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Past Questions
When pressure of fluid is measured with respect to atmospheric pressure as datum, it is called
A)
absolute pressure
B)
vacuum pressure
C)
gauge pressure
D)
all the above
In fluid mechanics, pressure is measured relative to a specific reference point or datum.
1. **Gauge Pressure**: This is the pressure measured relative to the local atmospheric pressure. If the fluid pressure is higher than atmospheric pressure, the gauge pressure is positive. If it is lower, it is often referred to as vacuum pressure. The formula is: Gauge Pressure = Absolute Pressure - Atmospheric Pressure.
2. **Absolute Pressure**: This is the pressure measured relative to a perfect vacuum (zero pressure). It is the sum of the gauge pressure and the atmospheric pressure. The formula is: Absolute Pressure = Gauge Pressure + Atmospheric Pressure.
3. **Vacuum Pressure**: This is a specific type of gauge pressure that occurs when the pressure is below atmospheric pressure. It is measured as the difference between atmospheric pressure and the absolute pressure.
Since the question specifically asks for the term used when atmospheric pressure is used as the datum, the correct term is 'gauge pressure'.
When canal bed level is higher than the natural drainage, then the canal is carried over a natural drainage. Such cross drainage work is called
A)
aqueduct
B)
super passage
C)
siphon
D)
level crossing
In irrigation engineering, cross drainage works are constructed when a canal intersects a natural drainage (like a river or stream). The type of structure depends on the relative levels of the canal bed and the drainage bed:
1. **Aqueduct**: This is used when the canal bed level is higher than the High Flood Level (HFL) of the natural drainage. The canal is carried over the drainage in a trough or trough-like structure, and the drainage flows freely underneath. This matches the condition described in the question.
2. **Super Passage**: This is the opposite of an aqueduct. It is used when the natural drainage is carried over the canal. Here, the canal bed is lower than the drainage bed.
3. **Siphon Aqueduct**: This is used when the canal is carried over the drainage, but the drainage water level is higher than the canal bed, forcing the drainage water to flow under pressure through a siphon.
4. **Level Crossing**: This is used when the canal and the drainage intersect at nearly the same level, and both are allowed to flow under pressure through the structure.
Since the question specifies that the canal bed level is higher and the canal is carried over the natural drainage, the correct structure is an aqueduct.
When the canal and the drainage meet each other at the same level and quality of water of both is almost the same, cross drainage work constructed is
A)
super passage
B)
siphon
C)
level crossing
D)
aqueduct
In irrigation engineering, cross drainage works are constructed when a canal crosses a natural drain. The choice of structure depends on the relative levels of the canal and the drain, and the quality of water.
1. **Level Crossing**: This is used when the canal and the drainage meet at the same level and the water quality of both is similar. In this structure, the canal and the drain are allowed to mix.
2. **Aqueduct**: Used when the canal is carried over the drain via a trough, and the canal bed is higher than the high flood level (HFL) of the drain. There is no mixing of water.
3. **Siphon Aqueduct**: Similar to an aqueduct, but the drain is carried under the canal through a siphon because the HFL of the drain is higher than the canal bed.
4. **Super Passage**: Used when the drain is carried over the canal. The canal is carried under the drain.
5. **Siphon**: Generally refers to a structure where water is carried under pressure through a dipped pipe or conduit.
Since the question specifies that the levels are the same and the water quality is almost the same, a 'level crossing' is the most appropriate and economical choice.
Performance of turbine under unit head is expressed in
A)
unit speed (Nu)
B)
unit power (Pu)
C)
unit discharge (Qu)
D)
all the above
In hydraulic turbine analysis, 'unit quantities' are non-dimensional or normalized parameters used to describe the performance of a turbine regardless of the actual head (H) available. This allows engineers to compare turbines of different sizes.
1. Unit Speed (Nu): Defined as the speed of the turbine divided by the square root of the head (Nu = N / √H). It represents the performance in terms of rotational speed under unit head.
