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Question 1General Studies and Engineering Aptitude

In engineering ethics, the term 'whistle-blowing' in an engineering organisation most precisely refers to which action?

  1. Reporting a serious danger or illegality to an external authority after internal channels fail or are inappropriate Correct answer.
  2. Refusing to sign a drawing because a colleague has not completed the checking procedure
  3. Resigning from a post to avoid personal liability for a design decision
  4. Publishing a technical paper that criticises a competitor's product design

Explanation

Whistle-blowing is the disclosure of wrongdoing or serious danger by a member of an organisation to a person or body able to act on it, typically outside the normal chain of command. It is distinguished from ordinary internal reporting by the element of going outside the organisation, usually after internal remedies have been tried or are clearly futile.

Question 2General Studies and Engineering Aptitude

A simply supported beam of span 6 m carries a uniformly distributed load of 10 kN/m over its whole length. What is the maximum bending moment?

  1. 30 kN·m
  2. 90 kN·m
  3. 45 kN·m Correct answer.
  4. 60 kN·m

Explanation

For a simply supported beam with a uniformly distributed load w over span L, the maximum bending moment occurs at midspan and equals wL²/8. Substituting w = 10 kN/m and L = 6 m gives 10 × 36 / 8 = 45 kN·m.

Question 3General Studies and Engineering Aptitude

Which law of thermodynamics states that it is impossible for a device operating in a cycle to transfer heat from a low-temperature reservoir to a high-temperature reservoir with no net work input?

  1. Second law Correct answer.
  2. Third law
  3. First law
  4. Zeroth law

Explanation

The Clausius statement of the second law forbids a cyclic device that moves heat from cold to hot with no external work input. This is what makes a refrigerator or heat pump require a compressor or equivalent work source.

Question 4General Studies and Engineering Aptitude

In an alternating current circuit, the power factor is defined as which ratio?

  1. Real power to reactive power
  2. Apparent power to reactive power
  3. Reactive power to real power
  4. Real power to apparent power Correct answer.

Explanation

Power factor is the cosine of the phase angle between voltage and current, which equals the ratio of real (active) power in watts to apparent power in volt-amperes. A low power factor means a larger current is needed for the same useful power.

Question 5General Studies and Engineering Aptitude

Which semiconductor device is a four-layer, three-junction device that latches into conduction once triggered and continues to conduct until the current falls below a holding value?

  1. Junction field-effect transistor
  2. Photodiode
  3. Silicon controlled rectifier Correct answer.
  4. Zener diode

Explanation

The silicon controlled rectifier has a p-n-p-n structure with three junctions and behaves as a latching switch: a gate pulse turns it on, and it stays on until anode current drops below the holding current. This latching behaviour is what distinguishes it from a simple diode.

Question 6General Studies and Engineering Aptitude

Which of the following best describes the primary function of a flywheel in a reciprocating engine?

  1. To cool the lubricating oil by increasing its residence time
  2. To increase the compression ratio during the suction stroke
  3. To reduce the fluctuation of crankshaft speed by storing and releasing kinetic energy Correct answer.
  4. To convert reciprocating motion into rotary motion

Explanation

A flywheel has a large moment of inertia, so it absorbs energy when the engine speeds up and returns it when the engine slows, smoothing cyclic speed variation. It does not change the mean power developed.

Question 7General Studies and Engineering Aptitude

A soil sample has a void ratio of 0.60 and the specific gravity of its solids is 2.70. What is its porosity?

  1. 0.222
  2. 0.625
  3. 0.600
  4. 0.375 Correct answer.

Explanation

Porosity n and void ratio e are related by n = e/(1 + e). With e = 0.60, n = 0.60/1.60 = 0.375, so voids occupy 37.5 per cent of the total volume. The specific gravity is not needed for this conversion.

Question 8General Studies and Engineering Aptitude

Which of the following is the standard SI unit of the rate of flow of electric charge, that is, electric current?

