Civil Engineering - UPSC Civil Service Exam Questions - Discussion

Discussion Forum : UPSC Civil Service Exam Questions - Section 11 (Q.No. 24)
24.
Due to rise in temperature, the viscosity and unit weight of percolating fluid are reduced to 70% and 90% respectively. Other things being constant, the change in coefficient of permeability will be
20.0%
28.6%
63.0%
77.8%
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
16 comments Page 1 of 2.

Johny Sins said:   5 years ago
Taylor's equation based on Poiseuille's law for laminar flow through the circular tube is given by

k=rμe31+ec2D

Change in the coefficient of permeability.

k1 = 0.9r0.7μe31 + ecD2.
k1k = 0.90.7 * 100 = 128.57%.

change = 28.57%.

SK MURSHID said:   5 years ago
K=(90/70)* 100 = 128.6.

Change =128.6 -100=28.6
As total quantity is 100 so it subtracts by 100.
28.6 is the increase of value K,
Answer: B.

Madhu said:   6 years ago
28.6% Increased.

Rajneesh said:   6 years ago
It should be increased by 50% because.

K -Y/u.
K=90/60=1.5*100=150.
150-100=50%.

Soumya said:   6 years ago
Anybody explain in detail.

Deepak Mishra said:   7 years ago
It should be 28.6%.

Kiran Gauswami said:   7 years ago
B is the right answer.
90/70=1.286,
Then 28.6.

Dolly said:   7 years ago
I think B is correct.

Mitesh said:   7 years ago
B is Correct.

Sidd said:   7 years ago
K=unit weight of water/viscosity.

Take as k1 and k2.
There is a reduction from the 1st k(k1) and reduced one is k2.
K1/k2=(Unit wt of w/vis)1 / (unit wt of w/ vis)2.
Solving we get k1=1.286k2.
For finding the percentage (k1-k2) * 100.
Ans 28.6 per cent.


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