# physics

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The average human has a density of 940 kg/m3 after inhaling and 1028 kg/m3 after exhaling.

(a) Without making any swimming movements, what percentage of the human body would be above the surface in the Dead Sea (a lake with a water density of about 1230 kg/m3) in each of these cases?

(b) Given that bone and muscle are denser than fat, what physical characteristics differentiate "sinkers" (those who tend to sink in water) from "floaters" (those who readily float)?

• physics -

force up = force down

force up = volume in water* density of water * g

force down = weight = m g = total volume * body density * g

so for example after inhaling

force up = volume in water * 1230 * g
force down = total volume * 940* g
so
volume in water/total volume = 940/1230
multiply by 100 to get percent

Of course the less dense material floats higher, the fat person.
force down =

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