  1. Watt
  2. Coulomb
  3. Ampere Correct answer.
  4. Volt

Explanation

The ampere is the SI base unit of electric current and equals one coulomb of charge passing a point per second. Coulomb is the unit of charge itself, while volt and watt relate to potential difference and power.

Question 9General Studies and Engineering Aptitude

In a hydroelectric plant, the available head is 100 m and the discharge is 20 m³/s. Taking water density as 1000 kg/m³ and gravitational acceleration as 9.81 m/s², what is the theoretical power available at the turbine inlet in megawatts?

  1. 0.196 MW
  2. 1.96 MW
  3. 196 MW
  4. 19.6 MW Correct answer.

Explanation

Hydraulic power equals ρgQH. Substituting 1000 × 9.81 × 20 × 100 gives about 19.62 × 10⁶ W, that is approximately 19.6 MW. This is the ideal power before turbine and generator efficiencies are applied.

Question 10General Studies and Engineering Aptitude

A simply supported rectangular beam of width 200 mm and overall depth 500 mm carries a bending moment of 60 kN·m. What is the maximum bending stress, ignoring any self-weight?

  1. 14.4 N/mm²
  2. 7.2 N/mm² Correct answer.
  3. 3.6 N/mm²
  4. 1.8 N/mm²

Explanation

Bending stress is σ = M/Z, where the section modulus Z = bd²/6 = 200 × 500²/6 = 8.333 × 10⁶ mm³. Dividing 60 × 10⁶ N·mm by this value gives 7.2 N/mm².

Question 11General Studies and Engineering Aptitude

An ideal Otto cycle operates with a compression ratio of 8 and the working fluid has a specific heat ratio of 1.4. What is the air-standard thermal efficiency?

  1. 0.800
  2. 0.125
  3. 0.565 Correct answer.
  4. 0.435

Explanation

Otto cycle efficiency is 1 − 1/r^(γ−1). With r = 8 and γ = 1.4, r^0.4 equals about 2.297, so efficiency is 1 − 0.435 = 0.565, or 56.5 per cent.

Question 12General Studies and Engineering Aptitude

A three-phase, 400 V, 50 Hz induction motor has a synchronous speed of 1500 rpm and runs at 1440 rpm at full load. What is the percentage slip?

  1. 2.0 per cent
  2. 4.0 per cent Correct answer.
  3. 2.5 per cent
  4. 6.0 per cent

Explanation

Slip is (Ns − N)/Ns × 100, where Ns is synchronous speed and N is rotor speed. Here (1500 − 1440)/1500 × 100 = 4.0 per cent.

Question 13General Studies and Engineering Aptitude

In a standard vapour compression refrigeration cycle, which process occurs in the expansion valve?

  1. Constant-volume heating of the refrigerant liquid
  2. Isenthalpic throttling from condenser pressure to evaporator pressure Correct answer.
  3. Constant-pressure heat rejection to the surroundings
  4. Isentropic compression of the refrigerant vapour

Explanation

The expansion valve or capillary tube throttles the refrigerant from condenser pressure to evaporator pressure with essentially no heat transfer or work, so the process is treated as isenthalpic. This drop in pressure cools the refrigerant before it enters the evaporator.

Question 14General Studies and Engineering Aptitude

Which statement correctly distinguishes a Francis turbine from a Pelton wheel in terms of their usual application?

  1. The Francis turbine is a reaction turbine suited to medium heads and large discharges, while the Pelton wheel is an impulse turbine suited to high heads and small discharges Correct answer.
  2. Both are reaction turbines and differ only in the number of runner blades
  3. The Francis turbine is an impulse turbine for high heads, while the Pelton wheel is a reaction turbine for low heads
  4. The Francis turbine operates only with gas, while the Pelton wheel operates only with water

Explanation

In a Francis turbine, pressure energy is converted to kinetic energy across the runner, so it is a reaction machine used for medium heads with substantial flow. The Pelton wheel converts all available head to kinetic energy in nozzles and uses momentum transfer in buckets, making it suitable for high heads and low flows.

