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S.No Question Option A Option B Option C Option D Answer Solution Comments Status Action
1 A body of weight w is supported by two springs as shown below. The equivalent spring constant is :
 \(\frac{1}{K_{1}}+\frac{1}{K_{2}}\) K1+K2 K1-K2 K1 K2 b Both Spring are in parallel deflection = \(δ\)
\(δ_{1}=δ_{2}\)
And \(K_{eq}=K_{1}+K_{2}\)		 Comments Active
2 In a slider-crank mechanism, the piston velocity is maximum, when: Crank is perpendicular to line of stroke. Crank and connecting rod are collinear. Crank is perpendicular to connecting rod None of the above. a Single slider crank mechanism
Velocity of piston is
\(ν_{P}=ωr (sinθ+\frac{sin2θ}{2n})\)
Where r = crank radius,
\(ω=crank speed, n=obliguity ratio\)
Velocity of slider will be max at , \(θ=90°\)
\(∴V_{max}=rω (1+0)=rω\)
When, , i.e. crank is perpendicular to the line of stroke, the velocity of slider is maximum. \(θ=90°\)		 Comments Active
3 σX + σY = σX’ +σY’ = σ1 + σ2The above relation is called independency of normal stresses constancy of normal stresses first invariant of stress all the above three d Comments Active
4 Stress and Strain are tensor of zero-order first order second order None of the above c Stress tensor
\((σ_{xx}τ_{xy}τ_{xz}τ_{yx}σ_{yy}τ_{yz}τ_{zx}τ_{zy}σ_{zz})_{3×3}\)
Strain tensor
\((ϵ_{xx}\frac{γ_{xy}}{2}\frac{γ_{xz}}{2}\frac{γ_{yx}}{2}ϵ_{yy}\frac{γ_{yz}}{2}\frac{γ_{zx}}{2}\frac{γ_{zy}}{2}ϵ_{zz})_{3×3}\)
Matrix of second order
\(σ=normal stress\)
\(Ï„=shear stress\)
\(ϵ=linear strain\)
\(γ=shear strain\)		 Comments Active
5 In a slotted lever and crank quick return mechanism used in shapers, the beginning and end of cutting stroke occurs when cranked lever are in line with each other crank is perpendicular to lever crank is horizontal lever is horizontal b In a slotted lever and crank quick return mechanism used in shapers, the beginning and end of cutting stroke occurs when crank is perpendicular to lever. Comments Active
6 A flywheel in an I.C. engine: controls the supply of fuel to the engine controls the cyclic fluctuation of speed controls the speed variation due to load All the above c A flywheel controls the speed variations caused by the fluctuation of the engine turning moment during each cycle of operation. Comments Active
7 In a mechanism having six links, the number of instantaneous centres of rotation present are 15 12 9 6 a \( N=\frac{n(n-1)}{2}=\frac{6×5}{2}=15\) Comments Active
8 A gear train, in which at least one of the gear axes is in motion relative to the frame, is known as reverted gear train non-reverted gear train epicyclic gear train none of the above c Epicyclic gear train: when the gear train is having a relative motion of axes it is called the epicyclic gear train. The axis of at least one of the gears also moves relative to the frame. Comments Active
9 If the damping factor for a vibrating system is unity, then the system is critically damped under damped over damped zero damped a The damping ratio is a system parameter, that can vary from un – damped under damped (ζ < 1) through critically damped to over damped \((ζ=c/c_{c})\) \((ζ=0)\) \((ζ=1)\) \((ζ>1)\) Comments Active
10 The maximum efficiency of a screw jack having square threads and friction angle of 30° will be 11 % 20 % 30 % 33 % d The maximum efficiency of screw jack is:
\(η=\frac{1-sin∅}{1+sin∅}=\frac{1-sin30°}{1+sin30°}\)
\(=\frac{1-\frac{1}{2}}{1+\frac{1}{2}}=\frac{1}{3}=33.33%\)		 Comments Active
11 For steady state forced vibrations, the phase lag at resonance condition is 0° 45° 80° 90° d For steady state vibration
\(\frac{ω}{ω_{n}}≫1\)
Phase angle = 180°		 Comments Active
12 Any distributed mass can be replaced by two-point masses to have the same dynamical properties, if The sum of the two masses is equal to the total mass. The combined center of mass coincides with that of the rod The moment of inertia of two point masses about perpendicular axis through their combined center of mass is equal to that of the rod All the above. d Comments Active
13 Identify the wrong statement: A mechanism is an assemblage of four or more links. A slider crank chain consists of two sliding pairs and two turning pairs. A kinematic chain requires at least four links and four turning pairs. Open pairs are those whose elements are not held together mechanically. b 1 Sliding pair and 3 turning pair. Comments Active
14 Coriolis’ component of acceleration occurs in quick return mechanism four bar mechanism slider crank mechanism none of the above a Coriolis’ component of acceleration occurs in quick return mechanism. Comments Active
15 Spur gears have/are straight teeth perpendicular to the axis. curved teeth perpendicular to the axis. not subjected to axial thrust due to tooth load subjected to axial thrust due to tooth load a \( P_{x}=axial thrust P_{y}\) Comments Active
16 The motion of a nut on a threaded bolt is Helical Plane Spherical None of the above c Helical motion Comments Active
17 Static balancing involves balancing of Forces Couples Masses All the above a Static balancing is used for force balancing and dynamic balancing is used for bot force and couple balancing. Comments Active
18 The point on the Cam with maximum pressure angle is known as the Cam center Pitch point Trace point Prime point b The pressure angle represents the steepness of cam profile is the angle between the normal to the pitch curve at a point and the direction of the follower motion. It varies in magnitude at all instants of the follower motion. Comments Active
19 Creep in belts occurs due to which one of the following: Belt and pulley surfaces are smooth Belt is thick Due to unequal tensions on the two sides of the pulley The pulley diameters are large c The motion of belt relative to driving and driven pulley due to unequal stretching of the two sides of the drive is known as creep. Comments Active
20 When teeth formed on the cones are straight, the gears are known as worm gear helical gear straight bevel spiral bevel c Comments Active
21 If the speed of the engine varies between 390 and 410 rpm in a cycle of operation, the coefficient of fluctuation of speed will be 0.01 0.03 0.05 0.07 c \( C_{S}=\frac{N_{max}-N_{min}}{M_{mesn}}=\frac{490-390}{\frac{410+390}{2}}\)
\(=\frac{20}{400}=0.05\)		 Comments Active
22 At a certain speed, revolving shafts tend to vibrate violently in transverse directions, this speed is known as Whirling speed Critical speed Whipping speed All the above d The critical speed of a shaft is also called as whirling speed. It is also defines as the speed at which a rotating shaft will tend to vibration direction if the shaft rotates in a horizontal direction. In other words, the whirling or critical speed is the speed at which resonance occurs. Comments Active
23 In free vibrations, the acceleration vector leads the displacement vector by π/3 π/2 2π/3 π d In free vibration, we know that the equation of displacement at time t is given by,
\(x(t)=Xsin(wt+∅)…………..(1)\)
Which is the equation of displacement vector.
Where X = initial displacement
W = Natural frequency
∅ = Phase different
Different this equation w.r.tt we get
X’(t) = X w cos (wt + ∅)
Which is the velocity vector again differentiating w.r.tt we get
\(X"(t)=-Xw^{2} sin⁡ (wt+∅)\)
\(=X"(t)=-Xw^{2} sin⁡ (wt+∅-π)………(2)\)
Which is the equation of acceleration vector. Comparing equation (1) and equation (2) we get all the acceleration vector leads the displacement vector by π radians or 180°.		 Comments Active
24 In a simple gear train, there is odd number of idlers. The direction of rotation of the driver and the driven gears will be same opposite depends upon the number of teeth of the gears depends upon the diameter of idlers used a In a simple gear train, there is odd number of idlers. The direction of rotation of the driver and the driven gears will be, same direction. Comments Active
25 For a safe design, a friction clutch is designed assuming uniform wear uniform pressure any one of the above None of the above a When dutch, bearing becomes old after being used for a given period, then all parts of the rubbing surfaces will not move with the same velocity.
The velocity of rubbing surfaces increase with the distance from the axis of the rotating element.
It means that wear may be different at different radii and rate of wear depends upon the intensity of pressure (P) and the velocity of rubbing surfaces (V).
It is assumed that the rate of wear is proportional to the product of intensity of pressure and velocity of rubbing surfaces.
This condition assumes that the rate of wear is uniform.
\(P×r=Constant \)
\(P=Pressure intensity\)
\(r=Radius of rotation\)		 Comments Active
26 The instantaneous centre of rotation of a circular disc rolling on a straight path is at the centre of the disc their point of contact the centre of gravity of the disc infinity b at their point of contact Comments Active
27 In a governor, if the equilibrium speed is constant for all radii of rotation of balls, the governor is said to be stable governor unstable governor inertia governor Isochronous governor d Comments Active
28 When two gear teeth are in mesh, then pure rolling occurs at the root of tooth tip of tooth pitch point flank c When pair of teeth touch at the pitch point, they have for the instant pure rolling action. At any other position they have the sliding action. Comments Active
29 When there is no slip, the power transmitted by belts is proportional to (T1 – T2) V (T1 + T2) V (T1 / T2) V (T1 – T2) / V a The power transmitted by the belt depends on the tension on the two sides and the belt speed. Let be the tension of tight side in ‘N’ and be the tension on the slack side in ‘’ and V be the speed of the belt in m/s. Then power transmitted by the belt is given by Power. \(T_{1}\) \(T_{2}\) \(N_{1}\)
\(P=(T_{1}-T_{2})V watt\)		 Comments Active
30 The minimum number of teeth which can be cut for standard tooth for a given pressure angle ‘φ’ the following sin2 φ/2 2/sin2 φ 2 sin2 φ 2 sin2φ b \( Z_{min}=\frac{2}{sin^{2}ϕ}\)
\(Ï•=pressure angle\)		 Comments Active
31 Which one of the following is not an example of higher pair? Disc Cam and roller follower Spur Gear meshing teeth Ball Bearing Bush Bearing d In bush bearing there is surface contact hence lower pair. Disc command roller follower have point contact i.e. higher pair.
