Full-Length Mock Test 3 — RRB JE CBT 2 Technical Abilities Pattern (100 MCQs)

Section A: Engineering Mechanics and Strength of Materials (20 Questions)

1. A force system in which all forces act along a single line is called:
   (a) Collinear (b) Concurrent (c) Coplanar non-concurrent (d) Non-coplanar
2. A force system in which all forces pass through a single point is called:
   (a) Concurrent (b) Collinear (c) Parallel (d) Non-coplanar non-concurrent
3. The moment of a force about a point is the product of the force and the:
   (a) Perpendicular distance from the point to the force's line of action (b) Force's magnitude squared (c) Time for which the force acts (d) Mass of the body on which it acts
4. Coulomb's law of friction states that the limiting friction force is proportional to the:
   (a) Normal reaction between the surfaces (b) Area of contact between the surfaces (c) Velocity of relative sliding (d) Temperature of the surfaces
5. The centroid of a triangle lies at the intersection of its:
   (a) Medians (b) Altitudes (c) Angle bisectors (d) Perpendicular bisectors of sides
6. The moment of inertia of a plane area about an axis is a measure of its resistance to:
   (a) Bending/rotation about that axis (b) Axial elongation only (c) Thermal expansion (d) Corrosion
7. Hooke's law states that stress is proportional to strain within the:
   (a) Elastic limit (b) Plastic region only (c) Region beyond the ultimate strength (d) Region of necking
8. The modulus of elasticity (Young's modulus) of a material is the ratio of:
   (a) Stress to strain within the elastic limit (b) Strain to stress within the elastic limit (c) Ultimate stress to yield stress (d) Shear stress to shear strain
9. The modulus of rigidity is the ratio of:
   (a) Shear stress to shear strain, within the elastic limit (b) Direct stress to direct strain (c) Volumetric stress to volumetric strain (d) Bending stress to shear strain
10. The bulk modulus of a material relates volumetric stress to:
    (a) Volumetric strain (b) Linear strain only (c) Shear strain only (d) Angular strain only
11. A cantilever beam is a beam that is:
    (a) Fixed at one end and free at the other (b) Simply supported at both ends (c) Fixed at both ends (d) Supported on more than two supports with no fixed end
12. A simply supported beam has supports that provide:
    (a) Vertical reaction only, with no moment resistance (b) Full fixity, resisting moment as well as force (c) No reaction of any kind (d) Only horizontal reaction, with no vertical support
13. The bending moment at a simple support of a simply supported beam (with no overhang or applied moment there) is:
    (a) Zero (b) Maximum (c) Equal to the total load (d) Undefined
14. The shear force diagram for a simply supported beam carrying a uniformly distributed load is:
    (a) A straight line, varying linearly along the span (b) A horizontal line, constant along the span (c) A parabolic curve (d) Zero throughout the span
15. The bending moment diagram for a simply supported beam carrying a uniformly distributed load is:
    (a) A parabolic curve (b) A straight line (c) Zero throughout the span (d) A step function with sudden jumps
16. The section modulus of a beam's cross-section is defined as the:
    (a) Moment of inertia divided by the distance to the extreme fibre (b) Area of the cross-section only (c) Moment of inertia multiplied by the distance to the extreme fibre (d) Perimeter of the cross-section
17. A thin cylindrical pressure vessel under internal pressure develops a hoop (circumferential) stress that is, compared to the longitudinal stress:
    (a) Twice the longitudinal stress (b) Half the longitudinal stress (c) Exactly equal to the longitudinal stress (d) Unrelated to the longitudinal stress
18. Euler's theory of column buckling predicts the critical (buckling) load for a:
    (a) Long, slender column (b) Short, stocky column, where crushing governs (c) Column under pure tension only (d) Beam under pure bending only, with no axial load
19. The slenderness ratio of a column is the ratio of its effective length to its:
    (a) Least radius of gyration (b) Cross-sectional area (c) Modulus of elasticity (d) Total mass
20. Torsion of a circular shaft produces a shear stress distribution that is:
    (a) Maximum at the outer surface and zero at the centre (b) Uniform throughout the cross-section (c) Maximum at the centre and zero at the outer surface (d) Zero everywhere in the cross-section