2. Unit Discharge (Qu): Defined as the actual discharge divided by the head raised to the power of 3/2 (Qu = Q / H^(3/2)). It represents the volume of water passing through the turbine under unit head.
3. Unit Power (Pu): Defined as the actual power developed divided by the head raised to the power of 5/2 (Pu = P / H^(5/2)). It represents the power output under unit head.
Since all three parameters (speed, discharge, and power) are expressed as 'unit' values to describe turbine performance under a unit head, the correct answer is 'all the above'.
The road pavement shown in the paper is called
A)
Flexible pavement
B)
Rigid pavement
C)
Semi rigid pavement
D)
Composite pavement
Duplicate of above - typical pavement diagram is flexible pavement.
Remote sensing is the science of making inferences about objects from measurements, made at a distance, without coming into physical contact with the object under study, may be of the following types
A)
active remote sensing
B)
passive remote sensing
C)
both (a) and (b)
D)
none of the above
Remote sensing is broadly classified into two main categories based on the source of the energy used to detect the object:
1. **Passive Remote Sensing**: These sensors detect natural radiation (usually sunlight) that is reflected or emitted by the object. For example, traditional photography and thermal imaging are passive because they rely on existing energy sources.
2. **Active Remote Sensing**: These sensors provide their own source of energy. The sensor emits a signal toward the target and then measures the reflection or backscatter of that signal. Examples include RADAR (Radio Detection and Ranging) and LiDAR (Light Detection and Ranging).
Since both active and passive methods are fundamental types of remote sensing, option (c) is the correct choice.
For night landing, the thresholds are lighted
A)
white
B)
yellow
C)
green
D)
red
In airport lighting systems, specific colors are used to guide pilots during night landings or low-visibility conditions. The runway threshold lights are designed to mark the beginning of the runway available for landing. According to international aviation standards (ICAO and FAA), threshold lights are green. These lights indicate the start of the landing surface to the approaching pilot. In contrast, the runway end lights (which mark the end of the runway for a landing aircraft or the start for a departing aircraft) are red. White lights are typically used for the runway edge lights to define the lateral limits of the runway. Yellow lights are commonly used for taxiway centerlines or runway guard lights. Therefore, for night landing, the threshold lights are green.
Pressure rise within the pipe due to water hammer depends on
A)
velocity of flow
B)
time of valve closure
C)
elastic properties of fluid and pipe materials
D)
all the above
Water hammer Δp = rho*a*Vo depends on flow velocity, closure time, and elasticity of fluid and pipe, so all factors.
In laminar boundary layer, thickness of boundary layer δ varies with longitudinal distance x from leading edge as
A)
x-1/2
B)
x1/2
C)
x
D)
x2
In fluid mechanics, specifically for a laminar boundary layer over a flat plate, the growth of the boundary layer thickness (δ) is governed by the Blasius solution. The boundary layer thickness is defined as the distance from the wall where the velocity reaches 99% of the free-stream velocity (U∞). The formula for the boundary layer thickness in laminar flow is given by: δ ≈ 5 * x / sqrt(Re_x), where Re_x is the Reynolds number at distance x. Since Re_x = (ρ * U∞ * x) / μ, we can substitute this into the equation: δ ∝ x / sqrt(x) = x^(1 - 1/2) = x^(1/2). Therefore, the thickness of the laminar boundary layer varies with the square root of the longitudinal distance x from the leading edge. Option (a) is incorrect as it suggests an inverse relationship; option (c) suggests a linear relationship (which occurs in some specific non-Newtonian or different flow regimes); and option (d) suggests a quadratic relationship, which is physically incorrect for this scenario.
Practical use of Bernoulli’s equation is applied to
A)
venturimeter
B)
orifice meter
C)
nozzle meter
D)
all the above
Bernoulli's equation states that for an incompressible, non-viscous fluid in steady flow, the sum of pressure energy, kinetic energy, and potential energy per unit volume remains constant along a streamline. This principle is the fundamental basis for flow measurement devices that create a pressure drop to determine flow velocity.
