This month's Challenge Question: Specs & Techs from GlobalSpec:
Make
a model boat of aluminum foil, and float it in a halffull bathtub. If
you sink the boat (topple it), it will end up at the bottom of the
bathtub. Will the pressure at the bottom of the bathtub decrease,
increase, or remain the same?
And the answer is:
When
the boat is floating it displaces a weight of water equal to its weight  this
is the Archimedes' law. When the boat is at the bottom of the bathtub it
displaces a volume of water equal to its own volume. The density of the metal foil (the material
the boat is made of) is larger than the density of water (1.0), otherwise it
would not sink.
The relationship between
the weight (W) of water displaced when the boat is floating and the volume of
water displaced (V) when the boat is at the bottom of the bathtub is precisely
the density of the boat, or in equation form:
or

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