← Junior Engineer
Past Questions
Rainfall occurring when moist air rises over a mountain barrier is known as:
A)
Cyclonic rainfall
B)
Convectional rainfall
C)
Orographic rainfall
D)
Frontal rainfall
The question describes a specific meteorological process where moist air is forced to rise over a physical barrier, such as a mountain range.
1. **Orographic Rainfall (Correct):** The term 'oro' comes from the Greek word for mountain. When moist air encounters a mountain, it is forced to ascend (the windward side). As the air rises, it cools adiabatically, leading to condensation and precipitation. This is the exact process described in the question.
2. **Cyclonic/Frontal Rainfall (Incorrect):** These terms are often used interchangeably. This type of rainfall occurs when two air masses of different temperatures and densities meet (a front), forcing the warmer, lighter air to rise over the colder, denser air.
3. **Convectional Rainfall (Incorrect):** This occurs when the sun heats the ground, which in turn heats the air above it. The warm air becomes less dense and rises vertically in currents, cooling and condensing to form clouds (common in tropical regions).
Therefore, the correct term for rainfall caused by a mountain barrier is Orographic rainfall.
Centrifugal pumps transport fluids by converting:
A)
kinetic energy to hydrodynamic energy
B)
hydrodynamic energy to kinetic energy
C)
mechanical energy to kinetic energy
D)
mechanical energy to hydrodynamic energy
A centrifugal pump operates by using an external power source (such as an electric motor or diesel engine) to rotate an impeller. This rotation provides mechanical energy to the fluid. As the impeller spins, it imparts centrifugal force to the liquid, increasing its velocity (kinetic energy) and pressure (potential energy). The combination of pressure and kinetic energy in a flowing fluid is referred to as hydrodynamic energy. Therefore, the pump converts the mechanical energy of the shaft into hydrodynamic energy of the fluid.
Breakdown of options:
- Option (a) and (b) are incorrect because kinetic energy is a component of hydrodynamic energy, not a separate category to be converted into it in this context.
- Option (c) is partially correct in that mechanical energy becomes kinetic energy, but the ultimate goal of a pump is to create 'head' (pressure), making 'hydrodynamic energy' the more comprehensive and accurate term for the resulting energy state of the fluid.
A spillway is designed for a peak flood discharge of 2000 cumecs. If the velocity of flow over the spillway is 8 m/s and the depth of flow is 2 metres, what is the required width of the spillway?
A)
100 m
B)
125 m
C)
200 m
D)
250 m
To find the required width of the spillway, we use the fundamental Continuity Equation for fluid flow:
Discharge (Q) = Area (A) × Velocity (V)
Given data:
- Peak flood discharge (Q) = 2000 m³/s (cumecs)
- Velocity of flow (V) = 8 m/s
- Depth of flow (d) = 2 m
Step 1: Define the Area (A) of the flow cross-section.
For a rectangular spillway section, Area = Width (B) × Depth (d).
Step 2: Substitute the Area into the discharge formula:
Q = (B × d) × V
Step 3: Rearrange the formula to solve for Width (B):
B = Q / (d × V)
Step 4: Plug in the values:
B = 2000 / (2 × 8)
B = 2000 / 16
B = 125 m
Therefore, the required width of the spillway is 125 metres.
Comparing with the options:
- Option (a) 100 m is incorrect (would result in Q = 1600 cumecs).
- Option (b) 125 m is correct.
- Option (c) 200 m is incorrect (would result in Q = 3200 cumecs).
- Option (d) 250 m is incorrect (would result in Q = 4000 cumecs).
During soil erosion, the deposition occurs when :
A)
Transporting energy is less than resistance energy
B)
Transporting force is dominating the resisting forces
C)
Detachability is high
D)
Detachability is poor
Soil erosion is a three-stage process: detachment, transport, and deposition.
1. Detachment: Occurs when the erosive force (e.g., kinetic energy of raindrops or flowing water) exceeds the soil's cohesive strength (resistance energy).