Meshing spur gear have line contact i.e. higher pair.
Ball bearing have point contact i.e. higher pair.		 Comments Active
32 Which of the following brakes is commonly used in motor cars? Band Brake Shoe Brake Internal expanding Shoe Brake All the above c Internal expanding shoe brake. Comments Active
33 What does the elasticity of material enable it to do? Regain the original shape after the removal of applied force. Draw into wires by the application of force. Resist fracture due to high impact. Retain deformation produced under load permanently. a Draw into wires by the application of force due to plasticity.
Resist fracture due to high impact is due to toughness. Retain deformation produced under load permanently is due to plasticity.		 Comments Active
34 Which of the following has no unit? Kinematic viscosity Strain Surface Tension Bulk Modulus b Strain \(=\frac{∆l(m)}{li(m)}\) Comments Active
35 The relation among the elastic constants E, G and K is E= \(\frac{KG}{9K+G}\) E= \(\frac{9KG}{K+G}\) E= \(\frac{9KG}{K+3G}\) E= \(\frac{9KG}{3K+G}\) d \( E=\frac{9KG}{3K+G}\) Comments Active
36 The unit of modulus of elasticity is same as those of stress, strain and pressure stress, pressure and modulus of rigidity stress, force and modulus of rigidity stress, force and pressure c All quantities have some units as N/mm2 or MPa. Comments Active
37 The theory applicable for the analysis of thick cylinders, is Lame’s theory Rankine’s theory Poisson’s theory Caurbon’s theory a For thick cylinder
\(Radial stress, σ_{r}=A-\frac{B}{r^{2}}\)
\(Circumferial or hoop stress σ_{n}=A+\frac{B}{r^{2}}\)
These two equations are called Lame’s equation. The constants A and B are obtained from the boundary conditions		 Comments Active
38 The ratio of hoop stress to longitudinal stress in thin walled cylinders is 1 1/2 2 1/4 b Hoop or circumferential stress.
\(σ_{n}=\frac{Pd}{2t}\)
Longitudinal stress
\(σ_{l}=\frac{Pd}{4t}\)
The ratio of longitudinal to hoop stress.
\(=\frac{\frac{Pd}{4t}}{\frac{Pd}{2t}}=0.5\)		 Comments Active
39 When a body is subjected to direct tensile stresses (σx and σy) in two mutually perpendicular directions, accompanied by a simple shear stress τxy, then in Mohr’s circle method, the circle radius is taken as (σx – σy)/2 + τxy (σx + σy)/2 + τxy \(\frac{1}{2}(σ_{x}-σ_{y})^{2}+4τxy 2 \) \(\frac{1}{2}(σ_{x}+σ_{y})^{2}+4τxy2\) c Radius of Mohr’s circle = \(τ_{max}\)
\(=\frac{1}{2}(σ_{x}+σ_{y})^{2}+4τxy2\)
\(D=σ_{x}-σ_{y}\)
\(R=\frac{σ_{x}-σ_{y}}{2}\)
\(C=σ_{y}+R=\frac{σ_{x}+σ_{y}}{2}\)		 Comments Active
40 Slenderness ratio has dimension of cm cm–1 cm2 None d \( Slenderness Ratio=\frac{length}{radius of gyration}\)
So Sr is dimensionless		 Comments Active
41 A body is subjected to two unequals like direct stresses σ1 and σ2 in two mutually perpendicular planes along with simple shear stress q

Which among the following is then a wrong statement ?		 The principal stresses at a point are
P1P2 = ± \(\frac{σ_{1}-σ_{2}}{2}\) \((\frac{σ_{1}-σ_{2}}{2})^{2}+ q2 \)		 The position of principal planes with the plane of stress σ1, are
θ1 = θ2= θ1+45° \(\frac{1}{2}tan^{-1}\frac{σ_{1}-σ_{2}}{2} ;\)		 Maximum shear stress is (σt)max =
± \((\frac{σ_{1}-σ_{2}}{2})^{2}+ q2 \)		 Planes of maximum shear are inclined at 45° to the principal planes. b \( θ_{2}=θ_{1}+90° (Should be)\) Comments Active
42 Choose the correct relationship in the given statements of Assertion (a) and Reason (R).
Assertion (A): A plane state of stress does not necessarily result into a plane state of strain.
Reason (R): Normal stresses acting along X and Y directions will also result into strain along the Z-direction.
Code:		 Both (A) and (R) are true. (R) is the correct explanation of (A). Both (A) and (R) are true. (R) is not the correct explanation of (A). (A) is true, but (R) is false. (A) is false, but (R) is true. a Comments Active
43 The outside diameter of a hollow shaft is twice its inside diameter. The ratio of its torque carrying capacity to that of a solid shaft of the same material and the same outside diameter is 15/16 3/4 1/2 1/16 a For hollow shaft
\(\frac{D_{i}}{D_{o}}=\frac{1}{2}=C\)
For solid shaft
\(D_{s}=D_{o}\)
For same material of both shafts.
\(Ï„_{S}=Ï„_{H}=Ï„\)
Now from torsion equation
\(\frac{T}{J}=\frac{GO}{L}=\frac{Ï„}{R}\)
\(T_{S}=Ï„.\frac{J}{R}=\frac{Ï€DS3}{16}.Ï„\)
For hollow shaft
\(T_{H}=\frac{\frac{Ï„.Ï€(Do4-Di4}{32}}{\frac{D_{o}}{2}}\)
\(=\frac{\frac{Ï€Do3}{16} (1-C^{4})Ï„}{Ï€DS3 Ï„}\)
\(=1-\frac{1}{16}=\frac{15}{16}\)		 Comments Active
44 A beam of Z-section is called a doubly symmetric section beam singly symmetric section beam a-symmetric section beam none of the above c A beam of Z-section is called a symmetric section beam. Comments Active
45 Which one of the following will result into a constant strength beam? The bending moment at every section of the beam is constant. Shear force at every section is same. The beam is of uniform section over its whole length. The ratio of bending moment to the section modulus for every section along the length is same. d Beams have uniform cross – section throughout their length. When they are loaded, there is a variation in bending moment from section to section along the length. The stress in extreme outer fibre (top and bottom) also vary from section to section along their length.
The extreme fibers can be loaded to the maximum capacity of permissible stress (say but they are loaded to less capacity. Hence in beams of uniform cross – section there is a considerable waste of materials when a beam is suitably designed such that the extreme fibres are loaded to the maximum permissible stress by varying the cross – section it will be known as a beam of uniform strength. \(P_{max})\) \(P_{max}\)		 Comments Active
46 A uniform metal bar of weight ‘W’, length ‘L’, cross-sectional area ‘A’ is hung vertically with its top end rigidly fixed. Which section of the bar will experience maximum shear stress? Top-section Mid-section Bottom-section L/3 from top a At top section Comments Active
47 Two strips of equal lengths and widths are joined together by two rivets, one at each end. One strip is of copper and the other of steel. Now, the temperature of this assembly is lowered, the rivets will undergo. Bending Single shear Double shear Both (a) & (b) above d \(Y_{1} Comments Active
48 Two simply supported beams of equal lengths, cross sectional areas, and section moduli, are subjected to the same concentrated load at its mid-length. One beam is made of steel and other is made of Aluminium. The maximum bending stress induced will be in Steel beam Aluminium beam Both beams of equal magnitude The beams according to their Elastic Moduli magnitude. c \( \frac{M_{b}}{I}=\frac{σ_{b}}{y}=\frac{E}{R}\)
\(σ_{b}=\frac{M_{b}}{I/y}=\frac{M_{b}}{Z}\)
∵ Z is same for both beams; so will be same. \(σ_{b}\)
By as then R (Radius of curvature) will be different. \(σ_{b}∝E\)		 Comments Active
49 The bending moment diagram for a simply supported beam AB of length ‘L’ is shown below

CD1 = CD2 = M / 2
Sagging moment: positive
Hugging moment: negative
What is the load acting on beam AB?		 An upward concentrated load M/2at (C) A downward concentrated load M/2 at (C) An anticlockwise moment ‘M’ at C A clockwise moment ‘M’ at (C) c Comments Active
50 Match List – I with List – II and select the correct answer using the code given below the lists.
List – I List – II
(Characteristic) (Member)		 1 2 3 4 3 4 2 1 4 1 2 3 2 3 1 4 b Kernel is the portion of a cross section of a structural member in which nature of stress is same as applied load on the cross – section.
Tie remain under tension while street remains always in compression in a roof – truss. Section modulus is defined as the ratio of moment of inertia to the radius of the shaft or the distance from the neutral axis to the outer fibers.
Z = I/y
Stiffness is the rigidness of any object or material.		 Comments Active
51 A long column of length (L) with both ends hinged, is to be subjected to axial load. For the calculation of Euler’s buckling load, its equivalent length is L/2 L/√2 L 2L c Repeated
\(Le=L\)		 Comments Active
52 Two cantilever steel beams of identical length and of rectangular section are subjected to same point load at their free end. In one beam, the longer side of section is vertical, while in the other, it is horizontal. Beams defect at free end equally irrespective of their disposition. more in case of longer side vertical. less in case of longer side horizontal. less in case of longer side vertical. b Contraction occur during lowering temperature = C
\(C_{cu}>C_{steel}\)
\(Cu-Tensile\)
\(Steel-compressive\)
\(-Single shear\)		 Comments Active
53 One end of a metallic rod is fixed rigidly and its temperature is zero stress tensile stress compressive stress None of the above a The stress developed will be zero. Though strain will be there but this strain will not generate any stress as there is no restriction to this deformation. Comments Active
54 In a static tension tests of a low carbon steel sample, the gauge length affects yield stress ultimate tensile stress percentage elongation percentage reduction in cross-sectional area c \( % elongation=\frac{Final gauge (L)-Initial g.L}{initial gauge L}\) Comments Active
55 Consider the following statements:
1. An I.C. engine transforms chemical energy into mechanical energy.
2. A compressed spring possess potential energy.
3. A football rolling on the ground performs plane motion.
4. Strain gauges are used to measure torque.
Following are the correct statements:		 1 and 2 only 2 and 3 only 3 and 4 only 1, 2 and 4 only a Football can move in all three axes, strain gauges are used to measure strain or force. Comments Active
56 A cylindrical shell of diameter 200 mm and wall thickness 5 mm is subjected to internal fluid pressure of 10 N/mm2. Maximum shearing stress induced in the shell in N/mm2, is 50 75 100 200 c Given
\(P=10 N/mm^{2}\)
\(d=200 mm\)
\(t=5 mm\)
\(Ï„_{max}=\frac{pd}{4t}\)
\(=\frac{10×200}{4×5}\)
\(=100 N/mm^{2}\)		 Comments Active
57 In theory of simple bending of beams, which one of the following assumptions is incorrect? Elastic modulus in tension and compression are same for the beam materials. Plane sections remain plane before and after bending. Beam is initially straight. Beam material should not be brittle. d Assumption of simple bending
* Only pure bending can occur there’s no shear force, torsion nor axial load.
