# Why are man hole covers round?

**URL:** <https://forums.speedlife.net/t/why-are-man-hole-covers-round/41996>\
**Category:** NYSpeed Off Topic\
**Created:** [January 17, 2008, 11:49am UTC](https://forums.speedlife.net/t/why-are-man-hole-covers-round/41996 "2008-01-17T11:49:51Z")\
**Posts on this page:** 1\
**Showing post:** 22

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**Author:** ![rdandy5875](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/rdandy5875/32/7511_2.png) [@rdandy5875](https://forums.speedlife.net/u/rdandy5875)\
**Post date:** [January 17, 2008, 12:11pm UTC](https://forums.speedlife.net/t/why-are-man-hole-covers-round/41996/22 "2008-01-17T12:11:27Z")

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> [@Fry](#):
>
> The water level goes down. A buoyant object (like a boat/rock/person system) will displace an amount of water equal to its weight. A non-bouyant object like a rock will displace an amount of water equal to its volume. Since the rock is denser than water, an equal weight of water is more volume than the rock.

+1, read the reply before I though about it myself though.

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