Mystery #2Tier 2water / pressure / forces
Why is a giant dam wall built far thicker at the bottom than the top?
A great dam holds back a whole lake, and its wall is a peculiar shape: slim along the top but enormously thick and heavy at the base, like a wedge. If it is the same lake leaning on all of it, why not build the wall one even thickness top to bottom? Why pile all that extra concrete at the very foot?
Your guess
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