* We consider isotropic or orthotropic homogeneous material.
* Only linear elasticity (up to proportionality limit) is analyzed.
* Initially, there’s no deformation and there’s no varying cross section.
* Beam is symmetrical in the plane along which bending occurs.
* Cross – section of the beam is still plane after (and during) bending.		 Comments Active
58 Torsional rigidity of a solid cylindrical shaft of diameter ‘d’ is proportional to d d2 d4 1 / d2 c Torsion equation
\(\frac{T}{J}=\frac{τ}{r}=\frac{Gθ}{L}\)
Torsional rigidity is also defined as torque per unit angular twist
\(GJ=\frac{T}{θ/L}\)
\(=G*\frac{Ï€}{32}d^{4}\)		 Comments Active
59 If the Mohr’s circle for a state of stress becomes a point, the state of stress is Pure shear state of stress Uniaxial state of stress Identical principal stresses None of the above c Mohr’s circle for a state of stress becomes a point, for identical principal stresses. Comments Active
60 A tension member with a cross-sectional area of 30 mm2 resists a load of 60 kN. What is the normal stress induced on the plane of maximum shear stress? 2 kN/mm2 1 kN/ mm2 4 kN/ mm2 3 kN/ mm2 b occurs at a plane which makes 45° angle with loading or applied stress direction. \( τ_{max} \)
Along P. stress.
\(σ_{x}=\frac{P}{C/S Area}=\frac{60}{30}=2 KN/m^{2}\)
Now, As we know
Normal stress
\(σ_{n}=\frac{σ_{x}+σ_{y}}{2}+(\frac{σ_{x}-σ_{y}}{2})cos 2θ\)
Here \(σ_{y}=0\)
\(θ=45°\)
\(σ_{n}=\frac{σ_{x}}{2}=\frac{2}{2}=1 KN/mm^{2}\)		 Comments Active
61 To express stress-strain relations for a linearly elastic, homogeneous, isotropic material, minimum number of material constants needed are Two Three Four One a Material
No. of independent elastic constant
Isotropic
2
Orthotropic
9
Anisotropic
21		 Comments Active
62 A metallic cube is subjected to equal pressure (P) on its all the six faces. If ∈v is volumetric strain produced, the ratio P/∈v is called Elastic modulus Shear modulus Bulk modulus Strain-Energy per unit volume d \( Bulk modulus=\frac{Normal stress}{Volumetric strain}\) Comments Active
63 In a stressed field, the change in angle between two initially perpendicular lines is called Normal strain Shear strain Principal strain Poisson’s ratio b \(ϕ=shear strain\) Comments Active
64 A beam is of rectangular section. The distribution of shearing stress across a section is Parabolic Rectangular Triangular None of the above a \(Ï„_{max}=\frac{3}{2} Ï„_{avg}\) Comments Active
65 In a loaded beam, the term represents \(\frac{dm}{dx}\) Deflection at a section Slope at a section Intensity of loading at a section Shear force at a section d \( \frac{dM}{dx}=Shear force (F)\)
\(\frac{dF}{dx}=load intensity (ω)\)		 Comments Active
66 A body is moving with a velocity 1 m/s and a force F is needed to stop it within a certain distance. If the speed of the body becomes three times, the force needed to stop it within the same distance would be 1.5 F 3.0 F 6.0 F 9.0 F d Work needed to stop the body at a distance. Let x, will be against the body’s energy, which is nothing but available kinetic energy in moving body.
\(F.x=\frac{1}{2} mv^{2}\)
\(v=1\frac{m}{s}⇒F.x=\frac{1}{2} m\)
now \(net v=3m/s\)
\(F:x=\frac{1}{2}m×3^{2}=\frac{9}{2}m\)
\(now \frac{F.x}{F:x}=\frac{1/2 m}{9/2 m}=\frac{1}{9}\)
\(F^{'}=9F\)		 Comments Active
67 A 44 N block is thrust up a 30° inclined plane with an initial speed of 5 m/sec. It travels a distance of 1.5 m before it comes to rest. The frictional force acting upon it would be 18.3 N 15.3 N 12.3 N 9.3 N b For (a)
\(V^{2}=u^{2}+2as\)
\(0=5^{2}-2a×1.5\)
\((-) Retardation \)
\(a=8.33 m/s^{2}\)
\(N=mg cos 30\)
\(ma=mg sin 30+μN\)
Solve these and get \(μN=15N\)		 Comments Active
68 Which one of the following is a scalar quantity? Force Displacement Speed Velocity c Speed have only magnitude not direction. Comments Active
69 Which one of the following is not an example of plane motion? Motion of a duster on a black board. Motion of ball point of pen on the paper. Motion of a cursor on the computer screen. Motion of a nut on a threaded bolt. d Motion of a nut on a threaded bolt is not a plane motion. Comments Active
70 A projectile on a level ground will have maximum range if the angle of projection is 30° 45° 60° 75° b Range
\(R=\frac{u^{2}sin2θ}{g}\)
\(R_{max}=\frac{u^{2}}{g} ∴sin 2θ=1=sin 90°\)
\(∴θ=45°\)		 Comments Active
71 When a body is thrown up at an angle of 45° with a velocity of 100 m/sec, it describes a parabola. Its velocity on point of return down will be zero 50 m/sec 100/ m/s \(2\) 100 m/sec \(2\) c \(\) \(u_{x}=u cos θ=100 cos 45°\)
\(u_{y}=u sin θ=100 sin 45°\)
Now
\(V^{2}=u^{2}+2gh\)
\(h=0 at point P\)
For vertical displacement
\(u^{2}py=(\frac{100}{2})^{2} \)
\(u^{2}py=\frac{100}{2}=70.7 m/s\)
∵ Range \(R=\frac{u^{2} sin 2θ}{g}\)
For \(R_{max}=sin 2θ=1=sin 90°\)
\(θ=45°\)		 Comments Active
72 Dynamic friction as compared to static friction is less same more None of the above a \(μ_{Static}>μ_{dynamic}\) Comments Active
73 If the sum of all the forces acting on a moving object is zero, the object will continue moving with constant velocity accelerate uniformly change the direction of motion slow down and stop a Here acceleration \(a=0\) Comments Active
74 Poison’s ratio is the ratio of Lateral stress to longitudinal stress Lateral stress to longitudinal strains Lateral strain to longitudinal strain Shear stress to shear strain c Poisson’s Ratio
\(ν=\frac{Lateral strain}{Longitudnal strain}\)		 Comments Active
75 Polar moment of inertia of an equilateral triangle of side ‘x’ is given by \(\frac{x^{4}}{64}\) \(\frac{x^{4}}{163}\) \(\frac{x^{4}}{32}\) b \( G=x, y\)
\(x=x/2, \) \(y=h/3\)
\(A=\frac{hx}{2}, I_{xx}=\frac{xh^{3}}{36}\)
\(I_{yy}=\frac{hx^{3}}{48}\)
\(∴I_{zz}=\frac{xh}{144}(4h^{2}+3:x^{2})\)
\(∵h=\frac{3}{2} x\)
\(∴I_{zz}=\frac{xh}{144} (4.\frac{31x^{2}}{4}+3x^{2})\)
\(=\frac{3}{48}x^{4}\)
\(=\frac{3}{483} x^{4}\)
\(=\frac{1}{163} x^{4}\)		 Comments Active
76 The unit of energy in S.I unit is Dyne Watt Newton Joule d The SI unit of energy is same as that of work, which is joule (J). Comments Active
77 The loss of kinetic energy, during inelastic impact of two bodies having masses m1 and m2, which are moving with velocity ν1 and ν2 respectively, is given by (v1-v2)2 \(\frac{m_{1}m_{2}}{2(m_{1}+m_{2})}\) (v1-v2)2 \(\frac{2(m_{1}+m_{2})}{m_{1}m_{2}}\) (v1 2-v2 2) \(\frac{m_{1}m_{2}}{2(m_{1}+m_{2})}\) (v1 2-v2 2) \(\frac{2(m_{1}+m_{2})}{m_{1}m_{2}}\) a Loss of K.E.
\(∆E=\frac{m_{1}m_{2}}{2(m_{1}+m_{2})}(V_{1}-V_{2})^{2}\)		 Comments Active
78 A thin circular ring of mass 100 kg and radius 2 m resting on a smooth surface is subjected to a sudden application of a tangential force of 300 N at a point on its periphery. The angular acceleration of the ring will be 1.0 rad/sec2 1.5 rad/ sec2 2.0 rad/ sec2 2.5 rad/ sec2 b \( ∵F=ma\)
And linear acceleration
\((a)=r∝\)
\(∝=angular acceleration \)
\(r=radius of ring\)
\(∴a=2∝\)
\(F=300=100×2∝\)
\(∝=1.5 Rad/s^{2}\)		 Comments Active
79 A spring scale reads 20 N as it pulls a 5.0 kg mass across a table. what is the magnitude of the force exerted by the mass on the spring scale ? 4.0 N 5.0 N 20.0 N 49.0 N c Spring scale always reads weight or force.
