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A water tower is a familiar sight in many towns. The purpose of such a tower is to provide storage capacity and to provide sufficient pressure in the pipes that deliver the water to customers. The drawing shows a spherical reservoir that contains 5.25  105 kg of water when full. The reservoir is vented to the atmosphere at the top. For a full reservoir, find the gauge pressure that the water has at the faucet in (a) house A and (b) house B. Ignore the diameter of the delivery pipes

Respuesta :

The image of the water tower and the houses is in the attachment.

Answer: (a) P = 245kPa;

(b) P = 173.5 kPa

Explanation: Gauge pressure is the pressure relative to the atmospheric pressure and it is only dependent of the height of the liquid in the container.

The pressure is calculated as: P = hρg

where

ρ is the density of the liquid, in this case, water, which is ρ = 1000kg/m³;

When it is full the reservoir contains 5.25×10⁵ kg. So, knowing the density, you know the volume:

ρ = [tex]\frac{m}{V}[/tex]

V = ρ/m

V = [tex]\frac{5.25.10^{5}}{10^{3}}[/tex]

V = 525 m³

To know the height of the spherical reservoir, its diameter is needed and to determine it, find the radius:

V = [tex]\frac{4}{3}.\pi.r^{3}[/tex]

[tex]r = \sqrt[3]{ \frac{3}{4\pi } .V}[/tex]

r = [tex]\sqrt[3]{\frac{525.3}{4\pi } }[/tex]

r = 5.005 m

diameter = 2*r = 10.01m

(a) Height for House A:

h = 15 + 10.01

h = 25.01

P = hρg

P = 25.01.10³.9.8

P = 245.10³ Pa or 245kPa

(b) h = 25 - 7.3

h = 17.71

P = hρg

P = 17.71.1000.9.8

P = 173.5.10³ Pa or 173.5 kPa

Ver imagen cristoshiwa

The gauge pressure at house A, and B, is the measurement of pressure

relative to the pressure of the atmosphere.

  • The gauge pressure at house A is approximately 244.5 kPa.
  • The gauge pressure at house B is approximately 173.116 kPa.

Reasons:

Question parameters;

Mass of water in the tower, m = 5.25 × 10⁵ kg

Shape of the reservoir = Spherical

Height of the bottom of the reservoir above the main ground level = 15.0 m

Height of the house A above the ground = 0

Height of the house B above the ground = 7.30 m

(a) Required:

The gauge pressure at house A

Solution:

The density of the water, ρ ≈ 997 kg/m³

[tex]\mathrm{Volume \ of \ water \ in \ the \ tank,} \ V = \dfrac{5.2 \times 10^5 \, kg}{997 \, kg/m^3} \approx 526.58 \, m^3[/tex]

Volume of water in the filled tank = Volume of the tank ≈ 526.28 m³

[tex]\mathrm{Volume \ or \ a \ sphere, } V = \dfrac{4}{3} \cdot \pi \cdot r^3[/tex]

Therefore;

[tex]\mathrm{Volume \ or \ the \ spherical \ tank} = \dfrac{4}{3} \cdot \pi \cdot r^3 \approx 526.28[/tex]

Which gives;

[tex]r = \sqrt[3]{\dfrac{526.58}{\pi} \times \dfrac{3}{4} } \approx 5[/tex]

The diameter of the tank = The height of the tank, h = 2 × r

∴ h = 2 × 5 m = 10 m

The gauge pressure is the pressure above the prevailing atmospheric

pressure;

  • For the system vented to the atmosphere, [tex]P_{gauge}[/tex] = ρ·g·h

Therefore;

The gauge pressure at house A, [tex]P_{gA}[/tex] = 997 × 9.81 × (10 + 15) = 244514.25

The gauge pressure at house A, [tex]P_{gA}[/tex] = 244514.25 N/m² ≈ 244.5 kPa

(b) Required:

Gauge pressure at house B

At house B, we have;

Gauge pressure at house B, [tex]P_{gB}[/tex] = 997 × 9.81 × (10 + 15 - 7.3) = 173116.089

The gauge pressure at house B = 173116.089 N/m² ≈ 173.116 kPa

Learn more here:

https://brainly.com/question/20709159

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