1. Venturimeter: It uses a converging section to increase velocity and decrease pressure. The pressure difference between the inlet and the throat is measured and used to calculate the flow rate based on Bernoulli's principle.
2. Orifice meter: Similar to the venturimeter, it creates a constriction (orifice plate) that causes a pressure drop. The relationship between the pressure difference and the flow rate is derived from Bernoulli's equation (with a discharge coefficient to account for losses).
3. Nozzle meter: This device uses a converging section (nozzle) to accelerate the fluid, creating a pressure drop that is measured to determine the flow rate, again applying the principles of Bernoulli's equation.
Since all three devices rely on the conversion of pressure energy into kinetic energy to measure flow rate, they are all practical applications of Bernoulli's equation.
Falling drops of water becomes sphere due to
A)
adhesion
B)
cohesion
C)
surface tension
D)
viscosity
The phenomenon where falling drops of water assume a spherical shape is primarily due to surface tension. Surface tension is the property of a liquid surface that causes it to behave like a stretched elastic membrane. This occurs because molecules at the surface experience a net inward cohesive force, pulling them toward the bulk of the liquid. Mathematically, for a given volume, a sphere has the minimum surface area. To minimize the total surface energy (potential energy), the liquid naturally assumes a spherical shape.
Why other options are incorrect:
- Adhesion: This is the attraction between molecules of different substances (e.g., water and glass). It does not cause a drop to form a sphere in mid-air.
- Cohesion: While surface tension is caused by cohesive forces between similar molecules, 'surface tension' is the specific physical property/effect that results in the minimization of surface area and the formation of a sphere.
- Viscosity: This is the internal friction or resistance of a fluid to flow. While it affects the rate at which a drop falls or deforms, it does not drive the shape toward a sphere.
Lacey’s regime equation of velocity for calculating flood discharge in river is
A)
V = 10.8R2/3S1/3
B)
V = 10.8R1/2S1/2
C)
V = 10.8R1/3S2/3
D)
V = 10.8R2/3S1/3 (duplicate)
Lacey's Regime Theory is used to determine the characteristics of a river channel in alluvium. According to Lacey, the average velocity (V) of flow in a regime channel is proportional to the hydraulic radius (R) raised to the power of 2/3 and the bed slope (S) raised to the power of 1/3. The empirical formula is expressed as: V = 10.8 R^(2/3) S^(1/3) (where V is in m/s, R is the hydraulic radius in meters, and S is the bed slope).
Comparing this to the options:
- Option (a) matches the formula V = 10.8 R^(2/3) S^(1/3).
- Option (b) suggests V = 10.8 R^(1/2) S^(1/2), which is incorrect.
- Option (c) suggests V = 10.8 R^(1/3) S^(2/3), which is incorrect.
- Option (d) is a duplicate of option (a).
Contour lines overlap in
A)
vertical cliff
B)
steep slope
C)
hill
D)
all (a), (b) and (c)
In contour mapping, contour lines are imaginary lines joining points of equal elevation. The spacing and behavior of these lines indicate the nature of the terrain:
1. **Vertical Cliff**: When a terrain is perfectly vertical, multiple elevation points exist at the same horizontal location. Therefore, the contour lines for different elevations will appear to merge or overlap at that specific point on the map.
2. **Steep Slope**: On a steep slope, contour lines are drawn very close to each other, but they remain distinct and do not overlap.
3. **Hill**: A hill is represented by closed concentric loops. While the lines are close together on the sides, they do not overlap.
4. **Overhanging Cliff**: It is worth noting that if a cliff overhangs, the contour lines actually cross each other, but for a standard vertical cliff, they overlap.