2. Transport: Occurs when the transporting energy of the medium (water or wind) is sufficient to keep the particles in motion against the forces of gravity and friction.
3. Deposition: Occurs when the transporting energy (velocity/power of the medium) decreases to a point where it is no longer sufficient to overcome the resisting forces (such as gravity, friction, or obstacles).
Therefore, deposition happens specifically when the transporting energy becomes less than the resistance energy, causing the particles to settle out of the medium.
Analysis of other options:
- Option b: If transporting force dominates resisting forces, the soil remains in motion (transport stage) or is further eroded.
- Option c: High detachability leads to more soil being loosened (detachment stage), not deposited.
- Option d: Poor detachability means the soil is resistant to being moved, which prevents erosion from starting but does not trigger the deposition of already transported particles.
Where will the centre of gravity of a uniform rod lie?
A)
At its middle point
B)
At its end
C)
At the centre of its cross-sectional area
D)
Depends upon its material
The centre of gravity (CG) is the point through which the entire weight of a body acts, regardless of its orientation. For a body with a uniform distribution of mass (homogeneous material) and a symmetrical shape, the centre of gravity coincides with its geometric centre (centroid). A 'uniform rod' implies that the mass per unit length is constant throughout its length. For a straight rod of length L, the geometric centre is located at L/2, which is the middle point of the rod.
Why other options are incorrect:
- Option b: The end of the rod is not the balance point; the rod would rotate if supported there.
- Option c: The centre of the cross-sectional area describes the axis of the rod, but not the specific point along the length where the total weight is concentrated.
- Option d: Since the rod is specified as 'uniform', the material is consistent throughout; therefore, the CG depends on the geometry, not the specific type of material used.
To scorn someone means to:
A)
make someone jealous
B)
treat with contempt
C)
make someone feel guilty
D)
talk behind someone’s back
The word 'scorn' is a verb (and noun) that refers to the feeling or expression of open dislike, disdain, or contempt for someone or something that is considered unworthy or inferior.
- Option (b) 'treat with contempt' is the precise definition of scorn.
- Option (a) 'make someone jealous' refers to provoking envy, which is a different emotional dynamic.
- Option (c) 'make someone feel guilty' refers to inducing remorse or shame.
- Option (d) 'talk behind someone’s back' refers to gossip or slander, which may be a result of scorn, but is not the definition of the word itself.
The level at which the water stands in a well before pumping starts, generally expressed as the distance from the ground surface to the water level in the well:
A)
Static water level
B)
Drawdown
C)
Piezometric surface
D)
Pumping water level
Step-by-step reasoning:
1. **Definition of Static Water Level (SWL):** In groundwater hydrology, the static water level is the level at which water stands in a well when there is no pumping occurring (the well is in equilibrium with the surrounding aquifer). It is typically measured as the vertical distance from the ground surface down to the water surface in the well.
2. **Evaluating Option b (Drawdown):** Drawdown is the difference between the static water level and the pumping water level. It represents the drop in water level caused by the extraction of water.
3. **Evaluating Option c (Piezometric surface):** The piezometric surface is an imaginary surface that represents the total head of water in a confined aquifer. While the SWL in a piezometer reflects this surface, the specific term for the level in a well before pumping is the static water level.
4. **Evaluating Option d (Pumping water level):** This is the level to which the water drops in the well while the pump is operating.
Conclusion: Since the question specifies the level 'before pumping starts', the correct term is the Static Water Level.
