Sorry about the title, but that's the example I'm going to use in this question.

 

I just have a misunderstanding about something to help clear some things up for myself about a theory of mine I'm working on.

 

Imagine a Ziploc sandwich bag or something similar which can be sealed to be air tight. All of the air is pressed out of it and it's completely flat.

 

Now imagine trying to pull apart the two flat sides of the main plastic body. You won't be able to because no air or anything else is able to seep in to it in order for the bag to expand or blow up. Also, because of the pressure of the earths atmosphere I guess.

 

Here's my question:

If this were attempted in Space or in a Vacuum, would it still be basically impossible to pull the bag apart given that there wouldn't be any atmospheric pressure on the outside of the bag?

 

 

This is the best example I can come up with that will help answer some things going on in my mind about a theory I'm trying to come up with about something. But ya, the plastic bag itself is obsolete and it's just an example of something else.

 

I'll clarify later depending on what the answer is. It's very interesting too!

Without air pressure outside the bag, you should be able to pull the two sides of it apart, although it wouldn't look 'inflated'

If you hold the - open - bag under water and pull the sides apart, you should get a similar effect; as if you were in space.

The thought experiment which is easier to vizualise, is to use a syringe instead of a bag.

If a take a syringe and place my finger over the end, then try to pull the plunger back, the surrounding atmosphere will impede me, where as if I do the same thing in space, with no atmospheric pressure, I should be able to pull the plunger out.

Yes that is a much better example.

 

So in a vacuum, one could pull the plunger all the back in a syringe even if the head and everywhere else were completely air tight/sealed? If i understand that correctly anyways.

These might be of interest

 

http://en.wikipedia.org/wiki/Magdeburg_hemispheres

http://physics.kenyon.edu/EarlyApparatus/Pneumatics/Magdeburg_Hemispheres/Magdeburg_Hemispheres.html

Yes that is a much better example.

 

So in a vacuum, one could pull the plunger all the back in a syringe even if the head and everywhere else were completely air tight/sealed? If i understand that correctly anyways.

 

Yes.