Question

A quid 1.65 g/cm) flows through a horizontal pipe of varying cross section as in the figure below. In the first section, the cross-sectional area is 10.0 cm. the low speed is ws, and the pressure is 1.20 x 10 Pa In the second section, the cross sectional area is so cm. (a) Calculate the smaller section's flow speed. (Enter your answer to at least two decimal places.) 608 90X Your response is off by a multiple of the mys (b) Calculate the smaller section's pressure. 9.606 13 X Your response differs from the correct answer by more than 100 Pa

Answer 1

Solution) Density, rho = 1.65×10^(3) kg/m^3

A1 = 10 cm^2

V1 = 274 cm/s

P1 = 1.20×10^(3) Pa

A2 = 4.50 cm^2

(a) V2 = ?

From equation of continuity

(A1)(V1) = (A2)(V2)

V2 = ((A1)(V1))/(A2)

V2 = (10×274)/(4.50)

V2 = 608.8 cm/s

V2 = 6.08 m/s

(b) Pressure at section 2 , P2 = ?

From Bernoullis equation

P1 + (1/2)(rho)(V1^2) + (rho)(g)(h1) = P2 + (1/2)(rho)(V2^2) + (rho)(g)(h2)

Here since it is horizontal pipe , h1 = h2

P2 = P1 + (1/2)(rho)(V1^2 - V2^2)

P2 = 1.20×10^(3) + (1/2)(1.65×10^(3))(2.74^2 - 6.08^2)

P2 = - 23.1×10^(3) Pa