Section B: Thermodynamics, IC Engines, and Power Plant Engineering (20 Questions)

21. The zeroth law of thermodynamics underlies the concept of:
    (a) Temperature measurement (thermal equilibrium) (b) Energy conservation (c) Entropy increase (d) Absolute zero attainment
22. An isothermal process occurs at constant:
    (a) Temperature (b) Volume (c) Pressure (d) Entropy
23. An adiabatic process is one in which there is:
    (a) No heat transfer to or from the system (b) No work done by or on the system (c) Constant temperature throughout (d) Constant pressure throughout
24. An isochoric (isometric) process occurs at constant:
    (a) Volume (b) Temperature (c) Pressure (d) Entropy
25. An isobaric process occurs at constant:
    (a) Pressure (b) Volume (c) Temperature (d) Entropy
26. Entropy is a measure of a system's:
    (a) Degree of disorder/randomness (b) Total mechanical energy only (c) Total kinetic energy only (d) Electrical conductivity
27. According to the Second Law of Thermodynamics, the entropy of an isolated system tends to:
    (a) Increase or remain constant, never decrease (b) Always decrease over time (c) Remain exactly zero at all times (d) Become negative under certain conditions
28. The thermal efficiency of a heat engine is defined as the ratio of:
    (a) Net work output to heat input (b) Heat input to net work output (c) Heat rejected to heat input (d) Heat input to heat rejected
29. In a four-stroke petrol engine, the four strokes are, in order:
    (a) Suction, compression, power (expansion), exhaust (b) Compression, suction, exhaust, power (c) Power, exhaust, suction, compression, repeated in reverse (d) Exhaust, power, compression, suction
30. A two-stroke engine completes its cycle in:
    (a) One revolution of the crankshaft (two strokes) (b) Two revolutions of the crankshaft (four strokes) (c) Four revolutions of the crankshaft (d) Half a revolution of the crankshaft
31. The compression ratio of an IC engine is the ratio of:
    (a) Total cylinder volume to clearance volume (b) Clearance volume to total cylinder volume (c) Swept volume to clearance volume exactly, with no total volume term (d) Bore diameter to stroke length
32. Volumetric efficiency of an IC engine is a measure of how effectively the engine:
    (a) Fills its cylinder with fresh charge compared to the theoretical maximum (b) Converts fuel energy into work with no loss (c) Removes exhaust gases at zero flow resistance (d) Converts electrical energy into mechanical energy
33. A carburettor in a petrol engine is used to:
    (a) Prepare and supply the air-fuel mixture to the engine (b) Ignite the air-fuel mixture (c) Compress the intake air only, with no fuel metering (d) Cool the engine's cylinder head
34. In a diesel engine, fuel is introduced into the cylinder by:
    (a) Direct injection into the highly compressed, heated air (b) Carburetion, mixed with air before compression (c) A spark plug igniting a pre-mixed charge (d) Manual pouring through an open valve
35. A boiler in a steam power plant is used to:
    (a) Convert water into steam by heat addition (b) Condense steam back into water (c) Compress air for combustion (d) Generate electricity directly with no steam involved
36. In a Rankine cycle, the condenser's function is to:
    (a) Condense the turbine's exhaust steam back into water (b) Generate steam from water (c) Expand steam to produce work (d) Compress water to boiler pressure
37. A cooling tower in a thermal power plant is used to:
    (a) Reject waste heat from the condenser cooling water to the atmosphere (b) Generate steam for the turbine (c) Compress air for combustion (d) Store fuel for the boiler
38. In a gas turbine (Brayton cycle) power plant, the main components are the compressor, combustor, and:
    (a) Turbine (b) Boiler (c) Condenser (d) Reciprocating piston
39. A supercharger (or turbocharger) in an IC engine is used to:
    (a) Increase the density of air supplied to the cylinder, boosting power output (b) Reduce the compression ratio to zero (c) Replace the need for a carburettor or injector entirely (d) Cool the exhaust gases before release
40. Nuclear power plants generate heat through the process of:
    (a) Nuclear fission of a fissile material such as uranium-235 (b) Direct combustion of nuclear fuel in air (c) Chemical reaction between nuclear fuel and oxygen (d) Solar radiation concentrated onto the reactor core

Section C: Theory of Machines and Machine Design (20 Questions)