Force on spring by mass will be equal to reading of scale = 20 N \(∴\)		 Comments Active
80 Choose the correct relationship between the given statements of Assertion (a) and Reason (R).
Assertion (A): A dynamically system of multiple rotors on a shaft can rotate smoothly at the critical speeds of the system.
Reason (R): Dynamic balancing eliminates all the unbalanced forces and couples from the system.
Code:		 Both (A) and (R) are true. (R) is the correct explanation of (a). Both (A) and (R) are true. (R) is not the correct explanation of (a). (A) is true, but (R) is false. (A) is false, but (R) is true. b Comments Active
81 If the period of oscillation is to become double, then the length of simple pendulum should be doubled. the length of simple pendulum should be quadruple(d) the mass of the pendulum should be doubled. the length and mass should be doubled. b Time period
\(T=2Ï€\frac{L}{g}\)
\(T_{1}=T\)
\(T_{2}=2T\)
Now
\(\frac{T_{1}}{T_{2}}=\frac{T}{2T}=\frac{2Ï€L_{1}/g}{2Ï€L_{2}/g}\)
\(\frac{1}{2}=\frac{L_{1}}{L_{2}}\)
\(L_{2}=4L_{1}\)		 Comments Active
82 A motor boat whose speed in still water is 15 km/hr goes 30 km downstream and comes back in a total time of four and half hours. The stream has a speed of 3 km/hr 4 km/hr 5 km/hr 6 km/hr b Time period \(T=2Ï€ \frac{L}{g}\)
\(if T becomes 2T\)
\(2T=2Ï€\frac{L^{'}}{g}\)
\(\frac{2T}{T}=\frac{L^{'}/g}{L/g}=\frac{L^{'}}{L}\)
\(L^{'}=4L\)		 Comments Active
83 The escape velocity on the surface of the earth is 11.2 km/s 8.2 km/s 3.2 km/s 1.2 km/s a Escape velocity
\(v_{e}=\frac{2 G M_{earth}}{R_{earch}}\)
\(M=Mass\)
\(R=Radius \)
Now \(g=\frac{G M_{earth}}{R^{2} earth}\)
Now \(v_{e}=2g R_{earth}\)
\(=2×9.81×6.378×10^{3}\)
\(=11186.436 m/s\)
\(=11.2 km/sec\)		 Comments Active
84 If T1 and T2 are the initial and final tensions of an elastic string and x1 and x2 are the corresponding extensions, then the work done is (T2 +T1) (x2 - x1) (T2 -T1) (x2 + x1) (T2 -T1) (x2 + x1)/2 (T2 +T1) (x2 - x1)/2 d Strain energy in spring = \(\frac{1}{2} kx^{2}\)
\(=\frac{1}{2}\frac{w}{x}.x^{2}=\frac{1}{2}w.x\)
- This energy will come from work done on spring
\(W=load\)
\(K=stiffness \)
\(x=deflection\)
\(Stored energy=\frac{1}{2}×total tension ×displacement \)
\(=\frac{1}{2}(T_{1}+T_{2})(x_{2}-x_{1})\)		 Comments Active
85 A train crosses a tunnel in 30 second’s time. The speed of the train at entry and at exit from the tunnel are 36 and 54 km/hour respectively. If acceleration remains constant, the length of the tunnel is 350 m 360 m 375 m 400 m c \( V_{inlet}=36 km/hr\)
\(=36×\frac{5}{18}=10 m/s\)
\(V_{outlet}=54 km/hr =54×\frac{5}{18}\)
\(=15 m/s\)
\(t=30 sec\)
Now \(V_{0}=v_{i}+at\)
\(15=10+a×30\)
\(a=\frac{5}{30}=\frac{1}{6} m/s^{2}\)
Now \(S=ut+\frac{1}{2}at^{2} \)
\(S=10×30+\frac{1}{2}×\frac{1}{6}×30×30\)
\(=375 m\)		 Comments Active
86 If a force of 30 N is required to move a mass of 35 kg on a flat surface horizontally at a constant velocity, what will be the coefficient of friction? 0.067 0.087 0.098 0.092 b \( μ=\frac{F}{N}=\frac{applied force}{Normal reaction}\)
\(=\frac{30}{35×10} ∵N=35g=35×10\)
\(=0.086\)		 Comments Active
87 Choose the correct relationship between the given statements of Assertion (a) and Reason (R).
Assertion (A): Only axial forces act in members of roof trusses.
Reason (R): Truss members are welded together.
Code:		 Both (A) and (R) are true. (R) is the correct explanation of (A). Both (A) and (R) are true. (R) is not the correct explanation of (A). (A) is true, but (R) is false. (A) is false, but (R) is true. c Only axial force acts on truss members truss members are generally bolted or riveted. Comments Active
88 Varignon’s theorem is related to Principle of moments Principle of momentum Principle of force Principle of inertia a Varignon’s theorem states that moment of a force about any point is equal to the sum of the moments of the components of that force about the same point. Comments Active
89 According to the Newton’s law of gravitation, the force of attraction, between the bodies of masses m1 and m2 situated at a distance ‘d’ apart, is given by F =G \(\frac{m_{1}m_{2}^{2}}{d^{2}}\) F =G \(\frac{m_{2}m_{1}^{2}}{d^{2}}\) F =G \(\frac{m12 m22 }{d^{2}}\) F =G \(\frac{m_{1}m_{2}}{d^{2}}\) d \( F=\frac{Gm_{1}m_{2}}{d^{2}}\) Comments Active
90 Four forces P, 2P, 3 P & 4P act along the sides of a square, taken in order. The resultant force is zero 5P 2P \(2\) 2P c With unit vector in x – direction and in y – direction
Force vector in x – direction
\(pi,-3pi\)
Force vector in y – direction
\(2pj ̂, -4pj\)
Net force = \(pi-3pi+2pj-4pj\)
\(=-2pi-2pj\)
Magnitude = \((2p)^{2}+(2p)^{2}\)
\(=8p^{2}=22p\)		 Comments Active
91 The relationship, between number of joints (J), and the number of members (m), in a perfect truss, is given by m = 3j – 2 m = 2j – 3 m = j – 2 m = 2j – 1 b \(\) \(m=2j-3 (Perfect)\)
\(m>2j-3 (Redundant)\)
\(m<2j-3 (Deficient)\)		 Comments Active
92 Two equal and mutually perpendicular forces of magnitude ‘P’, are acting at a point. Their resultant force will be P , at an angle of 30° with the line of action of any one force. \(2\) P , at an angle of 45° with the line of action of each force. \(2\) 2P , at an angle of 45° with the line of action of each force. \(2\) Zero b Use law of Parallelogram
\(θ+θ=90°\)
Use \(R=P^{2}+P^{2}=P2\)
\(tanθ=\frac{P}{P}=1 \)
\(∴θ=45°\)		 Comments Active
93 For truss as shown below, the forces in the member AB and AC are
 Tensile in each Compressive in each Compressive and Tensile respectively Tensile and Compressive respectively c Moment about B
\(70×1.5-F_{AC}×3 sin 60°=0\)
\(F_{AC}=\frac{70×1.5×2}{3×3}=+ve (tensile)\)
Moment about C
\(70×Ac+F_{AB}×CC^{'}=0\)
\(F_{AB}=-70×\frac{AC}{CC^{'}}\)
\(=-ve (compressive)\)		 Comments Active
94 In the analysis of truss, the force system acting at each pin is concurrent but not coplanar. is coplanar and concurrent. is coplanar and non-concurrent. does not satisfy rotational equilibrium. b At joint A – Coplanar and concurrent forces act Comments Active
95 One end of a uniform ladder, of length L and weight W, rests against a rough vertical wall and the other end rests on rough horizontal ground. The coefficient of friction f is same at each end. The inclination of ladder when it is on the point of slipping is \(tan^{-1}(\frac{1-f^{2}}{2f})\) \(tan^{-1}(\frac{1+f^{2}}{2f})\) \(tan^{-1}(\frac{2f}{1+f^{2}})\) \(tan^{-1}(\frac{2f}{1-f^{2}})\) a \( \frac{ΣM=0}{W.\frac{Lcosθ}{2}}\)
\(-N_{2}Lsin θ\)
\(-μN_{2}3L cos θ\)
\(\frac{ΣH=0}{μN_{1}=N_{2}}\)
\(\frac{ΣV=0}{N_{1}+μN_{2}=W}\)
By solving these, three equation and eliminating and \(N_{1}\) \(N_{2}\)
will come as \(θ\)
\(θ=tan^{-1}(\frac{1-μ^{2}}{2μ})\)
Take \(μ=f\)		 Comments Active
96 A rigid body is subjected to non-coplanar concurrent force system. If the body is to remain in a state of equilibrium, then ∑Fx= ∑Fy = ∑Fz = 0 ∑Mx = ∑My = 0 ∑My = ∑Mz = 0 None of the above a Example for non – coplanar concurrent forces - Tripod Comments Active
97 A body subjected to coplanar non-concurrent forces will remain in a state of equilibrium if ∑Fx = 0 ∑Fy = 0 ∑M = 0 All the above three d Example of coplanar non – concurrent forces – forces in a beam Comments Active
98 The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as Limiting friction Static friction Dynamic friction Coefficient of friction a When one body is just on the point of sliding over the other body, the maximum force of friction is being exerted, this is called the limiting friction. Comments Active
99 In the following figure, the tension in the rope AC is
 17.32 N 56.60 N 169.90 N 113.20 N c Lami’s theorem
\(\frac{T_{1}}{sin 120°}=\frac{W}{sin 150°}=\frac{T_{2}}{sin90°}\)
\(\frac{T_{1}}{sin(90+30)}=\frac{10×9.8}{sin (90+60)}\)
\(\frac{T_{1}}{cos 30}=\frac{98}{cos 60}\)
\(T_{1}=\frac{98×3}{2×\frac{1}{2}}\)
\(T_{1}=169.74 N\)		 Comments Active
100 Identify the pair which has same dimensions: Force and power Energy and work Momentum and energy Impulse and momentum b \(\) \(Force-MLT^{-2} (N)\)
\(Power-ML^{2}T^{-3} (\frac{N-m}{S})\)
\(Energy-ML^{2}T^{-2}(N-m)\)
\(Work-ML^{2}T^{-2} (N-m)\)
\(Momentum-MLT^{-2} (kg-m/s)\)
\(Energy-ML^{2}T^{-2} (N-m\)
\(Impulse-MLT^{-3} (N-s)\)
\(Momentum-MLT^{-2} (kg-m/s)\)		 Comments Active
101 The difference between Graphite and Diamond is that Diamond is transparent while Graphite is opaque. Diamond is insulator while Graphite is conductor. Diamond has all primary bonds while Graphite has three primary and one secondary bonds. All the above d These two materials are known as polymorphous and chemically identical but physically are completely different. Comments Active
102 Super conductivity is that state of a material at which it electrical resistance becomes zero. becomes infinite. starts showing a change. stops being affected by temperature change. a This is the property of material by which it attains zero electrical resistance at temperature lower than 20K. Comments Active
103 Which statement is wrong about diamagnetic materials? Their susceptibility is positive. Their permeability is less than one. Super-conductors are diamagnetic They repel the external magnetic flux. a Properties of diamagnetic materials
* These are always repelled by a magnet
* The relative permeability is slightly less to that of unity
* Magnetic susceptibility is negative and small
* Superconductors are strongly diamagnetic		 Comments Active
104 Which of the following charts indicates variability of variability within the collected samples? X-chart σ chart c chart u chart a A R or X chart is a chart which uses sample ranges to calculate its centre line and control charts. So it only measures within sample variability i.e. the instantaneous variability at a given time. Comments Active
105 The mathematical technique for finding the best use of limited resources of a company in the optimum manner is known as Value analysis Network analysis Linear programming Queuing theory c Linear programming uses a mathematical or graphical technique to find the optimal way to use limited resources. Comments Active
