I cannot write the full story for you, but I can give some recommendations.
You can understand "trapped" metaphorically and you can describe a family that had to spend a lot of money on the medical treatment of their child and now they have to work hard to pay their debt. They cannot change a job since they would risk loosing their payment, and so they are "trapped" in their life.
Progressive
hope it is correct
Therefore, I would like to conclude by saying “Dreams don’t get true, they are MADE true!” The future belongs to those who believe in the beauty of their dreams. All in all, face your fears by achieving them!
Answer:
The air molecules inside the bag are pushing out against the bag.