Water Flowing from a Tank?

[匿名]

2015-12-10 5:26 pm

Water flows steadily from an open tank as shown in the figure. (Figure 1) The elevation of point 1 is 10.0 meters, and the elevation of points 2 and 3 is 2.00 meters. The cross-sectional area at point 2 is 0.0480 square meters; at point 3, where the water is discharged, it is 0.0160 square meters. The cross-sectional area of the tank is very large compared with the cross-sectional area of the pipe.

Part A : Assuming that Bernoulli's equation applies, compute the discharge rate dVdt.
Express your answer in cubic meters per second.

Part B: What is the gauge pressure at point 2?
Express your answer in pascals.

I got Part A but cannot figure out part B .

回答 (1)

麻辣

2015-12-14 11:38 pm

Water Flowing from a Tank?

Water flows steadily from an open tank

The elevation of point 1 H1 = 10.0 m,

points 2 and 3 is H2 = H3 = 2.00 m.

The cross-sectional area at point 2 A2 = 0.0480 m^2

A3 = 0.0160 m^2, where the water is discharge

The cross-sectional area of the tank is very large compared with the

cross-sectional area of the pipe.

(A) Bernoulli's equation computes discharge rate = ? m^3/s

H1 = H2 + V3^2/2g

V3 = √[2g(H1 - H2)]

= √[2*9.8*(10 - 2)]

= √(19.6*8)

= 12.52198 m/s

Q = A3*V3

= 0.0160 * 12.52198

= 0.20 m^3/s

(B) P2 = ? Pascal

V2 = V3

H1 = H2 + P2 + V2^2/2g

P2 = H1 - H2 - V2^2/2g

= 8 - 12.52^2/2*9.8

= 0.00253 m

= 0.00253 m * (1000 kg/m^3 * 9.8 N/kg)

= 24.8 N/m^2

= 24.8 Pascals

👍 2 👎 1