106 Annual demand for a product, costing Rs 100 per Qpiece, is 900. Ordering cost per order is Rs 100 and the holding cost is Rs 2 per unit per year. The economic order quantity is 200 300 400 500 b \( EOQ=\frac{2DCo}{Cn}\)
\(=\frac{2×900×100}{2}=300 Rs\)		 Comments Active
107 In linear programming problem, the shadow price is the value assigned to one unit capacity the maximum cost per unit item the lowest sale price None of the above b A shadow price of a resource constraint in linear programing is usually defined as the maximum price which should be pair to obtain an additional unit of resource. Comments Active
108 Group ‘C’ items constitute the following percentage of items in ABC analysis: 10 20 50 70 d 70% - C Comments Active
109 In the model M/M/I : ∞/FCFS with utilization factor ρ, the expected line length is equal to 1 – ρ 1/(1 – ρ) ρ/ (1 – ρ) ρ2 / (1 – ρ) d \(L_{e}=\frac{ρ^{2}}{1-ρ}\)
\(ρ=Utilisation factor\)		 Comments Active
110 In an m × n transportation problem, the maximum number of basic variables is m + n m – n m + n – 1 m + n + 1 c \( m+n-1=variables\) Comments Active
111 An assembly activity is represented in an operation process chart by the symbol ∼ A o ± c the assembly activity is represented on an Operation Process Chart by the symbol 'O'. Comments Active
112 Which type of layout is preferred in order to avoid excessive multiplication of facilities? Process layout Product layout Fixed position layout Cellular manufacturing a Process layouts are layout that group resources based on similar processes or functions this type of layout is seen in companies with intermittent processing systems without enlarging the operations. Comments Active
113 When order quantity increases, the ordering cost will increase decrease remains same None of the above b Economic order quantity is that size of the order which helps in minimizing the total annual cost of inventory in the organization.
When the size of order increases, the ordering costs (cost of purchasing, inspecting etc. will decrease whereas the inventory carrying costs (costs of storage, insurance etc. will increase.		 Comments Active
114 If P = % activity and A = limit of accuracy in work sampling. The number of observations at a confidence level of 95% is given by \(\frac{(1-P)}{A^{2}P}\) \(\frac{4(1-P)}{A^{2}P}\) \(\frac{3(1-P)}{A^{2}P}\) d Comments Active
115 The probability law used for calculating the control limits of ‘P’ chart is Binomial Poisson Normal Exponential a A P- chart is used in statistical quality control to graph proportions of defective items. The chart is based on the binomial distribution, each item on the chart has only two possibilities: pass or fail. Comments Active
116 Which of the following is true about the initial basic feasible solution in simplex method ? It is an optimal solution. All basic variables are zero. Solution is not possible. Any one basic variable in zero a A basic feasible solution (BFS) is a solution with a minimal set of non – zero variables. If there exists an optimal solution then there exists an optimal BFS. Comments Active
117 BEP indicates the recovery of variable costs only both fixed and variable costs fixed cost only both fixed and variable costs along with margin of profit b Break – even analysis tells you how many units of a product must be sold to cover the fixed and variable costs of production. Comments Active
118 In ABC analysis, ‘A’ items are responsible to share approximately the following percentage of cost : 80 60 40 20 a A’s cost % - 70%
B’s cost % - 20%
C’s cost % - 10%		 Comments Active
119 ABC analysis is used in Job analysis Production Schedule Inventory Control Simulation c ABC analysis is a tool that allows companies to divide their inventory or customers into groups based on their respective values to the company.  Comments Active
120 The leaving basic variable in simplex method is the basic variable that has the lowest value. has the largest coefficient in the key row. goes to zero first, as the entering basic variable is increased. has the smallest coefficient in the key row. d The leaving basic variable in simplex method is the basic variable that has the smallest coefficient in the key row. Comments Active
121 Value engineering is necessary to be used when the following symptoms are indicated
1. New product designs are to be introduced.
2. The firm is unable to meet delivery date.
3. Rate of return on investment goes down. Which of the above statement/s is/are correct?		 1, 2 & 3 2 only 1 & 3 only 2 & 3 only a Usually, when a product is expected to be statistically or practically absolute within a specific duration of time, the manufacture uses value engineering to save on costs without taking away the intended purpose. Comments Active
122 In the EOQ model, if the unit ordering cost gets doubled, then the EOQ will be reduced to half doubled increased 1.414 times decreased 1.414 times c \(\) \(EOQ Q^{*}=\frac{2DS}{H}\)
\(D=Annual demand\)
\(S=Order cost\)
\(H=Holding cost\)
\(Q^{*}∝S\)
As S. becomes double
\(Q^{*}∝25⇒Q^{*}∝2.5\)
\(Q^{*}∝1.4145\)		 Comments Active
123 The following is the general policy for A class items in ABC analysis:
1. Very strict control
2. Frequent review of their consumption
3. Safety stock kept
Which of these statement/s is/are correct?		 1 only 1 and 2 only 2 only 1, 2 and 3 d Category A: Products which are important and thus require tight control. Category B: Products which are of lower importance, but even so, must be managed with a medium level of control.
Category C: Products which are of lower importance and which only require the simplest level of control.		 Comments Active
124 Assertion (A): Vogel’s approximation method yields the best initial basic feasible solution of a transportation problem.
Reason (R): Vogel’s method give allocations to the lowest cost elements of the whole matrix.
Code:		 Both (A) and (R) are true. (R) is the correct explanation of (A). Both (A) and (R) are true. (R) is not the correct explanation of (A). (A) is true, but (R) is false. (A) is false, but (R) is true. b It is used to find out first feasible solution to a transportation problem by allocating the resources to the lowest cost cell. Comments Active
125 Assertion (A): Value analysis is superior to other conventional cost reduction techniques.
Reason (R): In conventional cost reduction techniques, value is increased by widening tolerance bands.
Code:		 Both (A) and (R) are true. (R) is the correct explanation of (A). Both (A) and (R) are true. (R) is not the correct explanation of (A). (A) is true, but (R) is false. (A) is false, but (R) is true. a Value analysis not only reduce the total cost but also uses very less no of resources and wide tolerance bend to do so sometimes it gives exact solution for a given set of problem. Comments Active
126 Value Engineering is concerned with the saving of Un-necessary costs Administrative difficulties Overhead costs Time a Overhead costs, often referred to as overhead or operating expenses, refer to those expenses associated with running a business that can’t be linked to creating or producing a product or service. They are the expenses the business incurs to stay in business, regardless of its success level.
* Rent
* Utilizes
* Insurance
* Salaries that aren’t job or product specific.
* Office equipment’s such as computers or telephones.
* Office supplies
Note Q. Nos. 76-77: Choose the correct relationship between the given statements of Assertion (A) and Reason (R) :		 Comments Active
127 Which of the following are said to be the benefits of assembly line balancing?
1. It minimize the in-process inventory.
2. It reduces the work content.
3. It smoothens the production flow.
4. It maintains the required rate of output. Select the correct answer using the codes given below :
Code:		 1, 2 and 3 2, 3 and 4 1, 3 and 4 1, 2 and 4 b Benefits of assembly line balancing in organization.
* Improved process efficiency
* Increased production rate
* Reduced total processing time
* Minimum or zero ideal time
* Potential increase in profits and decrease in costs
* Minimizing the number of workstations for a given cycles.
* Minimizing the cycle time for a given number of workstation.
* Minimizing the balance delay (or) maximizing the balancing efficiency.		 Comments Active
128 The following is not true for linear programming problems: Objective function is expressed as a linear function of variables. Resources are not limited. Some alternative course of actions are also available. Decision variables are inter related. b It always have limited resources. It is a set of linear function and not only method to find out the course of action. It is a structure with connected decision variable. Comments Active
129 Which one of the followings statements is not correct regarding simplex method of linear programming? It is an iterative procedure. It has a trial basic feasible solution to constraints. The collection of feasible solution does not constitute a convex set. It improves the first trial solution by a set of rules. c The collection of feasible solution constitutes a convex set. Comments Active
130 Which of the following is not the characteristics of work sampling? Any interruption during study will not affect the results. The study causes less fatigue. Uneconomical for short cycle jobs. A stop watch is needed. d Work sampling is a statistically based technique utilized for analyzing work performance and machine utilization by direct observation, but without a stop watch, So work sampling is another useful technique of work study. Comments Active
131 Which one of the following is most important parameter for EDM? Thermal capacity Hardness Strength Geometry a Characteristics of EDM
1. The process can be used to machine any work material if it is electrically conductive.
2. Material removal depends on mainly thermal properties of the work material rather than its strength, hardness etc.
3. In EDM there is a physical tool and geometry of the tool is the positive impression of the hole or geometric feature machined.
