JSSC- JE Mechanical Engg. Question Bank 2

Mechanical

What is a coplanar force system?

• A system where all forces lie in the same plane
• A system where forces act only in one direction
• A system where forces do not intersect at a point
• A system where all forces lie in different planes

Explanation:

• A coplanar force system is one in which all the forces acting on a body lie in a single plane.

Three collinear horizontal forces of magnitudes 250 N, 150 N and 350 N are acting on a rigid body. If the 150 N force acts in the opposite direction, determine the resultant force.

• 350 N
• 250 N
• 450 N
• 550 N

Explanation:

• Taking the 250 N and 350 N forces in one direction and 150 N in the opposite direction, resultant = 250 + 350 − 150 = 450 N.

In the resolution of a force, along which of the following directions is a force generally resolved?

• Two mutually perpendicular directions
• Any three random directions
• A single fixed direction
• Two parallel directions

Explanation:

• A force is generally resolved into two mutually perpendicular components, usually horizontal and vertical components.

What is the purpose of introducing two equal and opposite forces at a different point on a rigid body?

• To transfer the original force to a new location
• To change the direction of the applied force
• To balance the rotational motion of the body
• To increase the force acting on the body

Explanation:

• An equal and opposite force pair can be introduced to transfer a force to another point while creating an equivalent force-couple system.

In the analytical method, how is the resultant force determined when all forces act in the same direction?

• By adding all the forces
• By subtracting the smallest force from the largest
• By dividing the total force by the number of forces
• By multiplying all the forces together

Explanation:

• When forces act in the same direction, their magnitudes are added algebraically to obtain the resultant.

Why is the concept of transmissibility of forces valid for a rigid body?

• Because a rigid body does not deform under applied forces
• Because forces always act in the direction of motion
• Because internal forces in a rigid body do not exist
• Because a rigid body always has an infinite number of forces acting on it

Explanation:

• For a rigid body, moving a force along its line of action does not change its external effect on the body.

According to the Principle of Resolution, the algebraic sum of the resolved parts of multiple forces in a given direction is equal to:

• The total magnitude of all forces combined
• The resolved part of their resultant in the same direction
• The sum of all forces acting in that direction
• The difference between the largest and smallest force

Explanation:

• The component of the resultant along any direction equals the algebraic sum of the components of all individual forces along that direction.

What does the Polygon Law of Forces describe?

• The equilibrium condition of multiple forces
• The force required to balance a single force
• The interaction between two perpendicular forces
• The method to find the resultant of multiple forces

Explanation:

• The polygon law determines the resultant of several forces by arranging their vectors head-to-tail.

If two forces act at a right angle (90°), what will be the magnitude of their resultant force?

• R = F₁ + F₂
• R = √(F₁² + F₂²)
• R = 2F₁F₂ cos θ
• R = F₁ − F₂

Explanation:

• For perpendicular forces, the resultant is obtained using Pythagoras’ theorem.

Fatigue failure in materials occurs due to:

• Constant stress
• High temperature
• Cyclic loading
• Low temperature

Explanation:

• Fatigue failure occurs when a material is subjected to repeated or fluctuating stresses over time.

Which test is commonly used to measure the malleability of a material?

• Torsion test
• Compression test
• Hardness test
• Impact test

Explanation:

• Malleability is the ability of a material to undergo plastic deformation under compressive loading without fracture.

What happens to the mechanical properties of mild steel when carbon content increases?

• Strength decreases and ductility increases
• Both strength and hardness decrease
• Strength increases and ductility decreases
• Both strength and ductility increase

Explanation:

• Increasing carbon content generally increases hardness and strength while reducing ductility and weldability.

The diagram shows stress-strain curves of two materials. Material A has a finer grain structure while Material B has a coarser grain structure. Which statement is correct regarding their toughness?

• Material A has lower toughness than Material B
• Both materials have the same toughness
• Material A has higher toughness than Material B
• Toughness can be determined directly by comparing the slopes of the stress-strain curves

Explanation:

• Toughness is represented by the area under the stress-strain curve up to fracture. The finer-grained material shown has the greater area.

Which of the following is true about the weldability of mild steel and alloy steel?

• Alloy steel is easier to weld than mild steel
• Weldability depends only on the thickness of the steel
• Mild steel is easier to weld than alloy steel
• Both mild and alloy steel have the same weldability

Explanation:

• Mild steel has relatively low carbon content and generally has better weldability than many alloy steels.

