Chief Scientist Carl Nelson demonstrates how a slight imbalance in air pressure can have dramatic consequences.
A 55 gallon steel drum is filled with a little water and then heated with a rosebud torch. Once the water has turned to steam the drum is quickly sealed and cooled on a tray of ice.
As the vapor inside the drum cools, it condenses into liquid water and reduces the air pressure inside the drum. This imbalance in air pressure between the inside and outside causes the drum to collapse.
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