4. The tool has to be electrically conductive as well. The tool wear once again depends on the thermal properties of the tool material.
5. Though the local temperature rise is rather high, still due to very small pulse on time, there is not enough time for, the heat to diffuse and thus almost no increase in bulk temperature takes place.		 Comments Active
132 Choose the Correct relationship between the given statements of Assertion (A) and Reason (R).
Assertion (A): In case of control charts for variables, if some points fall outside the control limits, it is concluded that process is not under control.
Reason (R): It was experimentally proved by Shewart that averages of four or more consecutive readings from a universe (population) or from a process, when plotted, will form a normal distribution curve.
Code:		 Both (A) and (R) are correct. (R) is the correct explanation of (A). Both (a) and (R) are correct. (R) is not the correct explanation of (A). (A) is correct, but (R) is in correct. (A) is incorrect, but (R) is correct. b Control limit defines the stability of the process. These limits are calculated by control charts like , R, P, C charts etc Shewort did find out the population size and the plot of these size will always follow normal distribution. \(X\) Comments Active
133 TMU means Time Motion Unit Time Method Unit Time Measurement Unit Time Movement Unit c TMU stands for time measuring unit. In methods time measurement (MTM) system, a predetermined time is given to each motion. In motion study the time for each basic element is given in units of TMU
1 TMU = 0.000010 hr = 0.00060 min = 0.036 sec		 Comments Active
134 A comparator for its working depends on comparison with standard such as slip gauges accurately caliberated scale optical device limit gauge a In metrology, the comparator is an indirect type of precision measurement because it will not measure the dimension, it will indicate the difference in measurement between the given components with the actual working standard. The comparator is an indirect type of precision measurement because it will not measure the dimension, it will indicate the difference in measurement between the given component and working standard (usually slip gauge) and another magnification instrument is needed to measure this difference with accuracy. Comments Active
135 A hole of 1 mm is to be drilled in glass. It could be best done by Laser drilling Plasma drilling Ultrasonic drilling Electron beam drilling c For fragile material USM is most suitable machining. But other can also be used like LBM, EBM, PAM etc. Comments Active
136 In EDM process, the workpiece is connected to Cathode Anode Earth None of the above b In EDM, the workpiece is connected to the positive terminal, and the tool is connected to the negative terminal. Comments Active
137 A good machinability rating would indicate long tool life, high power requirement and less machining time. long tool life, low power requirement and a good surface finish. short tool life and a good surface finish. long tool life, high power requirement and a good surface finish. b The machinability rating of a material is the ease with which it can be cut by a tool to achieve the required finish. A material that is easy to machine required less power requirement, takes less time to cut, and will not wear, i.e. longer tool life, quickly. The outcome of this is a good surface finish. Comments Active
138 Electro-discharge machining uses the following dielectric fluid: Kerosene Sodium hydroxide Water Aqueous salt solution a An appropriate dielectric fluid (such as NaCl and NaNO3) is applied in ECM to assist flow of ions between two electrodes. Comments Active
139 The following is not true for ECM: It can machine highly complicated shapes in a single pass. Tool life is very high. Machinability of the work material is independent of its physical and mechanical properties. Kerosene is use as electrolyte. d Most commonly electrolyte used for ECM is a concentrated salt electrolyte, namely, sodium chloride or sodium nitrate.
Advantages
* It can machine very complicated surface.
* A single tool can be used to machining large number of work piece theoretically no tool wear occur.
* Machining of metal is independent on strength and hardness of tool.
* ECM gives very high surface finish.
Disadvantages
* High initial cost of machine.
* Design and tooling system is complex.
* Fatigue property of machined surface may reduce.
* Non – conductive material cannot be machined.
* Blind hole cannot be machined form ECM.
* Space and floor area requirement is high compare to conventional machining.		 Comments Active
140 The following is not the characteristics of explosive forming: Low capital cost of the set up. Very large components can be formed. Only a simple die is required. The tooling material is very expensive. d No special tooling required as it based on energy given by explosives. Comments Active
141 Choose the false statement from the following: Control chart indicate whether the process is in control or not. X and R charts are used to evaluate dispersion of measurements. P-chart is a control chart for percentage defective. C-charts are prepared for large and complex components. d The control chart is a graph used to study now a process changes over time. Data are plotted in time order.
The x – bar chart shows how the mean or average changes over time and R- chart shows how the range of the subgroups changes over time.
A P – chart is used to record the proportion of defective units in a sample
A C – chart is used to record the number of defects in a sample.
Shape of components does not affect these chart.		 Comments Active
142 Which is the false statement about electro discharge machining? It can machine very hard material. Very good surface finish is obtained. Section to be machined should be thick. Metal removal rate is very slow. c Advantages of EDM
* Any complicated shape that can be machine(d)
* It can also be employed for the extremely hardened work piece.
* No burns
* Good surface finish can be attained
* Creating small holes is not easily achieved by any other process other than EDM.
* Fragile and slender workplaces can be machined without distortion.
* The heat treatment process can be eliminated.
* Hard and corrosion resistant surfaces, essential needed for die making, can be developed by this process.
Disadvantage of EDM
* It can be applied to electrically conducting metals only
* Excessive tool wear
* High specific power consumption
* Profile machining of complex contours is not possible.
* The metal removal rate is slow
* Reproduction of sharp corners is the limitation of the process		 Comments Active
143 Which of the following are the quality control limits for p-charts? \(p±3p(1-p)\) \(p±3p(1-p)\) \(p±3\frac{p(1-p)}{n}\) \(p±3np(1-p)\) c The P formula (for the proportion of non – conforming units from sub – groups that can vary in size)
\(n=no of defectives\)
\(np=No of defectives\)
\(P=fraction defective\)
\(P=\frac{nP}{n}\)
\(P=\frac{Σnp}{Σn}\)
To calculated control limits for the p – chart
\(UCL_{P}, LCL_{P}=P±3\frac{P(1-P)}{n}\)		 Comments Active
144 Which of the following operation does not use a jig? Tapping Reaming Drilling Turning d A device that does both functions (holding the work and guiding a tool) is called a jig. The jigs are special tools particularly in drilling, reaming tapping and boring operation. Fixtures are used to holding the workpiece and used particularly in milling machine shapers and slotting machine. Comments Active
145 In an orthogonal cutting experiment, with a tool of rake angle γ=75° and shear angle φ = 22.8°, then friction angle β will be 41.9° 51.4° 61.2° None of the above d From merchant analysis of orthogonal cutting
\(2∅+β-α=π/2\)
Where ∅ = shear angle = 22.8°
𝛃 = Friction angle = ?
𝛂 = cutting rake angle = 75°
\(β=90+75-(2×22.8)=119.4°\)		 Comments Active
146 Which of the following values of index n is associated with carbide tools when Taylor’s tool life equation VTn = constant is applied? 0.65 to 0.90 0.45 to 0.60 0.20 to 0.40 0.10 to 0.15 c Taylor’s tool life equation
\(VT^{n}=C\)
Where
\(V=Cutting speed in m/min\)
\(T=tool life in min\)
\(n=an index related to cutting tool material\)
For high speed steel tools
\(n=0.1 to 0.5\)
For tungsten carbide tools,
\(n=0.2 to 0.4\)
For ceramic tools, \(n=0.4 to 0.6\)
a constant. It is numerically equal to the cutting speed that gives tool life of one minute \(C=\) \((C-V^{*}1^{n}=V)\)		 Comments Active
147 Which of the following materials require the largest shrinkage allowance while making a pattern for casting? Aluminium Brass Cast Iron Duralumin a In this question cast iron category is not mentioned so AI is correct ans.
Sr. no
Metal
Contraction (mm/m)
1
Grey cast iron
7 to 10.5
2
White cast iron
21
3
Malleable iron
15
4
Steel
20
5
Brass
14
6
Aluminium
18
7
Aluminium alloy
13 to 16
8
Bronze
10.5 to 21		 Comments Active
148 For TIG welding, which of the following gases are used ? Hydrogen and Carbon-di-oxide Argon and Helium Argon and Neon Hydrogen and Oxygen b Inert gas (TIG) or gas tungsten arc (GTA) welding is the arc welding process in which an arc is generated b/w a non – consumable tungsten electrode and workpiece. The tungsten electrode and the weld pool are shielded by an inert gas normally argon and helium. Comments Active
149 Profile of a gear tooth can be checked by Optical projector Optical pyrometer Bench micrometer Sine bar. a There are mainly four methods for gear profile check.
1. An optical comparator and profile projector are used to magnify the profile of the gear under test and then it is compared with the master profile.
2. An instrument designed to measure the contours of involute gear teeth in a section perpendicular to the axis of the gear wheel.
3. Large gear tooth is measured by tooth displacement method when there is no other option is available.
4. In computer controlled probe method scanning a force is applied at constant rate from root to tooth tip.		 Comments Active
150 Continuous chips will be formed when machining speed is low medium high independent of speed c Favorable condition for continuous chips.
- High cutting velocity
- Low feed and depth of cut
- Low rake angle
- Ductile material		 Comments Active
151 In USM, the tool is vibrated with the frequency of 5 kHz 10 kHz 15 kHz 20 kHz d In ultrasonic machining a tool of desired shape vibrates at an ultrasonic frequency (19~ 25 KHz) with an amplitude of around 15 – 50 μm over the workpiece. Comments Active
152 The process in which the material removal rate is governed by Faraday’s law is ? ECM EDM AJM LBM a ECM is a process of metal removed by controlled dissolution of anode of an electrolytic cell. The tool is cathode and work it anode the tool advances towards the anode through the electrolyte and metal is removed from the work – piece. The metal removal is governed by faraday’s low.