A material exhibits a large amount of plastic deformation before fracture and can absorb significant energy. This material is said to have:

• High hardness
• High strength
• High modulus of elasticity
• High toughness

Explanation:

• Toughness is the ability of a material to absorb energy before fracture, particularly through plastic deformation.

What is the typical behaviour of creep deformation in materials at very high temperatures above 0.5 times the melting temperature?

• Material exhibits significant plastic deformation
• Deformation in material is negligible
• Rapid deformation and fractures
• Material becomes more brittle and fails instantly

Explanation:

• Creep becomes important at elevated temperatures, especially above approximately 0.5 of the absolute melting temperature.

Why does cast iron have high compressive strength but low tensile strength?

• Due to its elastic properties
• Due to the presence of graphite flakes
• Due to its ductile nature
• Due to its high malleability

Explanation:

• Graphite flakes act as stress concentrators and cracks can propagate readily under tensile loading, reducing tensile strength.

Which type of steel would be best suited for applications requiring both high strength and good corrosion resistance?

• High-carbon steel
• Stainless steel
• Mild steel
• Low-alloy steel

Explanation:

• Stainless steel contains sufficient chromium to form a protective passive oxide layer, providing good corrosion resistance along with useful strength.

Which region of the stress-strain curve represents work hardening in ductile materials?

• D-E
• E-F
• C-D
• A-C

Explanation:

• Work hardening occurs after yielding and before ultimate tensile stress. In the given curve this is the D-E region.

Thermal stress in a composite bar does NOT depend on which of the following factors?

• Coefficient of thermal expansion
• Temperature change
• Modulus of elasticity
• Area of cross-section

Explanation:

• For a fully restrained member, thermal stress is related to EαΔT and does not directly depend on cross-sectional area.

The modulus of resilience is characterised by the area under the stress-strain curve up to the:

• Ultimate point
• Proportional limit
• Point where strain hardening starts
• Fracture point

Explanation:

• Modulus of resilience represents the elastic strain energy stored per unit volume up to the elastic limit; in the ideal linear elastic region it is taken up to the proportional limit.

Determine the minimum thickness of the rectangular axial bar shown against yielding. Given FOS = 2 and yield stress = 310 MPa.

• 25 mm
• 60 mm
• 155 mm
• 19.4 mm

Explanation:

• Allowable stress = 310/2 = 155 MPa. Using the shown width of 40 mm, t = 120000/(155 × 40) ≈ 19.4 mm.

If elastic strength increases 3 times, then proof resilience:

• Increases 9 times
• Increases 3 times
• Decreases 9 times
• Decreases 3 times

Explanation:

• Proof resilience is proportional to the square of elastic strength for constant modulus of elasticity. Therefore, 3² = 9 times.

A steel bar (E = 200 GPa, α = 12 × 10⁻⁶/°C) expands by 0.3 mm due to a temperature increase. If the original length was 15 cm, what was the temperature rise?

• 166.6°C
• 100°C
• 120.6°C
• 180°C

Explanation:

• Using ΔL = αLΔT, ΔT = 0.3/(12 × 10⁻⁶ × 150) ≈ 166.6°C.

When a body is subjected to two equal and opposite pulls, causing it to extend in length, the stress and strain induced are:

• Tensile stress and compressive strain
• Compressive stress and tensile strain
• Tensile stress and tensile strain
• Compressive stress and compressive strain

Explanation:

• Opposite outward pulls produce tension, causing elongation and therefore tensile strain.

_____ is a beam with one end fixed and the other end simply supported.

• Fixed beam
• Continuous beam
• Propped cantilever beam
• Over-hanging beam

Explanation:

• A propped cantilever has one end fixed and the other end supported by a simple support or prop.

The hoop stress developed in thin cylinders is given by:

• Pd/3t
• Pd/2t
• Pd/t
• Pd/4t

Explanation:

• For a thin cylindrical pressure vessel, hoop stress σ_h = Pd/(2t).

Which statement best describes a special-purpose lathe used for heavy-duty applications?

• A T-lathe is used for machining flat plates and sheet metal components
• A missile lathe is designed for lightweight parts with small diameters
• A wheel lathe is designed for machining railway wheels, including journals and treads
• A gap-bed lathe is mainly used for cutting small, high-precision components

Explanation:

• Wheel lathes are specially designed for machining railway wheels and related wheel surfaces.

What is the primary function of the headstock in a lathe machine?

