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Fluid Mechanics Density problems 
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#1
Oct1204, 05:15 PM

P: 1

Is this correct?
A 6kg piece of metal displaces 1 liter of water when submerged. What is its density? Density = mass/volume 1 liter of water = 1000 cm3 = 1 kg Ans: 6 kg / 1000 cm3 = .006 cm3 How would this one work out? When a 2.0kg object is suspended in water, it ‘masses’ 1.5 kg. What is the density of the object? I'm guessing: Density = mass/volume = 2.0 kg/1.5 kg = 1.333 Or 2.0 kg/ 1500 cm3 = .00133 cm3 Now I'm totally lost on what to do: A vacationer floats lazily in the ocean with 90% of his body below the surface. The density of the ocean water is 1.025 kg/m3. What is the vacationer’s average density? 


#2
Oct1304, 12:18 AM

Sci Advisor
HW Helper
P: 3,147

The buoyant force is equal to the weight of the water displaced (Archimedes principle). That allows you to do a force balance from which you can ultimately determine the volume of the swimmer!



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