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blazin247nc

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**Fluid Mechanics -- Floating Bodies**

## Homework Statement

A solid block with specific gravity 0.9 floats so that 75% of the body is submerged in water and the other 25% sits in an unknown fluid layered above the water. Find the specific gravity of the unknown fluid.

density of water = 1000 kg/m^3

density of the block = 900 kg/m^3 (from SG)

## Homework Equations

For floating bodies W = Fb

W = d*g*V

Fb = d*g*Vdisplaced

## The Attempt at a Solution

W = Wblock + Wfluid

Wblock = 900*9.8*(a+b) ----->length and width cancel when equations are set equal

Fb = 1000*9.8*b -------->a = height of block above water (.25) b= below water (.75)

This is where I get lost. I know I need to incorporate the weight of the unknown fluid pushing down on the block, but does the weight of the fluid only include the displaced weight?

where:

W = 900*9.8*(a+b) + d-fluid*9.8*a ? But when I do this I get a negative density :(