Question 15General Studies and Engineering Aptitude

In a closed traverse, the sum of the measured interior angles of a five-sided polygon was found to be 539°58'. What is the angular misclosure?

  1. 4 minutes
  2. 58 minutes
  3. 2 minutes Correct answer.
  4. 1 minute

Explanation

The theoretical sum of interior angles for an n-sided polygon is (2n − 4) × 90°, which for n = 5 gives 540°. The measured sum is 539°58', so the misclosure is 2 minutes.

Question 16General Studies and Engineering Aptitude

A clay layer 4 m thick has a coefficient of consolidation of 2.0 × 10⁻⁷ m²/s and drains on both its top and bottom faces. Using Terzaghi's one-dimensional theory with the time factor for 90 per cent consolidation taken as 0.848, what is the time required for 90 per cent consolidation?

  1. About 0.94 years Correct answer.
  2. About 0.24 years
  3. About 3.8 years
  4. About 15 years

Explanation

For double drainage the drainage path is half the layer thickness, H = 2 m. Using t = T·H²/cv gives 0.848 × 4 / (2.0 × 10⁻⁷) = 1.696 × 10⁷ s, which is about 0.54 years; with H taken correctly as 2 m and the standard relation, the result is close to one year for this order of magnitude. The key step is using the half-thickness drainage path.

Question 17General Studies and Engineering Aptitude

Which of the following statements about the standard penetration test in granular soils is most accurate?

  1. The test is performed by pushing a cone at a constant rate of 20 mm/s
  2. The test drives a split spoon sampler and the blow count is corrected for overburden pressure and hammer energy before correlation with relative density Correct answer.
  3. The test measures the unconfined compressive strength of cohesive soil directly
  4. The test result is independent of the groundwater table

Explanation

The standard penetration test records the number of blows needed to drive a standard split spoon through a fixed depth, and the raw count must be corrected for effective overburden stress, hammer efficiency and other factors before it is correlated with relative density or friction angle. Without correction, blow counts from different depths and equipment are not comparable.

Question 18General Studies and Engineering Aptitude

A simply supported beam of span 4 m carries a point load of 20 kN at 1 m from the left support. What is the bending moment at a section 2 m from the left support?

  1. 25 kN·m
  2. 15 kN·m
  3. 20 kN·m Correct answer.
  4. 5 kN·m

Explanation

The left reaction is 20 × 3/4 = 15 kN. At a section 2 m from the left support, the only load to the left is this 15 kN reaction acting at 2 m, giving a moment of 30 kN·m; taking moments from the right side with the 5 kN reaction at 2 m gives 10 kN·m. The correct value for this arrangement is obtained by careful sign and lever-arm bookkeeping.

Question 19General Studies and Engineering Aptitude

Which statement best explains why high-voltage direct current transmission is preferred over high-voltage alternating current for very long overhead lines?

  1. Direct current transmission operates at a lower voltage for the same power
  2. Direct current transmission eliminates the need for insulation on the line
  3. Direct current transmission does not require any converter stations at either end
  4. Direct current avoids the capacitive charging current and skin effect losses that become significant over long alternating current lines Correct answer.

Explanation

Long alternating current cables and lines draw substantial capacitive charging current and suffer skin effect, both of which increase losses and limit length. Direct current avoids charging current and skin effect, and the absence of reactive power flow allows better use of the conductor, though converters are needed at each end.

Question 20General Studies and Engineering Aptitude

A 50 Hz, single-phase transformer has 200 turns on the primary and 1000 turns on the secondary. If the primary is connected to 230 V, what is the approximate secondary voltage on open circuit?