Faraday’s law states that the mass of the metal altered by the electrode is proportional to the quantity of electrical charges transferred to that electrode.		 Comments Active
153 In Electro-Discharge-Machining
(EDM), the tool is made of		 High Speed Steel Copper Cast Iron Glass b In EDM, electro conductive material i.e. Cu and graphite are commonly used as tool materials. The poor wear resistance is the drawback of these tools. EDM is used to machine materials such as carbides, heat resistance and super alloys which are difficult to machine materials. Comments Active
154 Explosive forming is not used for the following: Making very small complex parts. For large parts typical of aerospace industry. Both (a) & (b) above are correct. None of the above is correct. a Explosive farming is a process in which forces produced by an explosion are used to shape a workpiece. The explosive energy replaces the male part of the tool that is used in regular forming processes.
Applications:
- In aerospace and aircraft industry to produce large parts for which conventional tooling costs are high. It involves the discharge of explosives located at a predetermined distance from the workpiece, and water is generally used as the energy transfer medium.		 Comments Active
155 The relationship between the shear angle (φ), friction angle (β), cutting rake angle (α) and the machining constant (C). for the work material is 2α + β – φ = C 2α + β + φ = C 2φ + β – α = C 2φ + β + α = C a The relationship between the shear angle (, friction angle (), cutting rake angle (α) and the machining constant (c) for the work material is given by \(∅)\) \(β\)
Merchant theory
(For minimum energy consumption) \(2∅+β-α=Cm\)
In absence of any machining constant Cm the angle relationship is given by.
Ernest and Merchant Theory
= 40° \(2∅+β-α=π/4\)
Here
\(∅=Shear angle\)
\(β=friciton angle\)
\(α=rake angle (in degree)\)		 Comments Active
156 The Plug gauge is used to Check the size and shape of holes Measure the diameter of holes Measure the diameter of shafts Measure the diameters of shafts & holes a Go and NOGO are plug gauge is used to inspect the hole no to measure the diameter of hole. Comments Active
157 Life of a single point cutting tool is influenced by which of the following factors? Cutting speed Feed rate Depth of cut All the above d Tool life inversely depends on cutting velocity, feed and depth of cut. Comments Active
158 Which of the following instruments is used to measure smoothness of a metallic surface? Talysurf Coordinate Measuring Machine Profile Projector None of the above a Talysurf is used to measure the surface roughness by using an electronic principle, this surface meter consist of stylus and skit type instrument used for measuring the surface of the given product.
A co – ordinate measuring machine is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a probe.
Profile projector also known as a shadow graph, and it is useful item in a small parts machine shop or production line for a quality control inspection team.		 Comments Active
159 Which of the following should be more to reduce wear of a tool? Weight Density Hardness (b) & (c) both d Density and hardness of cutting tool \( Tool life ∝\) Comments Active
160 A cutting tool is turning a work piece of 40 mm diameter, revolving at 300 rpm. If tool life is 120 min, find the value of constant C as per the Taylor’s tool life equation, Assuming n = 1/7. 85 80 70 75 d \( V_{c}=πDN=π×40×300\)
\(=12000Ï€ mm/min\)
\(T=120 min\)
\(VT^{n}=C\)
\(12000Ï€(120)^{1/7}=C\)
\(C=74706.26=75 MPa\)		 Comments Active
161 The upper and lower control limits in case of R-chart are given by \(A_{2}R & A_{3}R\) \(D_{3}R & D_{4}R\) \(R±d_{3}R\) \(R±A_{2}R\) c The lower and upper control limits for the range chart are calculated using the formula.
\(LCL=R-md_{3}σ\)
\(UCL=R+md_{3}σ\)
Where m is a multiplier (usually set to 3) chosen to control the likelihood of false alarms, and d3 is a constant (which depends on n) that is calculated by numerical integration and is based on the assumption of normality. The relation for d3 is
\(d_{3}=\frac{σR}{σ}\)		 Comments Active
162 Which of the following is not true in case of jigs and fixtures? Consistency in dimension Fast production speed is not possible Auto-location control None of the above b Jigs: Used to locate work – piece and to guide the tool.
Fixture: Used to hold workpiece
These provide
- Accuracy
- Fast production
- Interchangeability
- Repeatability etc.		 Comments Active
163 In EDM, metal removal rate is proportional to Frequency of charging Energy delivered in each spark Both (a) and (b) None of the above c MRR ∝ Frequency & Energy Comments Active
164 The rake angle of a cutting tool is 15°, the shear angle is 45° and the cutting velocity is 35 mpm. What is the velocity of chip along the tool face? 28.5 mpm 27.3 mpm 25.3 mpm 23.5 mpm c \( α=15°\)
\(∅=45°\)
V = 35 m/min = Cutting velocity
\(\frac{V}{Cos(∅-α)}=\frac{V_{c}}{sin∅}=\frac{V_{s}}{cos α}\)
\(V_{c}=\frac{V.sin ∅}{Cos (∅-α)}=\frac{35 sin 45}{cos (45-10)}\)
= Chip flow velocity \(V_{c}=25.58 m/min\)		 Comments Active
165 An orthogonal cutting operation is being carried out under the following conditions: Cutting Speed = 2 m/sec, Depth of cut = 0.5 mm, Chip thickness = 0.6 mm. What is the chip velocity? 2 m/sec 2.4 m/sec 1 m/sec 1.66 m/sec d \(\) \(t=0.5 mm\)
\(t_{c}=0.6 mm\)
\(V=2 m/sec\)
\(V_{c}=?\)
\(\frac{V_{c}}{V}=\frac{t}{t_{c}}⇒V_{c}=\frac{V×t}{t_{c}}\)
\(V_{c}=1.66 m/sec\)		 Comments Active
166 Choose the alternative, which explains the correct relationship between the given statements, (a) & (R) from the code given below:
Assertion a: In ECM, the shape of the cavity is the mirror image of the tool, but unlike EDM, the tool wear in ECM is a cathode.
Reason (R): The tool in ECM is a cathode.
Code:		 Both (A) & (R) are true. (R) is the correct explanation of a Both (A) & (R) are true. (R) is not the correct explanation of (A). (A) is false, but (R) is true. (A) is true, but (R) is false. c In ECM, the shape of the cavity will be the mirror image of the tool, but unlike EDM, the tool wear in ECM is zero due to no contact between tool and workpiece. Tool in ECM will be connected to negative terminal. Comments Active
167 Which of the following are the reasons for reduction of tool life in a machining operation?
1. Temperature rise of cutting edge.
2. Chipping of tool edge due to mechanical impact.
3. Gradual wear at tool point.
4. Increase in feed of cut at constant cutting force
Select the answer from the following:		 1, 2 & 4 1, 2 & 3 1, 3 & 4 1, 2, 3 & 4 d Reduction of tool life is due to temperature, chipping of tool, wear and high fee(d) Comments Active
168 Binding material in cemented carbide tool is Graphite Lead Carbon Cobalt d Cobalt is widely used binder metal in cemented carbides, due to its good welting behavior, favorable mutual solubility with tungsten carbide and good mechanical properties. Comments Active
169 An example of amorphous material is Zinc Lead Glass Sulphur c Amorphous material means lack of ordered crystal structure and repeatability of a crystal structure. Amorphous film material can be formed by: deposition of a natural “glassy” material such as a glass composition. Deposition at low temperatures where the all atoms do not have enough mobility to form a crystalline structure (quenching) Comments Active
170 Pure iron is the structure of Ferrite Pearlite Austenite Cementite a iron is considered one of the most pure iron which have BCC structure. \( α- \) Comments Active
171 The ultimate tensile strength of low Carbon Steel by working at high strain rate will increase decrease remains constant first increase, then decrease a The ultimate tensile strength of low carbon steel by working at a high strain rate will increase.
For low carbon steels strain rate sensitivity
* After the ultimate strength has been exceeded, there is still considerably ductility in low carbon steel sheets.
* This is related to the strain rate sensitivity of the flow stress.
* Strain rate hardening may occur as well, due to its having a higher strain rate.
* Strain rate sensitivity (SRS) of flow stress is an important parameter for deformation mechanism of materials. Definition of SRS is based on incremental changes in strain rate during tests performed at a fixed microstructure, to determine corresponding changes in flow stress strain rate sensitive means a materials stress versus strain characteristics are dependent on the rate of loading.		 Comments Active
172 Babbitt materials are used for Gears Bearings Bolts Clutch liners b Babbitt is a lining for bearing cast iron, steel, and bronze shells. Comments Active
173 Which one of the following is the ferrous material? Zinc Iron Silicon Carbide Copper b Ferrous material are those which have iron constituent. Comments Active
174 The material commonly used for making machine tool bed is Mild Steel Aluminum Brass Cast Iron d Cast iron is used due to higher compressive strength and damping capacity. Comments Active
175 The property of material, which enables it to withstand bending without fracture, is known as Mechanical strength Stiffness Flexural rigidity Ductility c Flecxural Rigidity is defined as the force couple required to bend a fixed non – rigid structure by one unit of curvature or as the resistance offered by a structure while undergoing bending without rupture. As we increase the value of flexural rigidity the strength of the beam to resist bending also increases. The flexural rigidity of components can be increase by raising the moment of inertia of cross – section or by choosing the material with a higher modulus of elasticity.