According to Railway Board, diamond crossing should be flatter than
A)
1 in 16
B)
1 in 12
C)
1 in 8.5
D)
1 in 6
In railway engineering, a diamond crossing is a configuration where two tracks cross each other at grade. The 'flatness' of the crossing refers to the angle of the crossing. According to the Indian Railway Board standards, to ensure safety, reduce wear and tear on the rails, and prevent derailments caused by excessive lateral forces, diamond crossings should be flatter than 1 in 8.5. A 'flatter' crossing means a larger ratio (e.g., 1 in 10 is flatter than 1 in 8.5), meaning the angle of intersection is smaller. If the crossing is steeper than 1 in 8.5 (e.g., 1 in 6), the impact forces on the wheel flanges and the rail head increase significantly, leading to rapid deterioration of the track and increased risk of accidents. Therefore, 1 in 8.5 is the standard minimum flatness requirement.
Precipitation that occurs due to conflict between two air masses is called
A)
frontal precipitation
B)
convective precipitation
C)
orographic precipitation
D)
cyclonic precipitation
Precipitation is classified based on the mechanism that causes the air to rise and cool.
1. **Frontal Precipitation (Correct):** This occurs when two air masses of different temperatures and densities (e.g., a warm moist air mass and a cold dry air mass) meet. The warmer, lighter air is forced to rise over the colder, denser air. As the warm air rises, it cools adiabatically, leading to condensation and precipitation. This 'conflict' zone is known as a front.
2. **Convective Precipitation:** This occurs when the sun heats the ground, which in turn heats the air immediately above it. This warm air becomes buoyant and rises vertically in currents, leading to localized, often intense rainfall (common in tropical regions).
3. **Orographic Precipitation:** This occurs when moist air is physically forced to rise over a topographic barrier, such as a mountain range. The air cools as it ascends the windward side, resulting in precipitation.
4. **Cyclonic Precipitation:** While frontal precipitation is a type of cyclonic precipitation (occurring in extratropical cyclones), 'frontal' specifically describes the 'conflict between two air masses' mentioned in the question. Cyclonic precipitation is a broader term referring to precipitation associated with low-pressure systems.
Capacity of reservoir is usually determined by
A)
mass curve of rainfall
B)
mass curve of inflow
C)
depth-area duration curve
D)
intensity duration frequency curve
The capacity of a reservoir is determined based on the need to store excess water during periods of high inflow and release it during periods of low inflow to meet a specific demand. The 'Mass Curve of Inflow' (also known as the cumulative inflow curve) is a plot of the cumulative volume of water entering the reservoir over time. By plotting the cumulative demand (cumulative outflow) against the cumulative inflow, the maximum difference between the two curves represents the required storage capacity of the reservoir to ensure that the demand is met even during the driest periods.
Why other options are incorrect:
- (a) Mass curve of rainfall: Rainfall is a component of inflow, but reservoir capacity is based on the actual water reaching the reservoir (inflow), which accounts for runoff coefficients and losses.
- (c) Depth-area duration curve: This is used to determine the relationship between the depth of water in a reservoir and the surface area, which helps in calculating the storage volume for a given depth, but it does not determine the required capacity based on demand.
- (d) Intensity duration frequency (IDF) curve: This is used in urban drainage and storm sewer design to relate rainfall intensity, duration, and return period, not for reservoir storage capacity.
River training works are necessary to
A)
direct the river flow in a desired path
B)
minimize the problems of flood and erosion
C)
control meandering and deposition
D)
all the above
River training works refer to various engineering measures adopted to control and guide the flow of a river.
1. **Directing the river flow (Option a):** Structures like guides banks and spurs are used to ensure the river follows a specific channel path, preventing it from shifting away from bridges or critical infrastructure.
2. **Minimizing flood and erosion (Option b):** By stabilizing the banks (using rip-rap or revetments) and managing the flow velocity, river training works reduce the risk of bank erosion and help manage floodwaters more effectively.
3. **Controlling meandering and deposition (Option c):** Rivers naturally tend to meander (curve) and deposit sediment in certain areas, which can lead to channel blockage or unpredictable course changes. Training works help maintain a stable channel alignment and prevent excessive siltation in critical areas.
Since all three objectives are primary goals of river training, the correct answer is 'all the above'.