• To control the movement of the carriage and tailstock
• To hold and rotate the workpiece at different speeds
• To provide support for cutting tools during operation
• To adjust the feed mechanism for thread-cutting

Explanation:

• The headstock houses the spindle and driving mechanism that rotates the workpiece.

What is the primary function of the tailstock in a lathe?

• To hold the cutting tool for machining operations
• To change the direction of spindle movement
• To provide support and bearing for the rotating job
• To control the speed of spindle rotation

Explanation:

• The tailstock supports the free end of long workpieces and can also hold tools such as drills and reamers.

What is the primary function of the tool post in a lathe machine?

• To support the compound rest and provide rotational movement
• To control the feed rate and depth of cut
• To hold and adjust the tool for a suitable working position
• To secure the workpiece firmly on the machine bed

Explanation:

• The tool post securely holds the cutting tool and permits adjustment of its position.

Lathe bed is made up of:

• High carbon steel
• High alloy steel
• Mild steel
• Cast iron

Explanation:

• Lathe beds are generally made from cast iron because of its rigidity, vibration damping and good wear resistance.

_____ is fitted on the top of the cross slide and is used to support the tool post and cutting tool.

• Carriage
• Tailstock
• Compound rest
• Saddle

Explanation:

• The compound rest is mounted on the cross-slide and supports the tool post.

The capacity of a lathe is expressed as:

• Horsepower and chuck diameter
• Tool post size and lathe travel
• Swing and distance between centres
• Bed length and spindle speed

Explanation:

• Lathe capacity is commonly specified by swing over the bed and maximum distance between centres.

_____ is the process of making flat surfaces on a lathe.

• Facing
• Reaming
• Drilling
• Boring

Explanation:

• Facing produces a flat surface perpendicular to the axis of rotation of the workpiece.

The largest diameter of work that can be carried between the centres of a lathe is known as:

• Saddle
• Swing
• Socket
• Spindle

Explanation:

• Swing represents the maximum diameter of work that can rotate without interference with the lathe bed or other parts.

In the up-milling process, the metal is removed in the form of small chips by a cutter rotating:

• In the same direction as the feed of the workpiece
• Metal will not be removed in the milling process
• Against the direction of travel of the workpiece
• Perpendicular to the direction of travel of the workpiece

Explanation:

• In up-milling, cutter rotation at the point of contact is opposite to the direction of workpiece feed.

Which of the following is the primary element that supports the workpiece in centreless grinding?

• Work rest blade
• Stationary table
• Work test blade
• Pressure roller blade

Explanation:

• The work rest blade supports the workpiece between the regulating and grinding wheels.

Which expression determines the longitudinal feed rate in through-feed centreless grinding?

• Longitudinal feed rate = π × D × N × sin(θ)
• Longitudinal feed rate = π × D × N × cos(θ)
• Longitudinal feed rate = (π × D × N)/cos(θ)
• Longitudinal feed rate = (π × D × N)/sin(θ)

Explanation:

• In through-feed centreless grinding, the axial feed is the axial component of the regulating wheel surface velocity.

Which of the following is NOT a mechanical finishing process?

• Shot peening
• Buffing
• Burnishing
• Pickling

Explanation:

• Pickling is a chemical surface-cleaning process, whereas shot peening, buffing and burnishing are mechanical processes.

Which is the correct sequence for the IS specification of a grinding wheel?

• Abrasive used – Structure – Grade – Grit number – Bond Type
• Abrasive used – Grit number – Grade – Structure – Bond Type
• Abrasive used – Grade – Structure – Grit number – Bond Type
• Abrasive used – Grit number – Structure – Grade – Bond Type

Explanation: Grinding-wheel specifications identify the abrasive, grain size, grade, structure and bond.

Which of the following wheels supports the workpiece in internal centreless grinding operation?

• Only pressure roller
• Only regulating wheel
• Only supporting roller
• Pressure roller, supporting roller and regulating wheel

Explanation: Internal centreless grinding requires suitable supporting and regulating elements to locate and rotate the internal workpiece.

What is the full form of CBN, which is used as an abrasive in grinding processes?

• Copper boron nitride
• Carbon boron nitrate
• Calcium bi nitrous
• Cubic boron nitride

Explanation: CBN stands for cubic boron nitride and is a very hard abrasive used particularly for hardened ferrous materials.

Which element provides the necessary horizontal force to the workpiece in centreless grinding?

• Regulating wheel
• Stationary wheel
• Revolving wheel
• Work rest blade

Explanation: The regulating wheel controls the rotational speed and provides the required feed of the workpiece.

