Garbage Bag Experiment

When we first started this project, it was in the beginning of the week and we were just learning about air pressure. Our main objective was to blow up a garbage bag using straws with someone actually sitting on top then we were supposed to explain how the bag expanded. We concluded that it was because of air pressure. We learned that even though there was little air in the garbage bag to begin with, there was still pressure that forced the bag up in certain places and down in others when the air pressure outside the bag was stronger. It took a bit to fill the garbage bag with air and raise Reilly, I think that was his name, off the floor. We added more air particles into the bag and since they were warmer, they collided with each other more often, creating a greater air pressure. I guess this explains why Reilly felt the garbage bag, well the air pressure inside it, pushing him up off the ground and why the bag was able to expand. I've known that if blow air into something, in most cases balloons, then it will expand, but I guess I learned that there is air pressure that is a key factor, on the outside it presses in and on the inside it presses out, that if the pressure outside is greater it contracts, but if the pressure inside is greater it expands.