Flexural rigidity: R = EI		 Comments Active
176 Which ingredient is responsible for corrosion resistant capability in Stainless Steel? Iron Chromium Zinc Sulphur b Chromium – Improves corrosion resistance
Zinc – Galvanised iron
Sulphur – Improves machinability		 Comments Active
177 Gradual time dependent deformation under constant load or self-weight is called Erosion Decay Tension Creep d Creep – Time dependent deformation Comments Active
178 The macro-structure of a material is generally examined by X-ray techniques Spectroscopic techniques Optical microscope Metallurgical microscope d Macro structures are examined by in general through naked eye, but here as per given option metallurgical telescope should select. Comments Active
179 Select the proper sequence for the following:
1. Proportional limit 2. Elastic limit
3. Yield point 4. Fracture/failure point		 1 – 2 – 3 – 4 2 – 1 – 3 – 4 1 – 2 – 4 – 3 2 – 1 – 4 – 3 a elastic limit, proportional limit, yielding, failure. Comments Active
180 The crystal structure of α-iron is Simple cubic Face centered cubic Body centered cubic Close-packed Hexagonal c \(\) \(α-Iron :BCC\)
\(γ-Iron :FCC\)
\(δ-Iron :BCC\)		 Comments Active
181 Match the items in List – 1 to the corresponding items in the List-2.
List -1
List – 2
(Heat Treatment)
(Effect on Properties)		 3 1 4 2 3 1 2 4 1 3 4 2 1 3 2 4 c Annealing will restore ductility following cold working and hence allow additional processing without cracking. Annealing may also be used to release mechanical stresses induced by grinding, machining et(c) Hence preventing distortion during subsequent higher temperature heat treatment operations. In some cases, annealing is used to improve electrical properties. For steels, subcritical annealing takes place at 550℃ - 650℃ so there is no crystal structure change. Intermediate annealing is carried out at 650 os there is some transformation to austenite and full annealing involves completely austenizing the work at 820℃ - 950℃. \(℃-750℃, \)
Normalization is mainly used on carbon and low alloyed steels to normalize the structure after forging, not rolling or casting normalizing depends on the steel dimension analysis and the cooling speed used [approximately 100 – 250 BHP] During normalizing. The material is heated to a temperature approximately equivalent to the hardening temperature.
Nitriding is a heat treatment process that diffuses nitrogen into the surface of a metal to create a case – hardened surface.
Mar tempering is also known as stepped quenching or interrupted quenching. In this process, steel is heated above the upper critical point (above the transformation range) and then quenched in a salt, oil, or lead both kept at a temperature of 150 - 300℃. The W/P is held at this temperature above martensite start point until the temperature becomes uniform throughout the cross – section of workpiece. After that it is cooled in air or oil to room temperature. In this process, Austenite is transformed to the martensite by step, quenching, at a rate fast enough to avoid the transformation of ferrite, pearlite or bainite.		 Comments Active
182 Dislocation in material is called Point defect Line defect Plane defect Volumetric defect b Line defects, or dislocations, are lines along which whole rows of atoms in a solid are arranged anomalously. The resulting irregularity in spacing is most severe along a line called the line of dislocation line defects can weaken or strengthen solids.
These are 3 types		 Comments Active
183 Select the correct answer out of the following alternatives about ‘Cyclic Stresses’. That a material can tolerate are much greater than stresses produced under static loading. Can lead to fatigue if the stress level is above the endurance limit. Can lead to fatigue if the stress level is below the endurance limit. Are not introduced in the axle of a running train b Cyclic stress is the distribution of forces that change over times in a repetitive fashion.
* Cyclic stresses given rise to fatigue processes that shorten component life – time, while corrosion tends to accelerate normal fatigue giving rice tot corrosion fatigue. It is the repetitive occurrence and redistribution of forces acting on a material. Periodic or regular cyclic stress conditions lead to increased wear and tear of the material, thus increasing the rate of material degradation and failure.
Endurance limit: It is defined as the stress below which a material can endure an infinite number of repeated load cycles without exhibiting failure.		 Comments Active
184 Dielectric strength can be reduced by removing cracks absence of imperfections absence of flaws impurities, cracks and pores d Dielectric strength refers to the ability of an insulating material to resist the utmost voltage imposed on it for a long duration without failure, the voltage at which failure occurs is known as breakdown voltage. Dielectric strength relies on many factors such as crystalline structure, imperfections and impurities found in the insulator material/number of electrons, and external factors such as the shape of the electrodes used to shed the electrical voltage/nature of the external surface and the test conditions which include temperature and humidity/source frequency and time period of applying voltage on the insulator and number of cycles and thickness of the sample. Comments Active
185 Choose the correct statement from the following: Ceramic compounds involve simple coordination than their corresponding components. Ceramic compounds are more ductile. Ceramic compounds are more stable with respect to thermal and chemical environments than their components. Ceramic compounds have less resistance to slip. c Ceramic structure are electrically neutral, more complex than metallic structures (Am Xp – type – AmBnXp – type) and are made up of two or more different elements. These are brittle in nature and insulators. Highly stable at high temperature, slip phenomena does not occur in ceramics because of brittleness. Comments Active
186 Assertion (A): Soft magnets are the obvious choice for ac or high frequency applications.
Reason (R): They must be magnetized and demagnetized many times per second).
Code:		 Both (A) and (R) are true, but (R) does not explain (a) correctly. Both (A) and (R) are true, and (R) explains (a) correctly. (A) is true, but (R) is false. (A) is false, but (R) is true. b Comments Active
187 Assertion (A): In general, materials deform more readily at elevated temperature.
Reason (R): Plastic deformation commonly arises from dislocation movements that involve a continual displacement of atoms to new neighbors at elevated temperature.
Code:		 (A) is true, but (R) is false. (A) is false, but (R) is true. Both (A) and (R) are true and (R) explains (A) correctly. Both (A) and (R) are true, but (R) does not explain (A) correctly. c Comments Active
188 Assertion (A): Little energy is required to break materials such as glass, polystyrene and some cast irons. Conversely, rubber and many steels absorb considerable energy in the fracture process.
Reason (R): The service limit in many engineering products is not the yield or ultimate strength, rather may be the energy associated with fracture propagation.
Code:		 Both (A) and (R) are true and (R) explains (a) correctly. Both (A) and (R) are true but (R) does not explain (A) correctly. (A) is true, but (R) is false. (A) is false, but (R) is true. a Comments Active
189 Choose the alternative from the code given below which explains the correct relationship between the Assertion (a) and Reason (R):
Assertion (A): Metallic Magnets cannot be used in high frequency circuits.
Reason (R): The low resistivity of metallic magnets permits heating from induced currents.
Code:		 (A) is true, but (R) is false. (A) is false, but (R) is true. Both (A) and (R) are true, but (R) does not explain (A) correctly Both (A) and (R) are true and (R) explains (A) correctly d Comments Active
190 Match the items in List– 1tothatoftheList–2andchoosethecorrectalternative.
List-1List-2		 1234 6234 4612 2161 c Al(8%) Ni (14%)Co(24%) + Cu(3%) + Fe(51%) Comments Active
191 The ductile-brittle transition temperature depends on size and shape of material, rate of loading, presence of notches, impurities and operating temperature depends on size but does not depend on shape of material does not depend on size of material does not depend on rate of loading but depends on presence of impurities a It is the transition temperature below which a ductile plastic specimen becomes brittle, i.e. when the ductile/brittle transition occurs – boundary between brittle and ductile behavior. This is usually not a specific temperature but rather a temperature spread over 10℃ range. It depends on stress – concentration & design features, Anisotropy, type of loading operating temperature, composition, shape and size of component etc. Comments Active
192 The processes, used to make the steel magnetically softer, are Annealing and Decarburization Decarburization and Quenching Annealing, Grain growth and Decarburization Grain growth and Quenching c These elements can all be reduced to levels well below their room temperature solubility in iron by annealing at 1300 to 1500℃ (2370 to 2730℉) in hydrogen for several hours. It is necessary to cool slowly from the high temperature to produce excellent soft magnetic properties. Comments Active
193 Bronze contains 70% Cu and 30% Zn 90% Cu and 10% Zn 75% Cu and 25% Zn None of the above d Bronze is a copper – based alloy that typically consists of approximately 88% copper and and 12% tin. Trace amounts of other metals, such as aluminium, manganese, phosphorous, and silicon, may also be present in the alloy. Comments Active
194 Mild Steel is an example of Substitution solid solution Interstitial solid solution Inter metallic compound None of the above b Interstitial solid solution. It forms when the solute atom is small enough to fit at interstitial site between the solvent atoms, example – mild steel.
Interstitial solid solution- Here solute atom is carbon and solvent item is iron.		 Comments Active
195 Griffith theory of failure is suitable for Mild Steel Low Carbon Steel Alloy Steel Glass d The Griffith theory states that a crack will propagate when the reduction in potential energy occurs, due to crack growth, is greater than or equal to the increase in surface energy due to the creation of new free surface. This theory is applicable to elastic materials that fracture in a brittle fashion.
Griffith Proposed that a brittle material contains a large number of fine cracks. He postulated a criterion for the propagation of such a crack in a brittle material During propagation, there is a release of what is called the elastic strain energy, some of the energy that is stored in the material as it is elastically deformed.
Griffin elliptical crack model.		 Comments Active
196 Babbit metal is an alloy of which one of the following? Lead and Tin Lead and Magnesium Tin and Bismuth None of the above a Tin basedSn = 88%
Sb = 8%
Cu = 4%
Lead based Pb = 85%
Sb = 10%
Cu = 5%		 Comments Active
197 Iron is Face Centered Cubic (FCC) at which one of the following temperatures? Room temperature 1400°C 910°C None of the above c ν – iron or Austenite occur at 910℃ to below 1400℃. FCC structure is found in ν – iron. Comments Active
198 German silver is an alloy of Silver and Tin Silver and Gold Nickel and Copper Nickel, Copper and Zinc d German silver – Cu – Zn – Ni alloy
Cu(50%) + Zn (19%) + Ni(30%)		 Comments Active
199 When mechanical properties of a material remain same in all directions at each point, such a material is called Isotropic Homogeneous Orthotropic+ Anisotropic a Isotropic Material: Same elastic property in all direction at each point.
Homogeneous Material: Same elastic property in all point at each direction.
Anisotropic Material: Different elastic property in all direction at each point.		 Comments Active
200 The [110] direction in a cubic unit cell is parallel to the following: Face diagonal of unit cell Edge of the cube Body diagonal of the cube None of the above a [110] = OB
\(1=x(OA)\)
\(1=y(AB)\)
\(0=z\)
OB = Face diagonal		 Comments Active