In a variable displacement pump, as the pumping head increases:
A)
the rate of pumping decreases
B)
the rate of pumping becomes ideal
C)
the rate of pumping increases
D)
Both (a) & (c)
In fluid mechanics and pump theory, the 'pumping head' refers to the total height or pressure the pump must overcome to move the fluid. For any real-world pump, there is an inverse relationship between the head (pressure) and the flow rate (discharge), as described by the pump's characteristic curve (H-Q curve). As the resistance or the required head increases, the pump's ability to move the same volume of fluid per unit of time decreases. In the specific case of a variable displacement pump, while the displacement can be adjusted to compensate for changes, the inherent physical property remains: for a given power input and setting, an increase in the head (back-pressure) leads to a decrease in the actual flow rate due to increased internal slippage (leakage) and the physics of the system's resistance. Therefore, as the pumping head increases, the rate of pumping (discharge) decreases.
The discharge per unit drawdown at a well is known as:
A)
specific yield
B)
specific retention
C)
specific capacity
D)
specific storage
In groundwater hydrology, the 'Specific Capacity' of a pumping well is defined as the discharge (Q) obtained per unit drawdown (s). Mathematically, it is expressed as Specific Capacity = Q/s. It represents the productivity of a well and depends on both the aquifer properties (transmissivity) and the well's construction efficiency.
Why other options are incorrect:
- a. Specific Yield: The ratio of the volume of water that a saturated rock will yield by gravity to the total volume of the rock.
- b. Specific Retention: The ratio of the volume of water a saturated rock retains against gravity to the total volume of the rock.
- d. Specific Storage: The volume of water released from storage per unit volume of aquifer per unit decline in hydraulic head.
A centrifugal pump operates at 1800 rpm and discharges 0.72m3/min of water at 6m head. If the pump operates at 2100 rpm, then the discharge will be:
A)
0.61 m3/min
B)
0.77 m3/min
C)
0.84 m3/min
D)
0.98 m3/min
To solve this problem, we use the Affinity Laws for centrifugal pumps. The Affinity Laws describe the relationship between the speed of the pump (N), the discharge flow rate (Q), and the head (H).
1. **The Affinity Law for Discharge (Q):**
The discharge of a centrifugal pump is directly proportional to the rotational speed of the impeller.
Formula: Q1 / Q2 = N1 / N2
2. **Given Data:**
- Initial speed (N1) = 1800 rpm
- Initial discharge (Q1) = 0.72 m³/min
- Final speed (N2) = 2100 rpm
- Final discharge (Q2) = ?
3. **Calculation:**
Rearranging the formula to solve for Q2:
Q2 = Q1 * (N2 / N1)
Q2 = 0.72 * (2100 / 1800)
Q2 = 0.72 * (7 / 6)
Q2 = 0.12 * 7
Q2 = 0.84 m³/min
4. **Analysis of Options:**
- Option (a) 0.61 m³/min: Incorrect. This would occur if the speed decreased.
- Option (b) 0.77 m³/min: Incorrect calculation.
- Option (c) 0.84 m³/min: Correct. Matches the calculated value based on the Affinity Law.
- Option (d) 0.98 m³/min: Incorrect calculation.
Note: The head (6m) provided in the question is extraneous information for calculating the discharge, although it would change proportionally to the square of the speed (H2 = H1 * (N2/N1)²).
Which chemical compostion has highest content in OPC?
A)
Alumina
B)
Silica
C)
Lime
D)
Iron Oxide
Ordinary Portland Cement (OPC) is manufactured by burning a mixture of calcareous (lime-bearing) and argillaceous (clay-bearing) materials. The chemical composition of OPC typically consists of the following approximate percentages by weight:
1. Lime (CaO): 60% to 67% - This is the primary constituent. It provides strength but too much lime causes unsoundness.
2. Silica (SiO2): 17% to 25% - It imparts strength to the cement.
3. Alumina (Al2O3): 3% to 8% - It acts as a flux, lowering the clinkering temperature.
4. Iron Oxide (Fe2O3): 0.5% to 6% - It gives the characteristic grey color to the cement.
5. Magnesia (MgO), Sulfur Trioxide (SO3), and Alkali oxides: Small percentages.
Comparing the options, Lime has the highest percentage (approx. 63%), followed by Silica, Alumina, and Iron Oxide. Therefore, Lime is the chemical composition with the highest content in OPC.