What is the designated function of a planetary internal grinder machine?

• For a very small workpiece
• For a workpiece of regular shape
• For low-precision surface finishes
• For a workpiece of irregular shape

Explanation: Planetary internal grinding is useful for large or irregularly shaped components where conventional internal grinding is difficult.

Which of the following is used to check the diameters of holes?

• Plug gauge
• Fillet gauge
• Standard screw pitch gauge
• Slip gauge

Explanation: Plug gauges are used for checking the size of holes, particularly in go/no-go inspection.

How many divisions are graduated on the thimble of a micrometer?

• 40
• 50
• 15
• 25

Explanation: A conventional metric micrometer commonly has 50 divisions on its thimble.

Feeler gauges are used to:

• Check and measure bearing clearance
• All of the options
• Check and set spark plug gaps
• Check the gap between mating parts

Explanation: Feeler gauges are used to measure small clearances, including bearing and spark-plug gaps.

The preferred instrument for measuring the depth of holes, slots and recesses is:

• Vernier depth gauge
• Feeler gauge
• Screw gauge
• Vernier caliper

Explanation: A vernier depth gauge is specifically designed to measure the depth of holes, slots and recesses accurately.

A radius gauge is also known as:

• Fillet gauge
• Snap gauge
• Feeler gauge
• Slip gauge

Explanation: Radius gauges are also called fillet gauges and are used to check concave and convex radii.

The term ‘grating’ in metrology means that:

• Rulings follow a logarithmic scale
• Rulings need not have any pattern
• Rulings are more closely spaced, producing a periodic pattern without blank gaps
• Rulings are spaced relatively far apart, requiring interpolation

Explanation: A grating consists of a regular periodic arrangement of closely spaced lines or rulings.

Johannsen gauges are otherwise known as:

• Slip gauges
• Radius gauges
• Snap gauges
• Feeler gauges

Explanation: Johannsson or Johansson gauges are precision slip gauges used as standards of length.

For which surface is a spirit level used for testing straightness?

• Inclined surfaces
• Horizontal surfaces
• Both horizontal and vertical surfaces
• Vertical surfaces

Explanation: A spirit level is commonly used to check the straightness or level condition of horizontal surfaces.

In a vernier caliper, the main scale reads in millimeters. Ten divisions on the vernier correspond to nine divisions of the main scale. Determine the least count.

• 0.01 mm
• 0.001 mm
• 0.1 mm
• 1 mm

Explanation: If 10 vernier divisions equal 9 main-scale divisions, the difference between one main-scale division and one vernier division gives a least count of 0.01 mm for a 1-mm main-scale division.

While taking a measurement with a micrometer, which two parts are used to hold the specimen?

• Spindle and anvil
• Spindle and ratchet
• Anvil and ratchet
• Anvil and barrel

Explanation: The workpiece is held between the fixed anvil and the movable spindle during measurement.

The length of the slot weld can be obtained from the ratio of:

• Allowable stress to load
• Load to allowable stress
• Allowable stress to weld area
• Weld area to allowable stress

Explanation: Weld area is obtained from load divided by allowable stress; the required slot length is then determined using the effective weld dimensions.

The distance from the joint root to the toe of the weld is called:

• Face
• Leg
• Effective throat
• Actual throat

Explanation: In a fillet weld, the leg is the distance from the root to the toe along the respective base-metal surfaces.

The distance that fusion extends into the base metal or previous pass from the surface melted during welding is known as:

• Deposition thickness
• Dilution
• Cold lap
• Depth of fusion

Explanation: Depth of fusion is the depth to which the base metal or previous weld pass has melted and fused.

The force applied on a body of mass 236 kg to produce an acceleration of 4 m/s² is:

• 59 N
• 472 N
• 944 N
• 118 N

Explanation: From F = ma, F = 236 × 4 = 944 N.

What is the full form of DCEP in arc welding?

• Direct Current Electrode Point
• Direct Current Electric Point
• Direct Current Electric Positive
• Direct Current Electrode Positive

Explanation: DCEP means direct current electrode positive, also called reverse polarity.

In overhead welding position, which is the correct option?

• Work pieces lie flat and welding is done from the upper side
• Welding is performed from the underside of the joint
• This position is the simplest operation compared with flat position
• It is most suitable for submerged arc process

Explanation: In overhead welding, the weld is made on the underside of the joint while the welder works below it.

