What generates the energy that makes plastic supermarket bags so noisy?

Question: What generates the energy that makes plastic supermarket bags so noisy?
- Keywords:
  bag,
  noise,
  plastic
Asked by danrumford to Cat, Daz, Holly, Johnson, Pamela on 22 Jun 2011.
- Cat O'Connor answered on 22 Jun 2011:
  
  Hi Dan,
  
  Well I am by no means an expert on plastic bags or anything to do with energy but let’s have a think about it.
  
  Firstly, I think that we generate the energy that makes a plastic bag noisy because if left alone they really don’t make much noise do they? But it’s not just people or other animals that can make a bag go from noisy to quite, wind energy can also do it!
  
  I think the reason why plastic bags are so much noiser than say sandwich ziplock bags is that they are created using a different process. Shopping bags and all plastic bags really are made from a polyethylene film which, when untreated, is kinda floppy and not very noisy, very like a ziplock bag.
  
  But to make a shopping bag easy to handle and economically produced, they stretch the plastic very thin and then fill it with kinda extra fillers to give it a colour and to also stop it being see-through! This also works to make the bad kinda stiffer and crinklier!!
  
  I’m not sure if this is 100% correct but maybe one of the other scientists may know something more about it!
  
  Cat

Question: What generates the energy that makes plastic supermarket bags so noisy?