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Old 08-29-2016, 05:44 PM
Mangetout Mangetout is offline
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Join Date: May 2001
Location: England
Posts: 57,106
Originally Posted by SigMan View Post
The staves are made like a wedge so when they are put together and the iron rings hammered in place they form a seal.
This is the correct answer. Wooden barrels and buckets are created by straining the staves against metal rings - if the rings were square, rather than circular, the forces acting on them would be trying to bend them toward a more circular shape.

Buckets are actually round for similar reasons that soap bubbles are round - it's all about forces pushing outwards against a constraining boundary.