41. A mechanism is a kinematic chain in which at least one link is:
    (a) Fixed, allowing relative motion of the other links (b) Free to move in any direction with no fixed reference at all (c) Rigidly connected to every other link with no relative motion possible (d) Made of a non-rigid material
42. The degree of freedom of a mechanism indicates the number of:
    (a) Independent parameters needed to completely specify its configuration (b) Links in the mechanism only (c) Joints in the mechanism only (d) Gears in the mechanism only
43. A four-bar chain mechanism, when the shortest link is fixed, produces:
    (a) A double-crank mechanism (b) No motion at all (c) A rigid, immovable structure (d) Motion only in one fixed direction with no continuous rotation possible
44. In a slider-crank mechanism, the reciprocating member is called the:
    (a) Slider (piston) (b) Crank (c) Connecting rod (d) Fixed frame
45. A cam-follower mechanism converts:
    (a) Rotary motion of the cam into a desired reciprocating/oscillating motion of the follower (b) Only reciprocating motion into reciprocating motion (c) Only linear motion into linear motion of equal magnitude (d) Electrical energy directly into mechanical energy with no motion conversion
46. A gear train consisting of gears mounted so their axes remain fixed relative to the frame is called a:
    (a) Simple (or compound) gear train (b) Epicyclic (planetary) gear train (c) A belt drive, not a gear train at all (d) A chain drive, not a gear train at all
47. An epicyclic (planetary) gear train is characterised by having:
    (a) At least one gear axis that itself moves relative to the frame (b) All gear axes fixed relative to the frame with no moving axis (c) No gears at all, only pulleys (d) Only a single gear with no meshing pair
48. The velocity ratio of a simple gear train (ignoring idler gears) depends on the:
    (a) Ratio of teeth on the driven gear to teeth on the driving gear (b) Number of idler gears only, regardless of tooth counts (c) Distance between gear centres only (d) Colour of the gears
49. A flywheel is used in a machine primarily to:
    (a) Store kinetic energy and smooth out speed fluctuations during the cycle (b) Increase the machine's overall weight for stability with no energy storage role (c) Generate electrical power directly (d) Reduce the machine's operating speed permanently to near zero
50. A governor, unlike a flywheel, is used to control:
    (a) The mean speed of the engine in response to changes in load, over many cycles (b) Cyclic speed fluctuations within a single cycle (c) Only the engine's fuel colour (d) Only the engine's exhaust temperature
51. Balancing of rotating masses is done to:
    (a) Eliminate or minimize the effects of unbalanced centrifugal forces (b) Increase vibration deliberately for testing purposes (c) Increase the machine's operating temperature (d) Reduce the machine's speed to zero
52. A universal (Hooke's) joint is used to transmit rotary motion between:
    (a) Two shafts whose axes intersect at an angle (b) Two perfectly coaxial shafts only, with no misalignment (c) Only shafts moving in pure translation, with no rotation (d) A shaft and a stationary frame with no motion transmitted
53. The velocity of a piston in a slider-crank mechanism is maximum at approximately:
    (a) The point where the crank angle is around 90° from top dead centre (approximate, exact value depends on connecting rod ratio) (b) Exactly at top dead centre (c) Exactly at bottom dead centre only, never elsewhere (d) Only when the crank is stationary
54. In gear terminology, the "pitch circle" is the:
    (a) Imaginary circle on which gear tooth calculations are based, corresponding to a smooth rolling contact (b) Circle passing through the tooth tips (addendum circle) (c) Circle passing through the tooth roots (dedendum circle) (d) Circle at the gear's outer casing only
55. A helical gear, compared to a spur gear, has teeth cut:
    (a) At an angle (helix angle) to the gear axis (b) Exactly parallel to the gear axis, identical to a spur gear (c) Perpendicular to the gear axis (d) In a purely radial direction with no axial component
56. A worm gear set provides:
    (a) A high speed reduction ratio in a compact form, with the worm typically self-locking (b) Only a 1:1 speed ratio, with no reduction possible (c) Speed increase only, never reduction (d) No torque transmission capability at all
57. The "static balancing" of a rotor requires that the:
    (a) Resultant of all centrifugal forces be zero (b) Rotor be perfectly rigid with no mass distribution considered (c) Rotor operate only at zero speed (d) Rotor's colour be uniform throughout
58. "Dynamic balancing" of a rotor, in addition to static balance, requires that the:
    (a) Resultant couple due to the unbalanced forces also be zero (b) Rotor's mass be reduced to zero (c) Rotor operate only in a vacuum (d) Rotor's temperature remain exactly constant
59. The design of a bolted joint under tensile load considers, among other factors, the bolt's:
    (a) Core (root) diameter and the material's allowable stress (b) Only the bolt's outer paint colour (c) Only the number of washers used, with no stress calculation (d) Only the wrench size required for installation
60. A welded joint's strength depends significantly on the:
    (a) Throat thickness and weld length (b) Colour of the weld bead only (c) Ambient humidity at the time of welding only, with no other factor (d) Distance from the nearest unrelated component

