Strength of a Bag

If you take a plastic bag and fill it with items until It breaks, will another layer of plastic bag make the first plastic bag stronger? Is it safe to say that if a plastic bag is made thicker by layering more plastic nags in it, they could contain more items?
This project tests the linear relationship between the number of bags layered up and the weight they can support. There could be a change or none at all.
What you need:
• Several plastic bags
• A weighing scale
• Uniform weights

Use plastic bags because they are easy to acquire in bulk. The weights will simulate the items that you place in the plastic bags when you shop around or transport things. A place to hang the plastic bag is helpful. An existing iron nail on a wall or a metal hook on your gate will do fine.

How to do it:
1. Take one of the bags and find its breaking point. Hang it somewhere and fill it with sandbags or Ziploc bags filled with sand. Be sure to place a weighing scale under the plastic bag. Keep filling the bag until it breaks. Note what part of the bag starts to tear. As the bag breaks, the weights will fall on the weighing scale. When this happens, the exact weight limit of the single plastic bag should show.
2. Insert one intact plastic bag into another. One plastic bag lines the other, making an extra thick plastic bag. Hang it over the weighing scale again and fill it with sandbags. Record the weight at which it breaks. Repeat the process using more plastic bags, at least three times.
3. The more repetitions you perform, the more data you collect.
Analysis of Data:
With the data, you gather, create a graph. Use the variables “Weight Held” and “Number of Plastic Bags”. What is your conclusion? What is the overall behavior of the bag strength as you added more plastic bags?
Also, try this experiment with paper towels or paper bags and see which brand is the toughest.

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