From the list of problems below, check all that are known to be NP-complete. You do not need to justify your answer. (Set cover)
1 answer:
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Answer:
the absolute pressure in the smaller pipe = 19.63 psi
Explanation:
Let A be the diameter of the first pipe = 3 inches
Let B be the diameter of the second pipe. = 1.5 inches
To feet (ft) ; we have
Diameter of the pipe A
Diameter of pipe B
Temperature T = 120° F = (120+ 460)°R
= 580 ° R
The pressure gage to atmospheric pressure ; we have:
where;
atmospheric pressure = 1.47 psi
pressure gage = 20 psi
To lb/ft²; we have:
4.998.6 fb/ft²
The density of carbon dioxide can be calculated by using the relation
Formula for calculating cross sectional area is
For diameter of pipe
A₁ =
A₁ = 0.04909 ft²
For diameter of pipe
A₂
A₂ = 0.012227 ft²
Using the continuity equation to determine the velocities V₁ and V₂ respectively.
For V₁
Q = A₁V₁
V₁ = Q₁/ A₁
V₁ = 1.5/0.04909
V₁ = 30.557 ft/s
For V₂
Q = A₂V₂
V₂= Q₂/ A₂
V₂ = 1.5/0.04909
V₂ = 30.557 ft/s
Finally; using Bernoulli's Equation to the flow of the carbon dioxide from the larger pipe to the smaller pipe ; we have:
Since the pipe is horizontal then;
So;
To psi;
gage
The absolute pressure in the smaller pipe can be calculated as:
Hence, the absolute pressure in the smaller pipe = 19.63 psi
Answer:
0.16 micron per day
Explanation:
Given:
The initial crack length, a₁ = 0.1 micron = 0.1 × 10⁻⁶ m
Initial tensile stress, σ₁ = 120 MPa
Final stress = 30 MPa
now from Griffith's equation, we have
where,
Gc and E are the material constants
now,
for the initial stage
........{1}
and for the final case
............{2}
on dividing 1 by 2, we get
or
a₂ = 4² × 0.1 × 10⁻⁶ m
or
a₂ = 1.6 micron
Now,
the change from 0.1 micron to 1.6 micron took place in 10 days
therefore, the rate at which the crack is growing =
or
average rate of change of crack = 0.16 micron per day