GATE CE 2017 SET-2

Question 1
Consider the following simultaneous equations (with c_{1} \; and \; c_2 being constants):
3x_{1}+2x_{2}=c_{1}
4x_{1}+x_{2}=c_{2}
The characteristic equation for these simultaneous equations is
A
\lambda ^{2}-4\lambda -5=0
B
\lambda ^{2}-4\lambda+5=0
C
\lambda ^{2}+4\lambda-5=0
D
\lambda ^{2}+4\lambda+5=0
Engineering Mathematics   Linear Algebra
Question 1 Explanation: 
\begin{aligned} \left [ A \right ]&=\begin{bmatrix} 3 & 2\\ 4 & 1 \end{bmatrix} \\ \left [ A-\lambda I \right ]&=\begin{bmatrix} 3-\lambda & 2\\ 4 & 1-\lambda \end{bmatrix} \\ \left | A-\lambda I \right |&=0 \\ \left ( 3-\lambda \right )\left ( 1-\lambda \right )-8&=0 \\ 3-4\lambda +\lambda ^{2}-8&=0 \\ \lambda ^{2}-4\lambda -5&=0 \end{aligned}
Question 2
Let w=f(x,y), where x and y are functions of t. Then, according to the chain rule, \frac{dw}{dt} is equal to
A
\frac{dw}{dx}\frac{dx}{dt}+\frac{dw}{dy}\frac{dt}{dt}
B
\frac{\partial w}{\partial x}\frac{\partial x}{\partial t}+\frac{\partial w}{\partial y}\frac{\partial y}{\partial t}
C
\frac{\partial w}{\partial x}\frac{dx}{dt}+\frac{\partial w}{\partial y}\frac{dy}{dt}
D
\frac{dw}{dx}\frac{\partial x}{\partial t}+\frac{dw}{dy}\frac{\partial y}{\partial t}
Engineering Mathematics   Calculus
Question 2 Explanation: 
w=f\left ( x, y \right )
By Chain rule,
\frac{dw}{dt}=\frac{\partial w}{\partial x}\times \frac{dx}{dt}+\frac{\partial w}{\partial y}\times \frac{dy}{dt}
Question 3
Given that the scope of the construction work is well-defined with all its drawings, specifications, quantities and estimates, which one of the following types of contract would be most preferred?
A
EPC contract
B
Percentage rate contract
C
Item rate contract
D
Lump sum contract
Construction Materials and Management   
Question 3 Explanation: 
Scope of construction work is well-defined with all its drawings, specification quantities and estimates, then lump sum contract is used.
Question 4
Let G be the specific gravity of soil solids, w the water content in the soil sample,\gamma _{w} the unit weight of water, and \gamma _{d} the dry unit weight of the soil. The equation for the zero air voids line in a compaction test plot is
A
\gamma _{d}=\frac{G\gamma _{w}}{1+Gw}
B
\gamma _{d}=\frac{G\gamma _{w}}{Gw}
C
\gamma _{d}=\frac{Gw}{1+\gamma _{w}}
D
\gamma _{d}=\frac{Gw}{1-\gamma _{w}}
Geotechnical Engineering   Properties of Soils
Question 4 Explanation: 
Percentage air void line is relation between dry unit weight and water content at constant air void. Hence equation of zero air void line is
\begin{aligned} \gamma_{\mathrm{d}}&=\left(1-n_{\mathrm{a}}\right) \frac{G \gamma_{\mathrm{w}}}{1+w G} &\left(n_{\mathrm{a}}=0\right) \\ \gamma_{\mathrm{d}}&=\frac{G \gamma_{\mathrm{w}}}{1+w G} \end{aligned}
Question 5
Consider the following statements related to the pore pressure parameters, A and B:
P. A always lies between 0 and 1.0
Q. A can be less than 0 or greater than 1.0
R. B always lies between 0 and 1.0
S. B can be less than 0 or greater than 1.0

For these statements, which one of the following options is correct?
A
P and R
B
P and S
C
Q and R
D
Q and S
Geotechnical Engineering   Consolidation of Soils
Question 5 Explanation: 
Pore pressure parameter B lies in between 0 to 1 and pore pressure parameter A may be as low as -0.5 and may be as high as 3.
Question 6
Consider a rigid retaining wall with partially submerged cohesionless backfill with a surcharge. Which one of the following diagrams closely represents the Rankine's active earth pressure distribution against this wall?
A
A
B
B
C
C
D
D
Geotechnical Engineering   Retaining Wall-Earth Pressure Theories
Question 6 Explanation: 


Question 7
If a centrifugal pump has an impeller speed of N (in rpm), discharge Q (in m^{3}/s ) and the total head H (in m), the expression for the specific speed N_{s} of the pump is given by
A
N_{s}=\frac{NQ^{0.5}}{H^{0.5}}
B
N_{s}=\frac{NQ^{0.5}}{H}
C
N_{s}=\frac{NQ^{0.5}}{H^{0.75}}
D
N_{s}=\frac{NQ}{H^{0.75}}
Fluid Mechanics and Hydraulics   Hydraulic Pumps
Question 7 Explanation: 
Specific speed of pump.
N_{\mathrm{s}}=\frac{N \sqrt{Q}}{H^{3 / 4}}=\frac{N Q^{0.5}}{H^{0.75} }
Question 8
As per Noise Pollution (Regulation and Control) Rules 2000 of India, the day time noise limit for a residential zone, expressed in dB(A) L_{eq}, is
A
55
B
65
C
75
D
85
Environmental Engineering   Air and Noise Pollution
Question 9
Following observations have been made for the elevation and temperature to ascertain the stability of the atmosphere:

The atmosphere is classified as
A
Stable
B
Unstable
C
Neutral
D
Inverse
Environmental Engineering   Air and Noise Pollution
Question 9 Explanation: 
ELR_{1-2}=\frac{15.5-15}{\left ( 60-10 \right )\times 10^{-3}}=10^{\circ}C/km
ELR_{2-3}=\frac{15-14.3}{\left ( 130-60 \right )\times 10^{-3}}=10^{\circ}C/km
Since ELR\gt ALR(9.8^{\circ}C/km)
Atmosphere is unstable.
Question 10
The most important type of species involved in the degradation of organic matter in the case of activated sludge process is
A
Autotrophs
B
Heterotrophs
C
Prototrophs
D
Photo-autotrophs
Environmental Engineering   Treatment of Waste Water
Question 10 Explanation: 
Activated sludge process is designed primarily for satisfaction of carbonaceous BOD which is done by heterotrophs.
There are 10 questions to complete.

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