic bag, amount of water initially, amount of time the pencil is poked into the bag

5. May want to consider using skewers instead of pencils because they are smaller in size

Elevator pitch

We have to make a speech in front of the the whole class to try to sell our experiments to our classmates. So I wrote out a speech that is under the time limit which is 3 minutes.




My project is studying materials/ properties that are present inside different types of bags. Bags, as in grocery bags, not handbags. Ziploc bag, sandwich bag, coffee bag, ntuc bag.

My inspiration came from a Steve Spanglers’ experiment, where he held a ziploc bag filled with water over a volunteer’s head, and poked a pencil straight through the bag. No water spilled out.

I have confirmed that this experiment truly works, but what I did was just sticking a pencil through a bag filled with water, with not quantifiable results. This was just a preliminary experiment. I will need to do it again, this time taking note of the independent variables and such. They include, size of bag, amount of water in bag, and having a way to measure the amount of water that spills out. Also, I need to know the materials of the bags, in order to compare them with their properties, because different brands have different compositions of materials.

Thus, right now I don’t have a new hypothesis since my project has taken on a different angle.

Further research on the material of Ziploc bags show that it is mostly made of a material called polymer. To make complicated things simple, polymer has a continuously-linked backbone that allows the pencil to slip in between the molecules strands without tearing the other parts of the bag.
Furthermore, the long chains of molecules even seal back around the pencil to prevent the water from leaking out. This was evident as when I poked a pencil though a dry piece of plastic bag, the edges of the hole created could be seen following the pencil through, leaving the hole snug and fitted.

Plastic bags are often made from polyethylene, which consists of long chains of ethylene monomers. Ethylene is derived from natural gas and petroleum.

I did the same experiment with a paper bag. Water had started dripping out even before the pencil was poked in. When the pencil was poked in, water just started spilling out. This was because the hole created by the pencil just tore and the hole was bigger than the diameter of the pencil.

Paper is mainly made up of cellulose which has weak hydrogen bonds. This may causes a whole paper bag to tear when a sharp pencil is poked through it. Also, wet paper has weak fibres that will cause it to be torn more easily than dry paper.

paper bag

Following on my research question in appendix D, I tested the same experiment with a paper bag. Yup, its the bag that the canteen stall vendor uses to put paus in.

So, as expected, the paper bag totally gave way to the pencil when it was pierced in. The hole made by the pencil just became bigger.

The start of my experiment

To start off my project, I decided to first test out whether the experiment conducted by Steve Spangler was really plausible or not. And the results were excellent, if I may say so. Below are the pictures I have captured:




Items needed: Ziplock bag, wooden pencil, water

Ziplock filled with water.

Sideview of ziplock bag full with water, without the pencil yet.

Pencil is poked entirely through the ziplock bag. No water is spilling out.

Close-up shot. The plastic is 'snug' around the pencil.

Under view. The pencil is really poked entirely though, with its mid-section in the water.

Water starts spilling out as soon as one end of the pencil is removed from the hole it has poked.

Polymer

macromolecule (large molecule) composed of repeating structural units

• subunits connected by covalent chemical bonds.

extraordinary range of properties of polymeric materials

• essential and ubiquitous role in everyday life
• familiar synthetic plastics and elastomers to natural biopolymers such as nucleic acids and proteins that are essential for life.

continuously linked backbone

• used for the preparation of plastics
• consists mainly of carbon atoms
• example: polyethylene, whose repeating unit is based on ethylene monomer.

A PLASTIC IS A POLYMER. BUT A POLYMER IS NOT A PLASTIC.


Source: wikipedia

Where the inspiration came from

Firstly, I have to thank Zek MIn for giving me this idea, on which I researched and found out interesting stuff!

Finalised project- Appendix D

APPENDIX D

Science Investigative Project

Project Proposal Form

Name:

Shi Yuexin ( 21 )

Sec 2/13

Topic of investigation :

Effect of different types of bags filled with water when a sharp pencil is poked right through it.

