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faust18 [17]
2 years ago
13

Steam at 1 MPa, 300 C flows through a 30 cm diameter pipe with an average velocity of 10 m/s. The mass flow rate of this steam i

s: (d) 3.78 kg/s (a) 0.731 kg/s(b) 2.74 kg/s (c) 3.18 kg/s
Engineering
1 answer:
stealth61 [152]2 years ago
7 0

Answer:

\dot m = 2.74 kg/s

Explanation:

given data:

pressure 1 MPa

diameter of pipe  =  30 cm

average velocity = 10 m/s

area of pipe= \frac[\pi}{4}d^2

                 = \frac{\pi}{4} 0.3^2

A = 0.070 m2

WE KNOW THAT mass flow rate is given as

\dot m = \rho A v

for pressure 1 MPa, the density of steam is = 4.068 kg/m3

therefore we have

\dot m = 4.068 * 0.070* 10

\dot m = 2.74 kg/s

You might be interested in
Python Homework
DerKrebs [107]

Answer:

  1. TAX_RATE = 0.20
  2. STANDARD_DEDUCTION = 10000.0
  3. DEPENDENT_DEDUCTION = 3000.0
  4. # Request the inputs
  5. grossIncome = float(input("Enter the gross income: "))
  6. numDependents = int(input("Enter the number of dependents: "))
  7. # Compute the income tax
  8. taxableIncome = grossIncome - STANDARD_DEDUCTION - \
  9. DEPENDENT_DEDUCTION * numDependents
  10. incomeTax = taxableIncome * TAX_RATE
  11. # Display the income tax
  12. print("The income tax is $" + str(round(incomeTax,2)))

Explanation:

We can use round function to enable the program to output number with two digits of precision.

The round function will take two inputs, which is the value intended to be rounded and the number of digits of precision. If we set 2 as second input, the round function will round the incomeTax to two decimal places. The round function has to be enclosed within the str function so that the rounded value will be converted to a string and joined with the another string to display the complete a sentence of income tax info.

5 0
2 years ago
A system consisting of 3 lb of water vapor in a piston–cylinder assembly, initially at 350°F and a volume of 71.7 ft3, is expand
Alla [95]

Answer:

isobaric expansion = 281.09 Btu

isothermal compression= 72 Btu

Explanation:

The first law of thermodynamics is:

Q_{AB}=W_{AB}+deltaU_{AB}

where:

Q=heat transferred

W= work

U=internal energy  

W_{AB}=P*(V_{B}-V_{A})

U_{AB}=n*C_{v}(T_{2}-T_{1})

P=pressure, V= volume, T= temperature, n =  moles, Cv= specific heat at constant volume.

In a isobaric process heat transferred is:

Q=P*(V_{B}-V_{A})+n*C_{v}(T_{2}-T_{1})

For an isothermal process (T2-T1 = 0) so

Q=P*(V_{B}-V_{A})= W_{AB}

From the data we know that the energy transferred to the system in the isothermal compression by work was 72 Btu that is the heat transferred to the system.

For the first process

Q=P*(V_{B}-V_{A})+n*C_{v}(T_{2}-T_{1})

we have to properties at the beginning of the process : temperature (350°F) and specific volume (V/mass)

specific-volume=\frac{71.7 ft^{3}}{3Lb}=23.9\frac{ft^{3}}{Lb}

we use this information in the appropriate unit to find the pressure in thermodynamic tables.

