Materials Required:
l Small paper bag (lunch bag)
l Pail
l Water
l String
Procedure:
- Set the bag into a pail filled with water.
- Allow the bag to fill with water, then tie it closed with a piece of string. The bag will drift in the water without any harm.
- Now raise the bag from the water by pulling on the string. The paper will burst open immediately. Can you explain why?
This Is What Happens:
While in the pail, the paper is surrounded on all sides by a uniform medium. That is, all forces are balanced and there is no strain in any particular spot. However, as the bag is raised, the air is less dense than the water inside the bag. Gravity pulls downward on the water, and the bag is not able to withstand this force.
