Question

Water is in streamline flow along a horizontal pipe with nonuniform cross-section. At a point in the pipe where the area of cross-section is $10 \, cm^2$, the velocity of water is 1 $ms^{-1}$ and the pressure is $2000\, Pa$. The pressure at another point where the cross sectional area is $5 \, cm^2$ is...........

• A. 1000 Pa
• B. 500 Pa
• C. 4000 Pa
• D. 2000 Pa

Answer 1

Answer: (B)

According to equation of continuity
$A_{1} v_{1} =A_{2} v_{2}$
$10 \times 1 =5 \times v_{2}$
$v_{2} =2 m / s$
$\frac{p_{1}}{\rho}+\frac{v_{1}^{2}}{2} =\frac{p_{2}}{\rho}+\frac{v_{2}^{2}}{2}$
$\frac{2000}{1000}+\frac{1^{2}}{2} =\frac{p_{2}}{1000}+\frac{2^{2}}{2}$
$p_{2} =500\, Pa$