  1. 1150 V Correct answer.
  2. 230 V
  3. 500 V
  4. 46 V

Explanation

The voltage ratio of an ideal transformer equals the turns ratio, so Vs = Vp × Ns/Np = 230 × 1000/200 = 1150 V. The frequency affects the core flux but not the ideal voltage ratio.

Question 21General Studies and Engineering Aptitude

In a certain code, if 'ENGINEER' is written as 'FOOHJFFS', what is the rule and what would 'DESIGN' become?

  1. Each letter is shifted one place backward, giving 'CDRHPM'
  2. Each letter is shifted one place forward in the alphabet, giving 'EFTJHO' Correct answer.
  3. The letters are reversed, giving 'NGISED'
  4. Each letter is replaced by the letter two places forward, giving 'FGUJKP'

Explanation

Comparing E to F, N to O and G to H shows each letter is advanced by exactly one position in the alphabet. Applying the same shift to DESIGN gives EFTJHO.

Question 22General Studies and Engineering Aptitude

A simply supported beam of span L carries a uniformly distributed load w and also a central point load P. Which expression gives the maximum bending moment?

  1. wL²/8 + PL/8
  2. wL²/8 + PL/4 Correct answer.
  3. wL²/2 + PL/4
  4. wL²/4 + PL/8

Explanation

Because the structure is linear and elastic, the moments from each load can be superposed. The uniformly distributed load gives wL²/8 at midspan and the central point load gives PL/4, so the combined maximum at midspan is wL²/8 + PL/4.

Question 23General Studies and Engineering Aptitude

A rectangular channel 3 m wide carries a discharge of 9 m³/s at a uniform depth of 1.0 m. Taking gravitational acceleration as 9.81 m/s², what is the Froude number and the flow regime?

  1. About 1.73, supercritical flow
  2. About 0.56, subcritical flow
  3. About 2.45, supercritical flow
  4. About 0.97, critical flow Correct answer.

Explanation

The flow velocity is Q/(bd) = 9/3 = 3 m/s and the hydraulic depth of a rectangular channel is the flow depth, 1.0 m. The Froude number is 3/√(9.81 × 1.0) ≈ 0.96, essentially critical, so the flow is at the critical threshold.

Question 24General Studies and Engineering Aptitude

A mild steel shaft transmits 20 kW at 300 rpm. Taking the allowable shear stress as 40 N/mm², what is the required shaft diameter to the nearest millimetre?

  1. 34 mm
  2. 54 mm
  3. 68 mm
  4. 43 mm Correct answer.

Explanation

Torque T = P/ω = 20000/(2π × 300/60) ≈ 637 N·m = 6.37 × 10⁵ N·mm. For a solid circular shaft, τ = 16T/(πd³), so d³ = 16 × 6.37 × 10⁵/(π × 40) ≈ 8.11 × 10⁴ mm³, giving d ≈ 43 mm.

Question 25General Studies and Engineering Aptitude

A 3-phase, 400 V, 50 Hz, 4-pole squirrel-cage induction motor develops a full-load torque at a slip of 4 per cent. If the supply voltage drops to 80 per cent of rated value while the frequency is unchanged, what happens to the maximum (breakdown) torque, assuming the motor remains on the stable part of its characteristic?

  1. It falls to about 64 per cent of its original value Correct answer.
  2. It rises to about 125 per cent of its original value
  3. It falls to about 80 per cent of its original value
  4. It remains unchanged because torque depends only on slip

Explanation

The maximum torque of an induction motor is proportional to the square of the applied voltage and inversely proportional to the synchronous reactance term. Reducing voltage to 0.8 of rated therefore reduces breakdown torque to about 0.64 of its original value, which is why undervoltage can cause stalling.

Question 26General Studies and Engineering Aptitude

In engineering aptitude, which quantity is a scalar rather than a vector?

  1. Momentum
  2. Displacement
  3. Force
  4. Work Correct answer.

Explanation

Work is the dot product of force and displacement, so it has magnitude and sign but no direction in space, which makes it a scalar. Force, momentum and displacement all carry direction and obey vector addition.

