Same mass, different displaced volume

A 0.60 kg solid of density 3000 kg/m³ is carried on a floating platform in water of density 1000 kg/m³. It is lowered into the water and sinks. The platform remains afloat in a vertical-sided tank of horizontal area 0.20 m². Nothing spills or dissolves and no air is trapped.

What is the settled water-level change, positive upward?

Organize the givens & assumptions

m = 0.60 kg
ρsolid = 3000 kg/m³
ρwater = 1000 kg/m³
Tank area = 0.20 m²

Settled hydrostatic equilibrium in uniform gravity; stable stated orientation, no contact forces unless stated, negligible air buoyancy and surface tension, no absorption, trapped gas or spilling.

A $-2.0\ \mathrm{mm}$
B $+2.0\ \mathrm{mm}$
C $0\ \mathrm{mm}$
D $-3.0\ \mathrm{mm}$

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