[Extremely Extreme Extremist]

Maybe I'm confused or stupid. My knowledge of science and chemistry ends at boiling a pot of water.

How does a bomb explode in a pressure cooker, when it's not plugged in and the ingredients are inert?

Is there a reaction that causes it to explode? And with the lid on tight, wouldn't the lid stay locked on?

[lacrew]

I believe the locked lid allows explosives to build more pressure before the whole thing blows apart. Same reason a pipe with threaded caps is good for a bomb.

[ctdonath2]

The “pressure cooker” part enhances an explosive by containing the pressure of the blast until it reaches a higher-than-normal level, then the increased pressure is released suddenly by the pressure cooker structural integrity failing suddenly. Otherwise the explosive comes apart earlier, reducing the blast’s potential.

Think:
- blow air (from your mouth)
- blow air into a balloon until it pops
Notice the difference.