Question

A horizontal pipe of non-uniform cross-section allows water to flow through it with a velocity $1m{s}^{-1}$ when pressure is $50kPa$ at a point. If the velocity of flow has to be $2m{s}^{-1}$ at some other point, the pressure at that point should be

• A. 50 kPa
• B. 100 kPa
• C. 48.5 kPa
• D. 24.25 kPa

Answer 1

Answer: (C)

According to Bernoulli’s equation for horizontal pipe,


$P_1+\frac{1}{2}\rho v_1^2=P_2+\frac{1}{2}\rho v_2^2$
$\Rightarrow P_1+\frac{1}{2}\rho \left(v_1^2-v_2^2\right)=P_2$
$\Rightarrow P_2=50\times 10^3+\frac{1}{2}\times 10^3\times \left(1^2-2^2\right)$
$\Rightarrow P_2=50\times 10^3-1.5\times 10^3$
$=48.5kPa$