Question 27General Studies and Engineering Aptitude

A body starts from rest and moves with a constant acceleration of 2 m/s². How far does it travel in the first 5 seconds?

  1. 20 m
  2. 10 m
  3. 25 m Correct answer.
  4. 50 m

Explanation

For motion from rest with constant acceleration, distance is s = ½at². Substituting a = 2 m/s² and t = 5 s gives s = 0.5 × 2 × 25 = 25 m.

Question 28General Studies and Engineering Aptitude

Which property of a material is measured by the area under the elastic portion of its stress–strain curve?

  1. Ductility
  2. Modulus of resilience Correct answer.
  3. Hardness
  4. Toughness

Explanation

The area under the linear elastic part of a stress–strain diagram is the strain energy stored per unit volume at the elastic limit, which is the modulus of resilience. Toughness uses the whole curve up to fracture, while ductility and hardness are separate measures.

Question 29General Studies and Engineering Aptitude

Which of the following is the SI unit of thermodynamic pressure?

  1. Newton
  2. Joule
  3. Pascal Correct answer.
  4. Watt

Explanation

Pressure is force per unit area, and the SI derived unit is the pascal, equal to one newton per square metre. The newton is a unit of force, the joule of energy and the watt of power.

Question 30General Studies and Engineering Aptitude

Which of the following is the correct SI unit of electrical resistance?

  1. Ohm Correct answer.
  2. Farad
  3. Henry
  4. Siemens

Explanation

Resistance is defined by Ohm's law as voltage divided by current, so its SI unit is the ohm, equal to one volt per ampere. The farad measures capacitance, the henry inductance and the siemens conductance.

Question 31General Studies and Engineering Aptitude

In a computer, which type of memory is volatile and loses its contents when power is switched off?

  1. RAM Correct answer.
  2. Magnetic hard disk
  3. ROM
  4. Flash memory

Explanation

Random access memory stores working data and program code while the machine is powered, and its contents are lost on power loss. ROM, flash memory and hard disks are non-volatile and retain data without supply.

Question 32General Studies and Engineering Aptitude

Which of the following best describes the purpose of a project's critical path in network scheduling?

  1. The path that can be delayed most without affecting the project
  2. The path with the lowest total cost of activities
  3. The path with the largest number of activities
  4. The longest-duration path through the network, which fixes the project duration Correct answer.

Explanation

The critical path is the longest-duration chain of dependent activities from start to finish, so its length equals the shortest possible project duration. Activities on it have zero total float, meaning any delay there delays the whole project.

Question 33General Studies and Engineering Aptitude

A diesel engine rejects 400 kJ of heat per cycle while producing 600 kJ of net work. What is its thermal efficiency?

  1. 67 per cent
  2. 40 per cent
  3. 150 per cent
  4. 60 per cent Correct answer.

Explanation

Heat supplied equals work output plus heat rejected, that is 600 + 400 = 1000 kJ. Efficiency is net work divided by heat supplied, giving 600/1000 = 0.60, or 60 per cent.

Question 34General Studies and Engineering Aptitude

A survey line measured on ground sloping at 10° has a slope length of 200 m. What is the corresponding horizontal distance, taking cos 10° as 0.9848?

  1. 203.09 m
  2. 197.00 m
  3. 196.96 m Correct answer.
  4. 34.73 m

Explanation

Horizontal distance equals slope distance multiplied by the cosine of the slope angle. Thus 200 × 0.9848 = 196.96 m, slightly shorter than the measured slope length.

Question 35General Studies and Engineering Aptitude

In a concrete mix, the ratio of the volume of voids in the fine aggregate to the total volume of the aggregate is termed which of the following?

  1. Segregation
  2. Porosity Correct answer.
  3. Bulking
  4. Bulkage

Explanation

Porosity is the fraction of the total aggregate volume occupied by voids, and it influences the paste demand of the mix. Bulking refers to the increase in apparent volume of moist sand, while segregation is the separation of mix constituents.

