Question

1. A cylindrical object floats inside water to have 3/4" of its volume inside. Find the density of the object.
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Answer 1

Answer:

Let volume of object be V and density p .

Now mass = volume × density = pv

Now since object is floating in water , buoyancy force must balance it's weight .

$f(buoyancy) = mg = \rho vg$

Now 3/4 V is inside water so buoyancy force will be

$\rho(w) .\frac{3v}{4} .g = \rho \: vg \\ \\ \rho = \frac{3}{4} \times \rho(w)$

Water density is 1 gm/ cm3

So p = 3/4 gm/cm3