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3 years ago

Explain the difference in the heat transfer modes of conduction and convection.

Engineering

1 answer:

LiRa [457]3 years ago

4 0

Explanation:

Conduction is the heat transfer through a stationary matter by the physical contact.

For example, the heat transferred between electric burner of stove and bottom of pan is transferred by the process of conduction.

Convection is heat transfer by macroscopic movement of the fluid. The particles of the fluid carry the current within themselves.

For example, the water is the pot is warmed overall by heat transferred by the process of convection.

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Determine the COP of a refrigerator that removes heat from the food compartment at a rate of 5160 kJ/h for each kW of power it c

Mars2501 [29]

Answer:

$COP_R=1.433\\Q_H=2.433kW$

Explanation:

Hello,

In this case, the coefficient of performance of this refrigerator is defined in terms of the removed heat and the work input as:

$COP_R=\frac{Q_{L}}{W_{in}} =\frac{5160\frac{kJ}{h}*\frac{1h}{3600s} }{1kJ/s} =1.433$

Moreover, the rate of heat rejection to the outside air tuns out:

$W_{in}=Q_H-Q_L\\Q_H=W_{in}+Q_L=1kW+5160\frac{kJ}{h}*\frac{1h}{3600s} =2.433kW$

Best regards.

3 0

3 years ago

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Which of the following is true about how the universe is expanding?

Law Incorporation [45]

B. The space between the galaxy is getting better

4 0

4 years ago

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The ???? − i relationship for an electromagnetic system is given by ???? = 1.2i1/2 g where g is the air-gap length. For current

Artemon [7]

Answer:

a) The mechanical force is -226.2 N

b) Using the coenergy the mechanical force is -226.2 N

Explanation:

a) Energy of the system:

$\lambda =\frac{1.2*i^{1/2} }{g} \\i=(\frac{\lambda g}{1.2} )^{2}$

$\frac{\delta w_{f} }{\delta g} =\frac{g^{2}\lambda ^{3} }{3*1.2^{2} }$

$f_{m}=- \frac{\delta w_{f} }{\delta g} =-\frac{g^{2}\lambda ^{3} }{3*1.2^{2} }$

If i = 2A and g = 10 cm

$\lambda =\frac{1.2*i^{1/2} }{g} =\frac{1.2*2^{1/2} }{10x10^{-2} } =16.97$

$f_{m}=-\frac{g^{2}\lambda ^{3} }{3*1.2^{2} }=-\frac{16.97^{3}*2*0.1 }{3*1.2^{2} } =-226.2N$

b) Using the coenergy of the system:

$f_{m}=- \frac{\delta w_{f} }{\delta g} =-\frac{1.2*2*i^{3/2} }{3*g^{2} }=-\frac{1.2*2*2^{3/2} }{3*0.1^{2} } =-226.2N$

8 0

3 years ago

For this assignment, you will write a program to determine the time and date corresponding to an elapsed number of seconds since

Karolina [17]

A Python program should be written to produce output that corresponds to the given hour, minute, second, day of the month, month's name, year, and day of the week's name.

present_year=2016

present_month="January"

present_date="1"

present_day="Friday"

present_hour=0

present_minute=0

present_second=0

input<-from user(seconds)//taking imput from the user using Python program

total_seconds=input

//checking with seconds

if(total_seconds<60)

present_second+=total_seconds

else

total_minutes=total_seconds/60

remaining_seconds=total_seconds-total_minutes*60

present_second+=remaining_seconds

//checking with minutes

if(total_minutes<60)

present_minute+=total_minutes

else

total_hours=total_minutes/60

remaining_minutes=total_minutes-total_hours*60

present_minute+=remaining_minutes

//checklng with hours

if(total_hours<24)

present_hour+=total_hours

else

total_days=total_hours/24

remaining_hours=total_hours-total_days*24

present_hour+=remaining_hours

//checking with days

total_weeks=total_days/7

remaining_day=total_days-total_weeks*7

switch(remaining_day)

case 1:

present_day="Friday"

case 2:

present_day="Saturday"

case 3:

present_day="Sundayday"

case 4:

present_day="Monday"

case 5:

present_day="Tuesday"

case 6:

present_day="Wedday"

case 7:

present_day="Thursday"

//checking with years

if(total_days>366)

while(total_days)

if(present_year%4==0)

total_days-=366

present_year+=1

if(present_year%4!=4)

total_days-=365

present_year+=1

if(present_year%4!=0&&total_days<365)

break;

if(present_year%4==0&&total_days<366)

break;

//checking with months and date

if(total_days<=366)

while(total_days)

if(present_month="January")

present_date++

total_days--

if(present_date==31)

present_month="February"

present_date=0

if(present_month="February")

present_date++

total_days--

if(present_date==28&&present_year%4!=0)

present_month="March"

present_date=0

if(present_date==29&&present_year%4==0)

present_month="March"

present_date=0

if(present_month="March")

present_date++

total_days--

if(present_date==31)

present_month="April"

present_date=0

if(present_month="April")

present_date++

total_days--

if(present_date==30)

present_month="May"

present_date=0

if(present_month="May")

present_date++

total_days--

if(present_date==31)

present_month="June"

present_date=0

if(present_month="June")

present_date++

total_days--

if(present_date==30)

present_month="July"

present_date=0

if(present_month="July")

present_date++

total_days--

if(present_date==31)

present_month="August"

present_date=0

if(present_month="August")

present_date++

total_days--

if(present_date==31)

present_month="September"

present_date=0

if(present_month="September")

present_date++

total_days--

if(present_date==30)

present_month="October"

present_date=0

if(present_month="October")

present_date++

total_days--

if(present_date==31)

present_month="November"

present_date=0

if(present_month="November")

present_date++

total_days--

if(present_date==30)

present_month="December"

present_date=0

if(present_month="December")

present_date++

total_days--

if(present_date==31)

present_month="January"

present_date=0

//printing present time

print present_hour:present_minute:present_second present_date present_month present_year present_day

Learn more about Python program here:

brainly.com/question/28691290

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3 0

2 years ago

During an unsteady-flow process, the amount of mass and energy entering a control volume must be equal to the amount of mass and

SSSSS [86.1K]

Answer:

False

Explanation: An unstable flow is a flow process where the properties of the flow is unstable, in this case the flow input and flow output are not equal.

Unstable flow is also known as transient flow process because the main properties of interest which includes the time of flow and the volume of the flow through the pipe is not the same so this type of low gives more concern to the person carrying out the study.

3 0

4 years ago

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