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balu736
1 month ago
13

A fireboat is to fight fires at coastal areas by drawing seawater with a density of 1030 kg/m through a 20-cm-diameter pipe at a

rate of 0.1 m /s and discharging it through a hose nozzle with an exit diameter of 5 cm. The total irreversible head loss of the system is 3 m, and the position of the nozzle is 3 m above sea level. For a pump efficiency of 70 percent, determine the required shaft power input to the pump and the water discharge velocity.
Engineering
1 answer:
grin007 [219]1 month ago
3 0

Answer:

A. 50.93 m/s

B. 201 kW

Explanation:

The pump moves a volume of 0.1 m³ of water every second. The diameter of the nozzle is 5 cm, which translates to 0.05 m, or a radius of 2.5 cm, equivalent to 0.025 m. Thus, the cross-sectional area of the nozzle is calculated as A = πr²

π×0.025²

= 0.001963 m²

Consequently, for 0.1 m³ to pass through this nozzle in 1 second, the velocity must be

0.1 / 0.001963

= 50.93 m/s

The pump is designed to provide energy to water to lift it 4 m above sea level to the nozzle and to accelerate it from rest to 50.93 m/s through the nozzle. Assuming no energy losses, the dynamic energy of the water equals the potential energy it would possess if it remained stationary at a height h.

P.E = k.E

mgh = 0.5mv²

h = v² / 2g

h = 50.93² / (2 × 9.81)

h = 132.21 m

Thus, to facilitate the acceleration of water, a head of 132.21 m is required. The static head is 4 m since the nozzle is raised 4 m above sea level, with an additional heads loss of 3 m due to friction along the system. Therefore, the total head the pump needs to deliver is

132.21 + 4 + 3

= 139.21 m

Using the relationship density = mass / volume implies that mass = density × volume.

The pump moves water at a rate of 0.1 m³ per second. Therefore, in one second, the mass of the water pumped is

0.1 × 1030 = 103 kg

The overall energy transferred from the pump to the water corresponds to

Potential energy, which is expressed as = mgh

= 103 × 9.81 × 139.21

= 140,662.0 Nm/s

= 140,662.0 Watts

However, since the pump operates at 70% efficiency, we find

140,662 = 0.7P where P is the power rendered to the pump

Thus, P = 140,662 / 0.7

= 200,946 Watts

= 201 kW

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Write multiple if statements. If car_year is 1969 or earlier, print "Few safety features." If 1970 or later, print "Probably has
alex41 [274]

Answer:

The following includes the explanation, code, and resulting outputs.

C++ Code:

#include <iostream>

using namespace std;

int main()

{

int year;

cout<<"Enter the car model year."<<endl;

cin>>year;

if (year<=1969)

{

cout<<"Few safety features."<<endl;

}

else if (year>=1970 && year<1989)

{

cout<<"Probably has seat belts."<<endl;

}

else if (year>=1990 && year<1999)

{

cout<<"Probably has antilock brakes."<<endl;

}

else if (year>=2000)

{

cout<<"Probably has airbags."<<endl;

}

return 0;

}

Explanation:

The challenge involved displaying feature messages for a car based on its model year.

Logical conditions were integrated into the coding. The implementation has been verified with multiple inputs producing the expected results.

Output:

Enter the car model year.

1961

Few safety features.

Enter the car model year.

1975

Probably has seat belts.

Enter the car model year.

1994

Probably has antilock brakes.

Enter the car model year.

2005

Probably has airbags.

5 0
25 days ago
You want to determine whether the race of the defendant has an impact on jury verdicts. You assign participants to watch a trial
grin007 [219]

Response:

The confidence scale is an ordinal measurement scale

Clarification:

An ordinal measurement scale is utilized for assessing attributes that can be ranked or ordered, yet the intervals in between attributes lack quantitative meaning. In this scenario, the scale utilized was from 1 to 7, where "1" signifies that the defendant's race has little impact on jury verdicts, and "7" indicates a strong impact of race on such verdicts. For instance, in a survey measuring customer satisfaction for a product, a "1" indicates great dissatisfaction, while "10 " denotes highest satisfaction. In the first instance, it would be incorrect to assert that the difference between a rating of 1, which implies "not at all," and perhaps a 3, is equivalent to the gap between a 5 and a 7, as these numbers merely serve as labels devoid of quantifiable value.

Other types of measurement levels include:

1. Nominal: This is the most straightforward measurement level, employed primarily for categorizing attributes. An example would be gathering data on gender, with categories such as male, female, and transgender.

2. Interval: An interval scale is used when the distances between two attributes hold meaning, but a true zero point is absent from the scale.

3. Ratio: This level combines all three previously mentioned measurements, serving to categorize, show ranking, maintain meaningful distances between attributes, and possess a true zero point. A typical example is measuring temperature using a Celsius thermometer, which has a true zero at 0°C, and the intervals between 5°C and 10°C are equivalent to those between 10°C and 15°C.

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4 days ago
An air duct heater consists of an aligned array of electrical heating elements in which the longitudinal and transverse pitches
Kisachek [217]

Answer:

a) q = 7671 W

T0 = 47.6°C

b) ΔP = 202.3 N/m²

P = 58.2 W

c) hDarray = 2 times hD of an isolated element.

Explanation:

see the image for the solution.

4 0
15 days ago
A bar of 75 mm diameter is reduced to 73mm by a cutting tool while cutting orthogonally. If the mean length of the cut chip is 7
mote1985 [204]

Answer:

r=0.31

Ф=18.03°

Explanation:

Provided:

Original diameter of bar = 75 mm

Diameter post-cutting = 73 mm

Average diameter of the bar d= (75+73)/2=74 mm

Average length of uncut chip = πd

Average length of uncut chip = π x 74 =232.45 mm

Thus, cutting ratio r

Cutting\ ratio=\dfrac{Mean\ length\ of cut\ chip}{Mean\ length\ of uncut\ chip}

r=\dfrac{73.5}{232.45}   r=0.31

Therefore, the cutting ratio equals 0.31.

Now, the shearing angle is given as

tan\phi =\dfrac{rcos\alpha }{1-rsin\alpha }

Next by substituting the values

tan\phi =\dfrac{rcos\alpha }{1-rsin\alpha }

tan\phi =\dfrac{0.31cos15 }{1-0.31sin15 }\

Ф=18.03°

Concluding, the shearing angle is 18.03°.

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1 month ago
Who want to play "1v1 lol unblocked games 76"
Daniel [215]

Answer:I want to know what game to play?

Explanation:

3 0
1 month ago
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