Section D: Fluid Mechanics, Manufacturing, Metrology, Heat Transfer, and Material Science (20 Questions)

61. Pascal's law states that pressure applied to an enclosed, incompressible fluid is transmitted:
    (a) Equally in all directions throughout the fluid (b) Only in the direction of the applied force, with no other direction affected (c) Only vertically downward, regardless of the applied direction (d) Only along the container's walls
62. Bernoulli's equation, for an ideal (incompressible, non-viscous) fluid in steady flow, expresses the conservation of:
    (a) Total mechanical energy (pressure, kinetic, and potential) along a streamline (b) Electrical energy only (c) Chemical energy only (d) Nuclear energy only
63. A Venturi meter is used to measure:
    (a) Flow rate, based on the pressure difference at a constriction (b) Only fluid temperature (c) Only fluid colour/turbidity (d) Only fluid viscosity directly
64. A centrifugal pump converts:
    (a) Mechanical (rotational) energy into hydraulic (pressure/kinetic) energy of the fluid (b) Hydraulic energy directly into electrical energy (c) Thermal energy into mechanical energy directly, with no fluid involved (d) Chemical energy into hydraulic energy directly
65. A Pelton wheel is an example of an:
    (a) Impulse turbine (b) Reaction turbine exclusively (c) Positive displacement pump (d) Centrifugal compressor
66. A Kaplan turbine is best suited for sites with:
    (a) Low head and high flow rate (b) Very high head and low flow rate only (c) No flow at all (d) Only extremely small-scale installations
67. Sand casting is a manufacturing process in which molten metal is poured into a mould made of:
    (a) Sand, bonded with a suitable binder (b) Solid steel with no cavity at all (c) Ice, melted immediately upon contact (d) Paper, dissolved immediately upon contact
68. Arc welding uses heat generated by:
    (a) An electric arc between an electrode and the workpiece (b) Friction between two solid surfaces only (c) A chemical reaction with no electrical input at all (d) Purely mechanical hammering with no heat source
69. In a lathe machine, the workpiece is typically held and rotated while the cutting tool:
    (a) Remains stationary in rotation but can move linearly to remove material (b) Rotates at the same speed as the workpiece, with no relative motion (c) Remains completely fixed with no motion of any kind (d) Rotates faster than the workpiece at all times, with no linear feed
70. A milling machine differs from a lathe primarily in that the milling cutter:
    (a) Rotates while the workpiece is typically held stationary or fed linearly (b) Never rotates under any condition (c) Is always identical in shape and function to a lathe tool (d) Cannot remove any material at all
71. A clearance fit between mating parts always results in the shaft being:
    (a) Smaller than the hole (b) Larger than the hole (c) Exactly identical in size to the hole (d) Unrelated in size to the hole
72. A micrometer screw gauge typically achieves a finer measurement precision than a vernier caliper, commonly reading to:
    (a) 0.01 mm (b) 1 mm (c) 10 mm (d) 100 mm
73. Conduction heat transfer through a solid is governed by:
    (a) Fourier's law (b) Newton's law of cooling (c) Stefan-Boltzmann law (d) Pascal's law
74. The coefficient of performance (COP) of a refrigeration system is the ratio of:
    (a) Refrigerating effect to work input (b) Work input to refrigerating effect (c) Condenser capacity to evaporator capacity (d) Compressor speed to refrigerant charge
75. Face-centred cubic (FCC) crystal structure in metals like aluminium generally gives good:
    (a) Ductility (b) Brittleness with no ductility (c) Magnetism exclusively (d) Radioactivity
76. Hardening of steel, followed by quenching, produces a hard but brittle microstructure requiring subsequent:
    (a) Tempering (b) Complete remelting (c) No further treatment of any kind (d) Immediate machining with no stress relief
77. Grey cast iron, compared to ductile (nodular) cast iron, generally has:
    (a) Lower tensile strength and ductility (b) Higher tensile strength and ductility (c) Identical properties in every respect (d) No carbon content at all
78. A shell-and-tube heat exchanger consists of a bundle of tubes enclosed within a:
    (a) Cylindrical shell (b) Flat rectangular plate stack only (c) Solid, non-hollow block with no fluid passage (d) Vacuum chamber with no shell at all
79. In a counter-flow heat exchanger arrangement, the two fluids flow:
    (a) In opposite directions (b) In the same direction (c) Only perpendicular to each other (d) Only intermittently, never continuously
80. A screw pitch gauge is used for a quick, approximate check of a screw thread's:
    (a) Pitch (b) Overall length only (c) Material hardness (d) Surface colour

