Fluid Dynamics: Practice Problem & Solution

Short Solution (Best for NEET):

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:

Rate of flow \(Q = \frac{\pi P r^4}{8 \eta l}\). Under new conditions, \(Q' = 2Q\), \(r' = 2r\), and \(l' = 2l\), giving \(Q' = \frac{\pi P' (2r)^4}{8 \eta (2l)} = 8 \left(\frac{\pi P' r^4}{8 \eta l}\). Thus, \(8 P' = 2 P\), yielding \(P' = P/4\).