Question

Water is in streamline flows along a horizontal pipe with non-uniform 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 $2000Pa$. The pressure at another point where the cross-section is $5{cm}^2$ is:

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

Answer 1

The correct option is D $500Pa$

Continuity epi - $A_1{V}_1=A_2{V}_2$

$V_2=2m/s$

Bernouli's epi -

$P_1+\frac{\rho V_1^2}{2}+Z_1=P_2+\frac{\rho V_2^2}{2}+Z_2$

$Z_1=Z_2$ ( horizontal pipe)

$2000+\frac{1000(1{)}^2}{2}=P_2+\frac{1000(2{)}^3}{2}$

$P_2=500Pa$