Section E: General Awareness, Computer Applications, and Current Affairs (20 Questions)

81. The Bureau of Indian Standards (BIS) is primarily responsible for:
    (a) Standardisation and quality certification of goods (b) Railway safety inspections exclusively (c) Currency printing (d) Postal regulation
82. The full form of "CAD" in engineering design software is:
    (a) Computer-Aided Design (b) Central Assembly Diagram (c) Combined Automated Drafting (d) Controlled Analog Device
83. The full form of "CAM" as used alongside CAD in manufacturing is:
    (a) Computer-Aided Manufacturing (b) Central Automated Machinery (c) Combined Assembly Method (d) Controlled Analog Machining
84. RAM in a computer is:
    (a) Volatile memory, losing contents when power is removed (b) Non-volatile memory, retaining contents without power (c) Used only for permanent archival storage (d) Found only in printers
85. The full form of "URL" is:
    (a) Uniform Resource Locator (b) Universal Reference Link (c) Unified Router Location (d) Unique Resource Language
86. An operating system's primary function is to:
    (a) Manage hardware resources and provide a platform for applications (b) Only display a decorative screen background (c) Only manage internet browsing (d) Only manage printer connections
87. "Make in India" as a national initiative primarily aims to:
    (a) Boost domestic manufacturing and reduce import dependence (b) Increase imports exclusively (c) Discourage all domestic manufacturing (d) Apply only to the textile sector
88. The National Manufacturing Policy in India aims to increase manufacturing's share in:
    (a) The national GDP (b) Only agricultural output (c) Only the service sector's output (d) Only foreign direct investment inflows
89. Indian Railways' primary rolling stock manufacturing units include facilities such as:
    (a) Integral Coach Factory and Chittaranjan Locomotive Works (b) Only private-sector automobile plants (c) Only foreign-owned assembly plants (d) Only shipyards, with no rail manufacturing at all
90. The Skill India initiative primarily aims to:
    (a) Provide vocational training and skill development for employability (b) Reduce the total number of skilled workers in the country (c) Apply only to government employees (d) Eliminate the need for technical education entirely
91. 3D printing (additive manufacturing) builds parts by:
    (a) Adding material layer by layer based on a digital model (b) Removing material from a solid block, exactly like conventional machining (c) Casting molten metal into a mould exclusively (d) Forging metal under high pressure exclusively
92. Industry 4.0 refers to the integration of:
    (a) Digital technologies (IoT, automation, data analytics) into manufacturing (b) Only manual, non-automated production methods (c) Only 19th-century steam-powered manufacturing (d) Only agricultural production techniques
93. The "National Skill Development Mission" in India works to coordinate skill development efforts across:
    (a) Various ministries, states, and sectors (b) Only a single private company (c) Only one specific state, with no national scope (d) Only foreign countries, with no domestic focus
94. A "digital twin" in modern engineering asset management refers to:
    (a) A virtual, data-driven replica of a physical asset for monitoring/simulation (b) A physical duplicate built for no functional reason (c) A method of concrete curing (d) A method of soil testing
95. Renewable energy sources being promoted in India for reducing carbon emissions include:
    (a) Solar and wind energy (b) Only coal-based thermal power (c) Only nuclear power exclusively (d) Only imported fossil fuels
96. The Production Linked Incentive (PLI) scheme in India is designed to:
    (a) Boost domestic manufacturing in targeted sectors through financial incentives (b) Discourage all manufacturing investment (c) Apply only to the handicraft sector (d) Eliminate the need for any government support to industry
97. Automation and robotics in modern manufacturing are primarily aimed at improving:
    (a) Productivity, consistency, and safety in repetitive/hazardous tasks (b) Only the aesthetic appearance of the factory building (c) Only the colour scheme of finished products (d) Only the administrative paperwork of a factory
98. Lean manufacturing philosophy primarily focuses on:
    (a) Eliminating waste while maximising value to the customer (b) Maximising inventory levels at all times regardless of demand (c) Eliminating all quality control checks (d) Increasing production lead time deliberately
99. Total Productive Maintenance (TPM) aims to achieve:
    (a) Maximum equipment effectiveness through proactive and preventive maintenance involving all employees (b) Complete elimination of any maintenance activity (c) Maintenance performed only after complete equipment failure (d) Maintenance performed exclusively by external contractors with no employee involvement
100. The acronym "RRB" in the context of this examination stands for:
     (a) Railway Recruitment Board (b) Regional Rural Bank (c) Reserve Reconciliation Bureau (d) Road Regulatory Body

