Q: A horizontal pipe line carries water in a streamline flow. At a point along the pipe where the cross-sectional area is 10 cm^{2}, the velocity of water is 1 m/s and the pressure is 2000 Pa. What is the pressure at another point where the cross-sectional area is 5 cm^{2}.

**Click to See Answer : **

Sol: According to equation of continuity

A_{1} v_{1} = A_{2} v_{2}

v_{2} = (10/5) × 1 =2m/s

Now, according to Bernoulli’s equation,

$\large P_1 + \frac{1}{2}\rho v_1^2 = P_2 + \frac{1}{2}\rho v_2^2 $ (∵ horizontal pipe)

$\large 2000 + \frac{1}{2}\times 10^3 \times 1^2 = P_2 + \frac{1}{2}\times 10^3 \times 2^2 $

P_{2} = 500 Pa