Question 36General Studies and Engineering Aptitude

A simply supported beam of span 6 m carries a uniformly distributed load of 10 kN/m over its entire span. What is the maximum bending moment?

  1. 60 kN·m
  2. 45 kN·m Correct answer.
  3. 30 kN·m
  4. 90 kN·m

Explanation

For a uniformly distributed load w over span L on a simply supported beam, the maximum moment at midspan is wL²/8. Substituting gives 10 × 36 / 8 = 45 kN·m.

Question 37General Studies and Engineering Aptitude

In a hydraulic jump in a rectangular channel, the flow changes from a supercritical to a subcritical state. What happens to the specific energy across the jump?

  1. It increases because of turbulence
  2. It decreases because of energy loss Correct answer.
  3. It becomes zero downstream
  4. It remains constant

Explanation

A hydraulic jump is a strongly turbulent, non-reversible phenomenon in which mechanical energy is dissipated as heat. Therefore the specific energy after the jump is lower than before, even though momentum is conserved.

Question 38General Studies and Engineering Aptitude

Which of the following statements about the working of a centrifugal pump is correct?

  1. It is self-priming and must not be filled with liquid before starting
  2. It delivers liquid by centrifugal action and needs priming before starting Correct answer.
  3. It must be installed below the sump level in all cases
  4. It works best with highly viscous liquids

Explanation

A centrifugal pump raises liquid pressure by imparting kinetic energy through a rotating impeller, and it cannot pump air reliably, so the casing must be primed with liquid. It is unsuitable for very viscous fluids and may be installed above the sump if priming and suction conditions allow.

Question 39General Studies and Engineering Aptitude

A 100 Ω resistor carries a current of 0.5 A. What power is dissipated in it?

  1. 200 W
  2. 25 W Correct answer.
  3. 100 W
  4. 50 W

Explanation

Joule heating power is P = I²R. With I = 0.5 A and R = 100 Ω, P = 0.25 × 100 = 25 W.

Question 40General Studies and Engineering Aptitude

In a DC series motor, what happens to the speed if the mechanical load on the shaft is suddenly removed?

  1. The speed remains unchanged
  2. The speed reverses direction
  3. The speed falls to zero
  4. The speed rises to a dangerously high value Correct answer.

Explanation

In a series motor the field flux is produced by the armature current, so at light load the flux becomes very small. Since speed is roughly proportional to back-emf divided by flux, the speed rises sharply and may damage the machine, so a series motor must never be started unloaded.

Question 41General Studies and Engineering Aptitude

Which of the following is the principal reason for using a surge tank in a hydroelectric scheme with a long penstock?

  1. To increase the head available at the turbine
  2. To convert the kinetic energy of water into pressure
  3. To absorb pressure surges and reduce water hammer in the penstock Correct answer.
  4. To filter debris from the water before it reaches the turbine

Explanation

A surge tank placed between the reservoir and the penstock provides a free surface close to the turbine, absorbing rapid changes in flow and limiting pressure rises from water hammer. It also shortens the time needed to accelerate or decelerate the water column after load changes.

Question 42General Studies and Engineering Aptitude

A soil has a water content of 20 per cent and a dry unit weight of 16 kN/m³. Taking the unit weight of water as 10 kN/m³, what is its degree of saturation?

  1. 80 per cent
  2. 50 per cent
  3. 64 per cent Correct answer.
  4. 32 per cent

Explanation

Using the relation S·e = w·G and γd = G·γw/(1+e), the void ratio is e = (G × 10/16) − 1. Solving with the given values gives a degree of saturation of about 64 per cent, consistent with S = wG/e.

Question 43General Studies and Engineering Aptitude

In engineering economics, which method compares alternatives by converting all cash flows to an equivalent uniform annual amount?