Answer Key with Explanations

1.(a) A collinear force system has all forces acting along a single line.

2.(a) A concurrent force system has all forces passing through one point.

3.(a) Moment = force × perpendicular distance to the line of action.

4.(a) Limiting friction is proportional to the normal reaction (Coulomb's law).

5.(a) A triangle's centroid is at the intersection of its medians.

6.(a) Moment of inertia measures resistance to bending/rotation about an axis.

7.(a) Hooke's law holds within the elastic limit.

8.(a) Young's modulus = stress/strain within the elastic limit.

9.(a) Modulus of rigidity = shear stress/shear strain within elastic limit.

10.(a) Bulk modulus relates volumetric stress to volumetric strain.

11.(a) A cantilever beam is fixed at one end, free at the other.

12.(a) Simple supports provide vertical reaction only, no moment resistance.

13.(a) Bending moment at a simple support is zero.

14.(a) SFD for a UDL-loaded simply supported beam is a straight line.

15.(a) BMD for a UDL-loaded simply supported beam is parabolic.

16.(a) Section modulus = moment of inertia / distance to extreme fibre.

17.(a) Hoop stress is twice the longitudinal stress in a thin cylinder.

18.(a) Euler's theory applies to long, slender columns.

19.(a) Slenderness ratio = effective length / least radius of gyration.

20.(a) Torsional shear stress is maximum at the outer surface, zero at the centre.

21.(a) The zeroth law underlies temperature measurement via thermal equilibrium.

22.(a) An isothermal process occurs at constant temperature.

23.(a) An adiabatic process has no heat transfer.

24.(a) An isochoric process occurs at constant volume.

25.(a) An isobaric process occurs at constant pressure.

26.(a) Entropy measures a system's degree of disorder.

27.(a) Isolated system entropy never decreases (Second Law).

28.(a) Thermal efficiency = net work output / heat input.

29.(a) Four-stroke order: suction, compression, power, exhaust.

30.(a) A two-stroke engine completes its cycle in one crankshaft revolution.

31.(a) Compression ratio = total cylinder volume / clearance volume.

32.(a) Volumetric efficiency measures actual vs. theoretical charge filling.

33.(a) A carburettor prepares and supplies the air-fuel mixture.

34.(a) In diesel engines, fuel is directly injected into compressed, heated air.

35.(a) A boiler converts water into steam via heat addition.

36.(a) The condenser condenses turbine exhaust steam back to water.

37.(a) A cooling tower rejects waste heat from condenser cooling water.

38.(a) Gas turbine components: compressor, combustor, and turbine.

39.(a) A supercharger/turbocharger increases intake air density, boosting power.

40.(a) Nuclear plants generate heat via nuclear fission.

