Write SQL queries to answer the following questions: What are the names of the course(s) that student Altvater took during the s
emester I-2018? List the names of the students who have taken at least one course that Professor Collins is qualified to teach. List the names of the students who took at least one course with ""Syst"" in its name during the semester I-2018.
1 answer:
Answer:
See explanations
Explanation:
Consider the following Venn diagram to retrieve the name of course that student Altvater took during semester I-2015.
• In above Venn diagram inner Ellipse represent the subquery part, this subquery part select the Student ID from STUDENT table.
• Second sub query is used to determine the SectionNo of all student whose studentID retrived in the first subquery
• Finally the main query displays the CourseName from COURSE table.
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Answer:
Explanation:
The question can be well structured in a table format as illustrated below:
Tensile Strength (MPa) Number- Average Molecular Weight (g/mol)
82 12,700
156 28,500
The tensile strength and number-average molecular weight for two polyethylene materials given above.
Estimate the number-average molecular weight that is required to give a tensile strength required above. Using the data given find TS (infinity) in MPa.
<u>SOLUTION:</u>
We know that :
where;
= Tensile Strength
= Tensile Strength (Infinity)
= Number- Average Molecular Weight (g/mol)
SO;
From equation (1) ; collecting the like terms; we have :
From equation (2) ; we have:
So;
Then;
Solving by L.C.M
By cross multiplying ; we have:
Collecting like terms ; we have
Dividing both sides by 15800:
A = 1695208.861
From equation (1);
Replacing A = 1695208.861 in the above equation; we have:
From equation(2);
Replacing A = 1695208.861 in the above equation; we have:
We are to also estimate the number- average molecular weight that is required to give a tensile strength required above.
If the Tensile Strength (MPa) is 82 MPa
Definitely the average molecular weight will be = 12,700 g/mol
If the Tensile Strength (MPa) is 156 MPa
Definitely the average molecular weight will be = 28,500 g/mol
But;
Let us assume that the Tensile Strength (MPa) = 181 MPa for example.
Using the same formula:
Then:
Collecting like terms ; we have:
1695208.861= 34.481
Dividing both sides by 34.481; we have:
=
Answer:
The mass flow rate of steam m=5.4 Kg/s
Explanation:
Given:
At the inlet of turbine P=10 MPa ,T=500 C
AT the exit of turbine P=10 KPa ,x=0.9
Required power=5 MW
From steam table
<u> At 10 MPa and 500 C:</u>
h=3374 KJ/Kg ,s=6.59 KJ/Kg-K (Super heated steam table)
<u>At 10 KPa:</u>
=2675.1 KJ/Kg,
=417.51 KJ/Kg
= 7.3 KJ/Kg-K ,
=1.3 KJ/Kg-K
So enthalpy of steam at the exit of turbine
h=
Now by putting the values
h= 417.51+0.9(2675.1- 417.51) KJ/Kg
h=2449.34 KJ/Kg
Lets take m is the mass flow rate of steam
So
m=5.4 Kg/s
So the mass flow rate of steam m=5.4 Kg/s