Fluid Dynamics: Practice Problem & Solution
A drop of water falls in air with terminal velocity \(v_0\). If 27 such drops combine to form a big drop. Then terminal velocity of this new big drop will be:
Solution Explained:
To solve this problem, we apply the core principles of Fluid Dynamics. Understanding the underlying formula is key to arriving at the correct answer below:
When 27 identical small drops of radius \(r\) coalesce, the radius \(R\) of the single large drop is \(R = 27^{1/3}r = 3r\). Since terminal velocity \(v \propto r^2\), the new terminal velocity is \(v' = 3^2 v_0 = 9v_0\).
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