Plain and butt welds may be used on materials up to approximately:

• 25 mm thick
• 40 mm thick
• 50 mm thick
• 70 mm thick

Explanation: Plain and butt welds are commonly used for plates up to approximately 25 mm thickness in the context of the given question.

In a single V-butt weld, the angle between edges is kept about:

• 40° to 60°
• 70° to 90°
• 10° to 20°
• 20° to 40°

Explanation: A suitable included angle is provided in a single-V butt joint to permit proper electrode access and penetration.

Which of the following is true regarding a T-joint weld?

• It is used where severe loading is encountered and both upper surfaces must be in the same plane
• It is used to join two pieces in the manner of a rivet joint
• It is used to join two pieces perpendicularly
• It is used where longitudinal shear is present

Explanation: A T-joint joins two members approximately at right angles, forming a T-shaped arrangement.

What should be the size of weld in case of a butt-welded joint?

• Twice the throat of weld
• Half of the throat of weld
• Equal to the throat of weld
• None of the above

Explanation: For the idealized butt-weld terminology used in the question, the weld size is taken as the effective throat dimension.

The value of density of water at room temperature is:

• 10 g/cm³ or 10000 kg/m³
• 1 g/cm³ or 1000 kg/m³
• 3 g/cm³ or 3000 kg/m³
• 2 g/cm³ or 2000 kg/m³

Explanation: The density of water is approximately 1000 kg/m³ or 1 g/cm³ near room temperature.

Specific volume of a fluid is the reciprocal of its:

• Surface tension
• Viscosity
• Dynamic viscosity
• Mass density

Explanation: Specific volume v is defined as volume per unit mass, so v = 1/ρ.

Which of the following forces act in a moving fluid?

• Inertia force
• Viscous force
• All of the options
• Gravity force

Explanation: Depending on the flow situation, inertia, viscous and gravity forces may all act on a moving fluid.

Mercury does NOT wet glass. This is due to the property of the liquid known as:

• Cohesion
• Surface tension
• Viscosity
• Adhesion

Explanation: Strong cohesive forces between mercury molecules compared with adhesive forces between mercury and glass cause mercury to form a convex meniscus and not wet glass.

Paper pulp can be regarded as:

• Dilatant fluid
• Pseudoplastic fluid
• Newtonian fluid
• Bingham plastic fluid

Explanation: Paper pulp behaves as a non-Newtonian material requiring a finite yield stress before significant flow occurs.

What is the unit of pressure?

• Pascal
• Kilogram
• Newton
• Kelvin

Explanation: The SI unit of pressure is the pascal (Pa), equal to one newton per square metre.

What is the mass of a unit volume of a substance called?

• Density
• Pressure
• Buoyancy
• Force

Explanation: Density is defined as mass per unit volume, ρ = m/V.

The coefficient of velocity is defined as the ratio of the:

• Area of jet at vena contracta to the area of orifice
• Actual velocity of jet at vena contracta to the theoretical velocity
• Actual discharge through an orifice to theoretical discharge
• Actual discharge through an orifice to area of orifice

Explanation: Coefficient of velocity C_v = actual velocity/theoretical velocity.

What percentage of the total volume of an iceberg floats above the water surface? Assume density of ice = 920 kg/m³ and density of water = 1000 kg/m³.

• 6%
• 8%
• 20%
• 92%

Explanation: Fraction submerged = 920/1000 = 0.92. Therefore, fraction above water = 1 − 0.92 = 0.08 = 8%.

One Poiseuille is equivalent to ______ poise.

• 100
• 1000
• 1
• 10

Explanation: 1 Poiseuille = 1 Pa·s = 10 poise.

According to Herzberg’s Two-Factor Theory, the hygiene factor that leads to job dissatisfaction is:

• Achievement
• Salary
• Responsibility
• Recognition

Explanation: Salary is classified as a hygiene factor. Poor hygiene factors can contribute to job dissatisfaction.

G-ratio varies from ______ in very rough grinding.

• 11.0 to 15.0
• 16.0 to 20.0
• 1.0 to 5.0
• 6.0 to 10.0

Explanation: G-ratio is the ratio of material removed from the workpiece to the volume of grinding wheel wear. Rough grinding generally has a lower G-ratio.

The Zeroth Law of Thermodynamics establishes the basis for which of the following?

• Entropy increase in isolated systems
• Measurement of temperature
• Conservation of energy
• Heat transfer through conduction

Explanation: The Zeroth Law establishes thermal equilibrium and provides the fundamental basis for defining and measuring temperature.

