GATE ME 2015 SET-3

Question 1
For the given fluctuating fatigue load, the values of stress amplitude and stress ratio are respectively
A
100 MPa and 5
B
250 MPa and 5
C
100 MPa and 0.20
D
250 MPa and 0.20
Machine Design   Static Dynamic Loading and Failure Theories
Question 1 Explanation: 
\sigma_{a}=\frac{\sigma_{\max }-\sigma_{\min }}{2}=\frac{250-50}{2}=100 \mathrm{MPa}
\text{Stress ratio }=\frac{\sigma _{max}}{\sigma _{min}}=\frac{50}{250}=0.2
Question 2
For the same material and the mass, which of the following configurations of flywheel will have maximum mass moment of inertia about the axis of rotation OO' passing through the center of gravity.

A
A
B
B
C
C
D
D
Engineering Mechanics   Translation and Rotation
Question 2 Explanation: 
I=m r^{2}
Here for the rimmed wheel, the mass m will be most far away distribution from the axis 0-0.
\therefore \;(B) is the correct answer.
Question 3
A gear train is made up of five spur gears as shown in the figure. Gear 2 is driver and gear 6 is driven member. N_{2},N_{3}, N_{4}, N_{5} and N_{6} represent number of teeth on gears 2, 3, 4, 5, and 6 respectively. The gear(s) which act(s) as idler(s) is/are
A
Only 3
B
Only 4
C
Only 5
D
Both 3 and 5
Theory of Machine   Gear and Gear Train
Question 3 Explanation: 
Only 5
Question 4
In the figure, link 2 rotates with constant angular velocity \omega _{2}. A slider link 3 moves outwards with a constant relative velocity V _{Q/P}, where Q is a point on slider 3 and P is a point on link 2. The magnitude and direction of Coriolis component of acceleration is given by
A
2w_{2} V_{Q/P} ; direction of V_{Q/P} rotated by 90^{\circ} in the direction of w_{2}
B
w_{2} V_{Q/P} ; direction of V_{Q/P} rotated by 90^{\circ} in the direction of w_{2}
C
2w_{2} V_{Q/P} ; direction of V_{Q/P} rotated by 90^{\circ} opposite to the direction of w_{2}
D
w_{2} V_{Q/P} ; direction of V_{Q/P} rotated by 90^{\circ} opposite to the direction of w_{2}
Theory of Machine   Displacement, Velocity and Acceleration
Question 4 Explanation: 
Direction is obtained by rotating velocity vector through 90.
Question 5
The strain hardening exponent n of stainless steel SS 304 with distinct yield and UTS values undergoing plastic deformation is
A
n \lt 0
B
n = 0
C
0 \lt n \lt 1
D
n = 1
Manufacturing Engineering   Forming Process
Question 5 Explanation: 
The value of strain hardening constant (n) lies between 0 and 1

n = 0 means material is perfectly plastic solid
n = 1 means material is perfectly elastic solid
Question 6
In a machining operation, if the generatrix and directrix both are straight lines, the surface obtained is
A
cylindrical
B
helical
C
plane
D
surface of revolution
Manufacturing Engineering   Machining and Machine Tool Operation
Question 6 Explanation: 
Generatrix:- In geometry, generotrix or generator is a point, curve or surface that, when moved generates a new shape

Directrix- The path of generatrix motion is called directrix Table showing generatrix and directrix of various curves
\begin{matrix} &\text{Generatrix}& \text{Directrix}\\ \text{Cylindrical surfaces} &\text{Straight line} &\text{Fixed curve}\\ \text{Helicel surfaces} &\text{Curve} &\text{Straight line}\\ \text{Plane} &\text{Straight line} &\text{Straight line}\\ \text{Surface of revolution }&\text{Plane curve} &\text{Fixed curve}\\ \end{matrix}
Question 7
In full mould (cavity-less) casting process, the pattern is made of
A
expanded polystyrene
B
wax
C
epoxy
D
plaster of paris
Manufacturing Engineering   Casting Process
Question 7 Explanation: 
The pattern is made of expanded polystrene.

In the expanded polystyrene casting process, a sand mold is packed around a polystyrene pattern representing the metal casting to be manufactured. The pattern is not removed, and the molten metal is poured into the pattern which is vaporized from the heat of the metal. The liquid metal takes the place of the vaporized polystyrene and the casting solidifies in the sand mold.
Question 8
In the notation (a/b/c) : (d/e/f) for summarizing the characteristics of queueing situation, the letters 'b' and 'd' stand respectively for
A
service time distribution and queue discipline
B
number of servers and size of calling source
C
number of servers and queue discipline
D
service time distribution and maximum number allowed in system
Industrial Engineering   Queuing Theory and Transportation
Question 8 Explanation: 
The general form of notation is

(a/b/c) : (d/e/f)

where,
a : Probability distribution for arrival pattern
b : departure (or service time) distribution
c : No. of server within system
d : service discipline
e : Size and capacity of system
f : Size or capacity of calling population
Question 9
Couette flow is characterized by
A
steady, incompressible, laminar flow through a straight circular pipe
B
fully developed turbulent flow through a straight circular pipe
C
steady, incompressible, laminar flow between two fixed parallel plates
D
steady, incompressible, laminar flow between one fixed plate and the other moving with a constant velocity
Fluid Mechanics   Viscous, Turbulent Flow and Boundary Layer Theory
Question 9 Explanation: 
Couette flow
In fluid dynamics, couette flow is the laminar flow of a viscous fluid in the space between two parallel plates, one of which is moving relative to the other. The flow is driven by virtue of viscous drag force acting on the fluid and the applied pressure gradient parallel to the plates.
Question 10
The thermodynamic cycle shown in figure (T-s diagram) indicates
A
reversed Carnot cycle
B
reversed Brayton cycle
C
vapor compression cycle
D
vapor absorption cycle
Refrigeration and Air-conditioning   Heat Pumps and Cycles
Question 10 Explanation: 
Reversed Brayton cycle is shown in the figure.
There are 10 questions to complete.

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