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Phantasy [73]
3 years ago
10

In very early human history, complex sanitation systems were not needed because settlements were usually very small, like the vi

llage shown below.
However, as cities became larger and population densities increased, one major advancement was the development of _______, which helped to channel wastewaters away from human populations more effectively than in the past.
A.
fountains
B.
water towers
C.
sewer systems
D.
dams

Engineering
2 answers:
victus00 [196]3 years ago
8 0

Answer: sewer systems

Explanation:

faltersainse [42]3 years ago
4 0
Answer:
C. Sewer Systems
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Calculate total hole mobility if the hole mobility due to lattice scattering is 50 cm2 /Vsec and the hole mobility due to ionize
Ad libitum [116K]

Answer:

The total hole mobility is 41.67 cm²/V s

Explanation:

Data given by the exercise:

hole mobility due to lattice scattering = ul = 50 cm²/V s

hole mobility due to ionized impurity = ui = 250 cm²/V s

The total mobility is equal:

\frac{1}{u} =\frac{1}{ul} +\frac{1}{ui} \\\frac{1}{u}=\frac{1}{50} +\frac{1}{250} \\u=41.67cm^{2} /Vs

5 0
3 years ago
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A driver complains that his front tires are wearing
Margarita [4]

Answer:

The correct option is;

Neither A nor B

Explanation:

The location of the where the thread wears in tire that has too high inflation is at the thread pattern center due to the reduced size of the contact patch with the load of the car resting on the central portion of the tire's contact surface

When the wear occurs at the outer edges of the tire, the load of the car rests on the outer edges as the contact patch increases due to the tire being under-inflated

Camber is the slope provided in road pavement to drain off water from the road

Roads with camber has a raised middle portion and wear due to camber includes outer-edge tread wear, inner-edge tread wear and tire feathering

8 0
3 years ago
What does it mean when it says technology is A dynamic process
Degger [83]

Answer:

It studies the process of technological change. Under the field of Technology Dynamics the process of technological change is explained by taking into account influences from "internal factors" as well as from "external factors

Explanation:

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3 years ago
Water vapor at 6 MPa, 600 degrees C enters a turbine operating at steady state and expands to 10kPa. The mass flow rate is 2 kg/
kirill115 [55]

Answer:

Explanation:

Obtain the following properties at 6MPa and 600°C from the table "Superheated water".

h_1=3658.8KL/Kg\\s_1=7.1693kJ/kg.k

Obtain the following properties at 10kPa from the table "saturated water"

h_{f2}=191.81KJ/Kg.K\\h_{fg2}=2392.1KJ/Kg\\s_{f2}=0.6492KJ/Kg.K\\s_{fg2}=7.4996KJ/Kg.K

Calculate the enthalpy at exit of the turbine using the energy balance equation.

\frac{dE}{dt}=Q-W+m(h_1-h_2)

Since, the process is isentropic process Q=0

0=0-W+m(h_1-h_2)\\h_2=h_1-\frac{W}{m}\\\\h_2=3658.8-\frac{2626}{2}\\\\=2345.8kJ/kg

Use the isentropic relations:

s_1=s_{2s}\\s_1=s_{f2}+x_{2s}s_{fg2}\\7.1693=6492+x_{2s}(7.4996)\\x_{2s}=87

Calculate the enthalpy at isentropic state 2s.

h_{2s}=h_{f2}+x_{2s}.h_{fg2}\\=191.81+0.87(2392.1)\\=2272.937kJ/kg

a.)

Calculate the isentropic turbine efficiency.

\eta_{turbine}=\frac{h_1-h_2}{h_1-h_{2s}}\\\\=\frac{3658.8-2345.8}{3658.8-2272.937}=0.947=94.7%

b.)

Find the quality of the water at state 2

since h_f at 10KPa <h_2<h_g at 10KPa

Therefore, state 2 is in two-phase region.

h_2=h_{f2}+x_2(h_{fg2})\\2345.8=191.81+x_2(2392.1)\\x_2=0.9

Calculate the entropy at state 2.

s_2=s_{f2}+x_2.s_{fg2}\\=0.6492+0.9(7.4996)\\=7.398kJ/Kg.K

Calculate the rate of entropy production.

S=\frac{Q}{T}+m(s_2-s_1)

since, Q = 0

S=m(s_2-s_1)\\=2\frac{kg}{s}(7.398-7.1693)kJ/kg\\=0.4574kW/k

6 0
3 years ago
List the main activities of exploration??
Trava [24]

Answer:  Exploration includes plethora of activities and depend upon the kind  of exploration a person is doing. But most include some of the basic activities like research , investigation, planning and execution.

Suppose we want to explore new petroleum sites then we would have to start with studying the geography of that area, then according to our research we will analyse the hot spots or the sector where probability of finding of oil field is highest, post that appropriate man power is skilled professionals, tools and machinery will be brought at the site so that execution can take place.

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3 years ago
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