T1= 176°C

v1= 1.49 m^3/kg

P=1.37 bar

in the second state we have

P=1.37 bar =137000Pa

v_{2}=\frac{85.38ft^{3}}{3Lb}= 28.46\frac{ft^{3}}{Lb}

with thee properties we check in the thermodynamic tables

T2= 255°C

n=mass/Mw = 3Lb*\frac {1kg}{2.2Lb}*\frac{1000gr}{1kg}*\frac{1mol}{18gr}=75.75 mol

we usually find Cp on tables for water but from the Mayer relation we have:

C_{v}=C_{p}+R

Cp for water vapor is: 33.12 J/mol*K

R=8.314 J/mol*K

Cv= 41.434 J/mol*K

replacing in the equation for Q

Q=137000 Pa*(2.41m^{3}-2.030m^{3})+75.75mol*41.434\frac{ J}{mol*K}*(528.15-449.81 K)=296569J

296569J =281.09 Btu

5 0
2 years ago
A person puts a few apples into the freezer at -15oC to cool them quickly for guests who are about to arrive. Initially, the app
frosja888 [35]

Answer:

Temperature at center of apples = 11.2⁰C

Temperature at surface of apples = 2.7⁰C

Amount of Heat transferred = 17.2kJ

Explanation:

The properties of apple are given as:

k = 0.418 W/m.°C

ρ = 840 kg/m³

Cр = 3.81 kJ/kg.°C

α = 1.3*10 ⁻⁷ m²/s

h = 8 W/m².°C

d = 0.09m

r = 0.045m

t = 1 hour = 3600s

<h2>Solution</h2>

Biot number is given as:

Bi = \frac{hr}{k}= \frac{8\cdot0.045}{0.418}=0.861

The constants λ₁ and A₁ corresponding to Biot number (from the table) are:

λ₁ = 1.476

A₁ = 1.239

Fourier Number is:

T = \frac{a\cdot{t}}{r^2} = \frac{(1.3\cdot10^{-7})(3600)}{0.045^2}= 0.231> 0.2

As Fourier Number > 0.2 , one term approximates solutions are applicable

The temperature at the center of apples, The temperature at surface of apples and Amount of heat transfer is found in the ATTACHMENT.

8 0
2 years ago
What properties should the head of a carpenter’s hammer possess? How would you manufacture a hammer head?
BabaBlast [244]

Properties of Carpenter's hammer possess

Explanation:

1.The head of a carpenter's hammer should possess the impact resistance, so that the chips do not peel off the striking face while working.

2.The hammer head should also be very hard, so that it does not deform while driving or eradicate any nails in wood.

3.Carpenter's hammer is used to impact smaller areas of an object.It can drive nails in the wood,can crush  the rock and shape the metal.It is not suitable for heavy work.

How hammer head is manufactured :

1.Hammer head is produced by metal forging process.

2.In this process metal is heated and this molten metal is placed in the cavities said to be dies.

3.One die is fixed and another die is movable.Ram forces the two dies under the forces which gives the metal desired shape.

4.The third process is repeated for several times.

5 0
2 years ago
Identify an object in your house that contains a physical system and list three questions you could use to define the system
jonny [76]

Answer:

ALL CAREFULLY ANSWERED CORRECTLY

Explanation:

1) A loaf of Bread PHYSICAL SYSTEM

✓ How can the environment affect the edibility of the bread

✓ What are the constituents that makes up the bread

✓ What process is involved in these constituents mixing to form the loaf.

2) The law of thermodynamics makes us to understand that when heat/energy passes through a system, the systems internal energy changes with respect to the conservation of energy law. That is energy lost = energy gained. Typically, ice would melt in a cup of hot tea because of the thermal energy in the molecules of the hot tea. When you heat a material, you are adding thermal kinetic energy to its molecules and usually raising its temperature. The temperature of the ice raises due to the kinetic energy added to it and it melts to water.

3) The theory of systems view the world as a complex system of interconnected parts. If we consider the society; (financial systems, political systems, etc) we will agree that they individually have their own components and it's the summation of this components that makes the system, this implies that system thinking could be applicable in this kinda of systems as long as they are made up of components.

4) Technology has boosted every sector of our lives and it has the capacity to do more. Restricting it's importance to entertainment alone would be an underusing of its potentials. Engineering students infact should not need any drive to be encouraged about maximizing all it can do in shaping our world.

5) ~ Nature shows its splendid soul

~Never ceases to leave us in amazement

~And we are in love

4 0
2 years ago
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