A	Observations made
	When a zip-lock bag is filled with water and then a sharp pencil is poked right through it without being removed, water doesn’t leak out of the bag. This is due to a special characteristic of the zip-lock bag (see below). What will happen if the same experiment is conducted on other different types of bags?
B	Research Question
	Does the type of bag affect whether a sharp pencil can be poked through it without water spilling out?
C	Hypothesis statement
	The type of bag does affect whether a sharp pencil can be poked through it without water spilling out.
D	A short summary of research done on the area of investigation
	The zip-lock plastic bag is made up of polymers, which are long chains of molecules that give the bag its ‘stretchy’ properties. When the sharp pencil is poked through a zip-lock bag filled with water, the pencil slips in between the molecules strands without tearing the other parts of the bag. Furthermore, the long chains of molecules even seal back around the pencil to prevent the water from leaking out. On the other hand, paper is mainly made up of cellulose which has weak hydrogen bonds. This may cause a whole paper bag to tear when a sharp pencil is poked through it when it is filled with water. Also, wet paper has weak fibres that will cause it to be torn more easily than dry paper. Thus, water would most likely spill out of a paper bag when it is poked through with a sharp pencil.
E	Bibliography (Please refer to RS Students’ Handbook in RS Folder on Inet regarding APA Style Format)
	-Steve Spangler Science The Leak-Proof Bag Retrieved from http://www.stevespanglerscience.com/ -Yahoo Answers! In terms of molecules, how does water soak a piece of paper? Retrieved May 26, 2011 from http://answers.yahoo.com/ -Yahoo Answers! It is much easier to tear wet paper than dry paper. Why? Retrieved May 26, 2011 from http://answers.yahoo.com/

Yet another idea

Dynamo has too many variables like size of stain, amount of washing load...that are hard to control. Zek Min gave me this idea that might work out. Do white candles burn faster than coloured candles? I think I will change it a bit and go home to test it out.

New Idea

http://static.productreview.com.au/pr.products/t/150x150/111839_dynamo.jpg

Dynamo - Superior Stain Removal

Yep, Dynamo laundry detergent! I was doing the laundry yesterday when this sudden idea just popped into my head. Dynamo claims to be this superior stain removal, but is it really? It has appeared on the tv commercials a couple of times, so I went online to search for these commercials. Surprisingly, it goes as far back to 1983. If you think about it, thats really old. Like 28 years. Twice my age. Hmmm.

If I am not wrong, these videos are in chronological order. From the least recent to the most recent. All these four commercials state to pour out one-third of a cup (in the first 2) or one cap-full (in the last 2) of Dynamo laundry liquid detergent, rub some onto the stain, and pour the rest into the wash.

Some things that I can investigate on:

1. Does the kind of fabric affect the removal of the stain?

2. Does the kind of stain affect its removal?

In the commercials, some of the stains used included ketchup, lipstick, gravy, food, clay.

3. Does the amount of Dynamo used affect the removal of the stain?

The ratio of volume of Dynamo to volume of laundry load.

4. Can the stain be removed with ordinary laundry detergent or washing powder, provided the dependent variables remain unchanged.

Pointe shoes

So, I really like the pointe shoes idea...

Some projects regarding pointe shoes:

1. The amount of weight a ballet dancer places on her toes when she dances en pointe. How it affects her toes and whether it causes other deficiencies in the body like stunted growth.

2. The different types of pointe shoes. How a ballet dancer knows which type is more fitted for her. How wearing different types may affect her dancing.

3. The life span of the pointe shoes. How the lifespan can be prolonged.

4. Center of balance when dancing on pointe shoes (the box). How if a ballet dancer is not on the box or is over the box will affect her dancing and body.

5. Can unexperienced people stand on pointe. People of different BMI. How long they can balance.

6. What dance shoes are made of. Materials.

After asking around, I think none of this will actually work. But I will still post it up.

I need ideas.

List of random things that I may want to work on.

1. water bubbles

2. potato chips

3. pointe shoes

4. fast food

These are actually things that I like and would be more interested in doing my project about them. So, hopefully some inspiration will come?