Find tracks hydrostatic
An object 100 g is immersed in a fluid of density 800 g/L, so that floats with half its volume below. Then, the object is immersed in another fluid of unknown density, so it floats at the third of its volume below.
Based on these data, find:
a)If a new body is placed over the object so that the object is completely submerged in water (the upper surface of the submerged object coincides with the surface of the water), find the new body mass in grams.
The answer is 150.
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1 solution
We know that, VIN/VTOTAL= DOBJECT/DLIQUID Therefore, ½= DOBJECT/800g/L, i.e. DOBJECT= 400g/L
When the object is immersed in water, it experiences an upward force (i.e. buoyant force or FB) which is equal to VOBJECT.DWATER.g
Therefore, FNET= FB - M.g
When another object of mass ‘m’ is placed on the first, the system rests in equilibrium. Hence, FNET= m.g= FB - M.g => m.g= V.D.g - M.g
=> m= (100g/400g/L* 1000g/L) – (100g) [V= M/DOBJECT; DWATER= 1000g/L] Therefore, m= 150g