Fluid Mechanics Viscosity Question 119
A streamlined body falls through air from a height on the surface of a liquid. If d and D(D > d) represents the densities of the material of the body and liquid respectively, then the time after which the body will be instantaneously at rest, is
Options:
A) 9 minutes
B) 7 minutes
C) 5 minutes
D)3 minutes
Show Answer
Answer:
Correct Answer: B
Solution:
Time taken to be emptied for h height, $ t=\sqrt{\frac{2h}{g}} $ and for $ \frac{h}{2} $ height, $ t’=\sqrt{\frac{2(h/2)}{g}}=\sqrt{\frac{h}{g}} $ \ $ \frac{t’}{t}=\frac{1}{\sqrt{2}}\Rightarrow t’=\frac{t}{\sqrt{2}}=\frac{10}{\sqrt{2}}=7\ \text{seconds} $
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