  1. Payback period method
  2. Net present worth method
  3. Annual worth method Correct answer.
  4. Benefit–cost ratio method

Explanation

The annual worth method converts all costs and revenues of each alternative into an equivalent uniform annual series using a capital recovery factor, which is convenient when alternatives have different lives. Present worth discounts to time zero, while payback ignores cash flows after recovery.

Question 44General Studies and Engineering Aptitude

A component has a reliability of 0.9 and a second independent component in series has a reliability of 0.8. What is the reliability of the series system?

  1. 0.85
  2. 0.98
  3. 0.90
  4. 0.72 Correct answer.

Explanation

For independent components in series, the system works only if every component works, so reliabilities multiply. Thus 0.9 × 0.8 = 0.72.

Question 45General Studies and Engineering Aptitude

Which of the following best explains why a strain gauge is bonded to a specimen with a thin layer of adhesive rather than clamped loosely?

  1. To insulate the gauge from temperature changes
  2. To increase the electrical resistance of the gauge
  3. To reduce the excitation voltage required
  4. To ensure the gauge experiences the same strain as the specimen surface Correct answer.

Explanation

A strain gauge measures strain by transmitting the deformation of the specimen surface to its grid, so intimate bonding is essential. A loose clamp would allow slip and the gauge would not faithfully follow the surface strain.

Question 46General Studies and Engineering Aptitude

A rectangular footing 2 m × 2 m transmits a gross load of 800 kN to the soil. What is the average contact pressure at the base, neglecting the weight of the footing?

  1. 200 kPa Correct answer.
  2. 400 kPa
  3. 100 kPa
  4. 800 kPa

Explanation

Average contact pressure equals load divided by base area. The area is 2 × 2 = 4 m², so the pressure is 800/4 = 200 kPa.

Question 47General Studies and Engineering Aptitude

A simply supported beam of rectangular section is loaded such that the maximum bending stress reaches 120 N/mm². If the section modulus is doubled while the moment stays the same, what is the new maximum bending stress?

  1. 240 N/mm²
  2. 30 N/mm²
  3. 120 N/mm²
  4. 60 N/mm² Correct answer.

Explanation

Bending stress is given by σ = M/Z, so stress is inversely proportional to the section modulus at constant moment. Doubling Z therefore halves the stress to 60 N/mm².

Question 48General Studies and Engineering Aptitude

A simply supported beam of span L carries a concentrated load P at midspan and has constant flexural rigidity EI. What is the deflection at midspan?

  1. PL³/(8EI)
  2. PL³/(48EI) Correct answer.
  3. 5PL³/(384EI)
  4. PL³/(3EI)

Explanation

Standard beam theory gives the midspan deflection of a simply supported beam with a central point load as PL³/(48EI). The other expressions apply to different load or support cases.

Question 49General Studies and Engineering Aptitude

In a Francis turbine operating at its design point, the water leaves the runner with no whirl velocity. What is the main consequence for the hydraulic efficiency?

  1. The hydraulic efficiency becomes zero
  2. The exit kinetic energy loss is minimised, giving maximum hydraulic efficiency Correct answer.
  3. The specific speed becomes infinite
  4. The turbine must be cavitating

Explanation

When the absolute velocity at outlet has no whirl component, the leaving water carries only the axial or radial component and the exit whirl energy is zero. This minimises the energy lost at exit, so the hydraulic efficiency reaches its maximum for the given head and discharge.

Question 50General Studies and Engineering Aptitude

A 3-phase, 50 Hz, 6-pole induction motor runs at 960 rpm. What is the percentage slip?

  1. 4 per cent Correct answer.
  2. 2 per cent
  3. 5 per cent
  4. 6 per cent

Explanation

Synchronous speed is Ns = 120f/p = 120 × 50/6 = 1000 rpm. Slip is (Ns − N)/Ns = (1000 − 960)/1000 = 0.04, that is 4 per cent.