Global Positioning System (GPS) has become widely used aid to
A)
navigation world wide and a useful tool for map making
B)
land surveying, off shore drilling
C)
pipe and power line survey
D)
navigation to civilian ships and air crafts
E)
all the above
The Global Positioning System (GPS) is a satellite-based radionavigation system that provides geolocation and time information to a GPS receiver anywhere on Earth. Its versatility allows it to be used across various sectors:
1. Navigation and Mapping (Option a): GPS is the primary tool for worldwide navigation and is essential for creating accurate digital and physical maps (GIS).
2. Land Surveying and Offshore Drilling (Option b): In civil engineering and geology, GPS (specifically DGPS or RTK) is used for high-precision land surveying and determining the exact coordinates for offshore oil and gas drilling rigs.
3. Infrastructure Surveying (Option c): GPS is used to map the trajectories of underground pipes and overhead power lines to ensure accurate maintenance and installation.
4. Aviation and Maritime (Option d): Civilian ships and aircraft rely on GPS for route planning, positioning, and safety to avoid collisions and navigate open waters/skies.
Since GPS is fundamentally used in all the scenarios listed in options a, b, c, and d, the correct answer is 'all the above'.
Remote sensing is the science of making inferences about objects from measurements, made at a distance, without coming into physical contact with the object under study, may be of the following types
A)
active remote sensing
B)
passive remote sensing
C)
both (a) and (b)
D)
none of the above
Remote sensing is categorized into two primary types based on the source of the energy used to detect the object:
1. **Passive Remote Sensing**: These sensors detect natural radiation that is emitted or reflected by the object or surrounding areas. The most common source of radiation is sunlight. Examples include traditional photography, radiometers, and multispectral scanners.
2. **Active Remote Sensing**: These sensors provide their own source of energy for illumination. The sensor emits radiation toward the target and then measures the radiation that is reflected back. Examples include RADAR (Radio Detection and Ranging) and LiDAR (Light Detection and Ranging).
Since remote sensing encompasses both the use of naturally occurring energy (passive) and artificially generated energy (active), the correct answer is both (a) and (b).
Main causes of water logging are
A)
excessive rainfall
B)
inadequate surface drainage
C)
low permeability of soil
D)
all the above
Water logging occurs when the soil becomes saturated with water, causing the water table to rise to a level where it restricts the aeration of plant roots. This can be caused by several factors:
1. **Excessive Rainfall (Option a):** When the amount of precipitation exceeds the soil's infiltration capacity and the rate of evaporation/transpiration, water accumulates on the surface and in the root zone.
2. **Inadequate Surface Drainage (Option b):** If the land is poorly graded or lacks proper drainage channels, water cannot flow away from the fields, leading to stagnation and saturation of the soil profile.
3. **Low Permeability of Soil (Option c):** Soils with high clay content (low hydraulic conductivity) prevent water from percolating downward into deeper aquifers, causing water to remain trapped in the upper soil layers.
Since all three factors contribute significantly to the occurrence of water logging, the correct answer is 'all the above'.
California Bearing Ratio method of designing flexible pavements is more accurate as it involves
A)
character of the road making materials
B)
characteristics of soil
C)
traffic intensities
D)
none of the above
The California Bearing Ratio (CBR) test is a penetration test used to evaluate the mechanical strength of road subgrades and base course materials. The primary purpose of the CBR method in flexible pavement design is to determine the thickness of the pavement layers required to support a specific load without causing excessive deformation in the underlying soil.
1. Why 'characteristics of soil' is correct: The CBR value is a direct measure of the shear strength and bearing capacity of the subgrade soil. By quantifying how much load the soil can sustain (relative to a standard crushed stone), engineers can design a pavement thickness that distributes the traffic load effectively to avoid soil failure.
2. Why 'character of the road making materials' is incorrect: While CBR can be performed on base/sub-base materials, the 'method of designing' specifically relies on the subgrade's bearing capacity as the critical limiting factor.