Which of the following is an exothermic process?

• Sublimation of camphor
• All of the options
• Evaporation of water
• Reaction of water with quick lime

Explanation: Quick lime (CaO) reacts with water to form calcium hydroxide and releases heat: CaO + H₂O → Ca(OH)₂.

Which of the following materials is likely to have the highest thermal conductivity?

• Aluminium
• Rubber
• Air
• Wood

Explanation: Aluminium is a good thermal conductor, whereas rubber, air and wood have much lower thermal conductivity.

The unit of overall coefficient of heat transfer is:

• W/m² K
• W/m²
• W/mK
• W/m

Explanation: The overall heat-transfer coefficient U has SI unit W/(m²·K).

The thermal diffusivity is given by the expression [k = thermal conductivity, ρ = density, C_p = specific heat capacity]:

• k/(ρC_p)
• ρC_p/k
• kρC_p
• ρ/(kC_p)

Explanation: Thermal diffusivity α = k/(ρC_p). It indicates how quickly temperature changes propagate through a material.

The reversed Carnot cycle is used as a basis for which of the following?

• Heat engines
• Internal combustion engines
• Refrigerators and heat pumps
• Steam turbines

Explanation: The reversed Carnot cycle represents the ideal limiting performance of refrigeration and heat-pump systems.

In a four-stroke diesel engine, the exhaust valve opens before the piston reaches Bottom Dead Center to:

• Improve fuel atomization
• Reduce pumping losses
• Enhance air-fuel mixing
• Increase the compression ratio

Explanation: Early exhaust-valve opening allows cylinder pressure to fall before the exhaust stroke, reducing the work required to expel exhaust gases.

In a two-stroke petrol engine, which of the following best describes the sequence of events during an exhaust stroke?

• Both ports open simultaneously
• The exhaust port opens and closes before the transfer port opens
• The transfer port opens first, followed by the exhaust port
• The exhaust port opens first, followed by the transfer port

Explanation: During scavenging of a typical two-stroke engine, the exhaust port opens before the transfer port so that combustion gases begin leaving the cylinder before fresh charge enters.

In a two-stroke petrol engine, the primary function of the crankcase is to:

• Cool the engine
• Act as a primary pumping chamber for the air-fuel mixture
• Store lubricating oil
• House the transfer port

Explanation: In a crankcase-scavenged two-stroke petrol engine, the descending piston compresses the fresh charge in the crankcase before it enters the cylinder.

In a four-stroke cycle, the minimum temperature inside the engine cylinder occurs at the:

• Beginning of exhaust stroke
• Beginning of suction stroke
• End of exhaust stroke
• End of suction stroke

Explanation: After exhaust gases have been expelled and before significant compression begins, the cylinder temperature is at its minimum in the ideal cycle description.

In a four-stroke engine, the working cycle is completed in:

• One revolution of the crankshaft
• Two revolutions of the crankshaft
• Three revolutions of the crankshaft
• Four revolutions of the crankshaft

Explanation: A four-stroke engine completes suction, compression, power and exhaust in four strokes, requiring two crankshaft revolutions.

For each crankshaft revolution, the camshaft revolves:

• One-half turn
• Two turns
• Four turns
• As many turns as the number of valves

Explanation: In a four-stroke engine, the camshaft rotates at half the speed of the crankshaft.

What is the material of a connecting rod?

• Mild steel
• Forged steel
• Tool steel
• Cast iron

Explanation: Connecting rods are commonly manufactured from forged steel because of its high strength and ability to withstand cyclic loads.

Stroke of an engine is:

• Volume of the cylinder
• Length of the connecting rod
• Internal diameter of cylinder
• Distance between TDC and BDC

Explanation: Engine stroke is the linear distance travelled by the piston between Top Dead Centre and Bottom Dead Centre.

A certain engine produces 10 kW indicated power. Its mechanical efficiency is 70%. Then the frictional power is:

• 2 kW
• 2.5 kW
• 3 kW
• 3.5 kW

Explanation: Mechanical efficiency = BP/IP. Therefore BP = 0.7 × 10 = 7 kW. Friction power = IP − BP = 10 − 7 = 3 kW.

Morse test is applicable only for:

• Single-cylinder SI engines
• Single-cylinder CI engines
• Multi-cylinder CI engines
• Multi-cylinder SI and CI engines

Explanation: The Morse test is used to determine friction power in multi-cylinder engines by successively cutting out individual cylinders while maintaining constant speed.