Question

Water flows through a horizontal tube as shown in the figure. If the difference of heights of water column in the vertical tubes is $h=0.02m$, and the areas of cross section at A and B are $4\times {10}^{-4}{m}^2$ and $2\times {10}^{-4}{m}^2$, respectively, then the rate of flow of water across any section is

• A. $130\times {10}^{-6}{m}^3/s$
• B. $146\times {10}^{-6}{m}^3/s$
• C. $160\times {10}^{-6}{m}^3/s$
• D. $170\times {10}^{-6}{m}^3/s$

Answer 1

Answer: (B)

Using the continuity equation we have $v_A{a}_A=v_B{a}_B$ or
$v_A\times 4=v_B\times 2$
or
$v_B=2v_A$