3. Why 'traffic intensities' is incorrect: Traffic intensity (expressed as Cumulative Standard Axles or MSA) is a separate input used in conjunction with the CBR value to determine the total thickness, but the CBR test itself does not 'involve' or measure traffic; it measures the soil's physical properties.
In pipe flow, shear velocity V* is related to friction factor f and average velocity V as
A)
V* = V sqrt(f/8)
B)
V* = V sqrt(f/4)
C)
V* = V sqrt(f/1)
D)
V* = V sqrt(f/2)
1. Definition of Shear Velocity (u* or V*): Shear velocity is defined as the velocity scale associated with the wall shear stress (τ₀) in a pipe flow. The formula is: V* = sqrt(τ₀ / ρ), where τ₀ is the wall shear stress and ρ is the fluid density.
2. Relation to Pressure Drop: For a pipe of diameter D and length L, the wall shear stress is related to the pressure drop (ΔP) by the force balance: τ₀ = (ΔP * D) / (4L).
3. Relation to Friction Factor (f): According to the Darcy-Weisbach equation, the pressure drop is given by ΔP = f * (L/D) * (ρV²/2).
4. Substituting ΔP into the shear stress equation:
τ₀ = [(f * (L/D) * (ρV²/2)) * D] / (4L)
τ₀ = (f * ρV²) / 8
5. Substituting τ₀ back into the shear velocity formula:
V* = sqrt((f * ρV²) / (8 * ρ))
V* = sqrt(fV²/8)
V* = V * sqrt(f/8)
Therefore, the shear velocity V* is equal to the average velocity V multiplied by the square root of (f/8). Option (a) is the correct mathematical derivation.
The earthen embankments constructed parallel to the river banks at suitable distance for flood control are called
A)
flood walls
B)
dikes
C)
levees
D)
both (b) and (c)
Step-by-step reasoning: 1. The question asks for the term used for earthen embankments built parallel to river banks to prevent flooding. 2. Levees are defined as embankments built along the banks of a river to prevent the water from overflowing into the surrounding floodplains. 3. Dikes are similar structures; while often used to reclaim land from the sea or protect low-lying land from flooding, in many hydrological and civil engineering contexts, the terms 'levee' and 'dike' are used interchangeably to describe flood-control embankments. 4. Flood walls (Option a) are different because they are typically vertical structures made of concrete or masonry, not 'earthen embankments'. Therefore, since both levees and dikes refer to earthen embankments used for flood control, option (d) is the most comprehensive and correct answer.
If a spur is constructed at about 60º to 80º inclined upstream, it is called
A)
attracting spur
B)
deflecting spur
C)
repelling spur
D)
permeable spur
In river engineering, spurs (or groynes) are structures constructed from the river bank into the channel to protect the bank from erosion or to redirect the flow. They are classified based on the angle they make with the river bank:
1. **Attracting Spur**: These are inclined downstream (usually 60° to 80° to the bank). They attract the flow towards the bank where the spur is located, which can lead to erosion at the nose of the spur and potentially the bank itself.
2. **Repelling Spur**: These are inclined upstream (usually 60° to 80° to the bank). They deflect the current away from the bank and towards the center of the channel, thereby protecting the bank from erosion. This is the specific case described in the question.
3. **Deflecting Spur**: These are generally constructed perpendicular to the bank (90°). They are used to deflect the flow in a specific direction.
4. **Permeable Spur**: This refers to the material construction (e.g., timber piles) rather than the angle of inclination. Permeable spurs allow some water to pass through, reducing the turbulence at the nose.
Since the question specifies a spur inclined upstream at 60º to 80º, it is a repelling spur.
A well conditioned triangle in a triangulation system is
A)
an isosceles triangle of base angles of 56º14'
B)
an isosceles triangle of base angles of 66º14'
C)
an isosceles triangle of base angles of 76º14'
D)
none of the above
Best well-conditioned triangle has angles as close to 60° as possible, standard is isosceles with base angles 56°14'.