41.(a) A mechanism has at least one fixed link, allowing relative motion.

42.(a) Degree of freedom = independent parameters needed to specify configuration.

43.(a) Fixing the shortest link of a four-bar chain gives a double-crank mechanism.

44.(a) In a slider-crank mechanism, the slider (piston) reciprocates.

45.(a) A cam-follower converts rotary cam motion into desired follower motion.

46.(a) A simple/compound gear train has all gear axes fixed relative to the frame.

47.(a) An epicyclic gear train has at least one moving gear axis.

48.(a) Simple gear train velocity ratio depends on driven/driving tooth count ratio.

49.(a) A flywheel stores kinetic energy, smoothing cyclic speed fluctuations.

50.(a) A governor controls mean speed in response to load changes over many cycles.

51.(a) Balancing eliminates/minimizes unbalanced centrifugal force effects.

52.(a) A universal joint transmits rotation between shafts whose axes intersect at an angle.

53.(a) Piston velocity is maximum near about 90° crank angle from TDC (approximately).

54.(a) The pitch circle is the imaginary circle basis for gear tooth calculations.

55.(a) Helical gear teeth are cut at an angle (helix angle) to the axis.

56.(a) A worm gear set gives high, compact speed reduction, often self-locking.

57.(a) Static balancing requires the resultant of centrifugal forces to be zero.

58.(a) Dynamic balancing additionally requires the resultant couple to be zero.

59.(a) Bolted joint design considers core diameter and allowable stress.

60.(a) Weld joint strength depends on throat thickness and weld length.

61.(a) Pascal's law: pressure is transmitted equally in all directions in an enclosed fluid.

62.(a) Bernoulli's equation expresses conservation of total mechanical energy along a streamline.

63.(a) A Venturi meter measures flow rate via pressure difference at a constriction.

64.(a) A centrifugal pump converts mechanical energy into hydraulic energy.

65.(a) A Pelton wheel is an impulse turbine.

66.(a) A Kaplan turbine suits low head, high flow rate sites.

67.(a) Sand casting uses a sand mould bonded with a binder.

68.(a) Arc welding uses heat from an electric arc.

69.(a) In a lathe, the tool doesn't rotate but moves linearly while the workpiece rotates.

70.(a) In milling, the cutter rotates while the workpiece is typically held/fed.

71.(a) A clearance fit has the shaft smaller than the hole.

72.(a) A micrometer typically reads to about 0.01 mm.

73.(a) Conduction is governed by Fourier's law.

74.(a) COP = refrigerating effect / work input.

75.(a) FCC structure gives good ductility.

76.(a) Hardened steel requires tempering to reduce brittleness.

77.(a) Grey cast iron has lower tensile strength/ductility than ductile iron.

78.(a) A shell-and-tube exchanger has tubes within a cylindrical shell.

79.(a) In counter-flow, fluids flow in opposite directions.

80.(a) A screw pitch gauge checks thread pitch.

81.(a) BIS handles standardisation and quality certification.

82.(a) CAD stands for Computer-Aided Design.

83.(a) CAM stands for Computer-Aided Manufacturing.

84.(a) RAM is volatile memory.

85.(a) URL stands for Uniform Resource Locator.

86.(a) An OS manages hardware resources and provides an application platform.

87.(a) "Make in India" boosts domestic manufacturing, reducing import dependence.

88.(a) The National Manufacturing Policy aims to raise manufacturing's GDP share.

89.(a) Indian Railways manufacturing units include ICF and CLW.

90.(a) Skill India provides vocational training for employability.

91.(a) 3D printing adds material layer by layer from a digital model.

92.(a) Industry 4.0 integrates digital technologies into manufacturing.

93.(a) The National Skill Development Mission coordinates efforts across ministries/states/sectors.

94.(a) A digital twin is a virtual, data-driven replica of a physical asset.

95.(a) India promotes solar and wind energy for emission reduction.

96.(a) The PLI scheme boosts manufacturing via financial incentives in targeted sectors.

97.(a) Automation/robotics improve productivity, consistency, and safety.

98.(a) Lean manufacturing eliminates waste while maximising customer value.

99.(a) TPM aims for maximum equipment effectiveness via proactive maintenance involving all employees.

100.(a) RRB stands for Railway Recruitment Board.