In which of the following type of surveying only linear measurements are made?
A)
Dumpy level
B)
Chain surveying
C)
Theodolite surveying
D)
Contouring
Step-by-step reasoning: 1. The question asks for a type of surveying where ONLY linear measurements are made. 2. Chain Surveying (also known as Chain and Compass surveying when angles are involved, but pure Chain Surveying relies on triangulation) is the simplest method of surveying where only linear measurements are taken in the field using chains or tapes to determine the positions of points. 3. Dumpy Leveling (Option a) is used primarily for determining vertical distances (elevations) and relative heights. 4. Theodolite Surveying (Option c) involves the measurement of both horizontal and vertical angles, as well as linear distances. 5. Contouring (Option d) is the process of mapping lines of equal elevation, which requires both leveling (vertical) and distance (horizontal) measurements. Therefore, only Chain Surveying fits the criteria of relying solely on linear measurements.
The “Area of Influence” of a well is best defined as:
A)
The total surface area of the well pipe.
B)
The area within which the water table or piezometric surface is lowered by pumping.
C)
The depth of the water-bearing stratum.
D)
The distance from the pump to the discharge point
In groundwater hydrology, when a well is pumped, it creates a depression in the water table (for unconfined aquifers) or the piezometric surface (for confined aquifers) known as a 'cone of depression'. The 'Area of Influence' (or Radius of Influence) refers to the spatial extent around the pumping well where the hydraulic head is affected by the pumping action. Beyond this boundary, the water table remains at its original static level.
Analysis of options:
- Option (a) is incorrect because the surface area of the pipe is a physical dimension of the hardware, not a hydrological zone.
- Option (c) is incorrect because the depth of the stratum refers to the thickness of the aquifer, not the lateral area affected by pumping.
- Option (d) is incorrect because the distance to the discharge point is a matter of plumbing/piping layout and has no relation to the aquifer's hydraulic response.
In LUCC, the suitable lands for cultivation are in:
A)
Class I to IV
B)
Class I to V
C)
Class V to VII
D)
Class I to III
In Land Use Capability Classification (LUCC), land is categorized into eight classes (I through VIII) based on its limitations for cultivation.
1. Classes I to IV are considered 'arable' or suitable for cultivation.
- Class I: Very good land with few limitations.
- Class II: Good land with slight limitations.
- Class III: Moderately good land with moderate limitations.
- Class IV: Fairly good land with severe limitations (often used for limited cultivation or pasture).
2. Classes V to VIII are generally considered 'non-arable' or unsuitable for sustainable cultivation due to severe limitations such as steep slopes, poor drainage, or rocky soil.
- Class V to VII are typically used for grazing, forestry, or wildlife habitats.
- Class VIII is reserved for recreation or wildlife.
Therefore, the range of lands suitable for cultivation is Class I to IV.
What is the maximum percentage of silt allowed in sand to be used in concrete?
A)
5%
B)
10%
C)
8%
D)
2%
In concrete technology, silt refers to the fine particles (usually smaller than 75 microns) present in the sand. Excessive silt is detrimental to concrete because it increases the water demand for a given workability, weakens the bond between the cement paste and the aggregate, and increases the risk of shrinkage and cracking. According to standard specifications (such as IS 383 in the Indian context, which is typically followed in MPSC exams), the maximum permissible limit for silt/clay content in fine aggregates (sand) used for concrete is generally 8% by weight. If the silt content exceeds this limit, the sand must be washed before use to ensure the durability and strength of the concrete structure. Options a, b, and d are incorrect as they do not align with the standard engineering specifications for general concrete production.
A pedometer is most useful for measuring:
A)
Height of a building
B)
Long distances flown
C)
Depth of water
D)
Short walking distances
A pedometer is an electromechanical apparatus that counts the number of steps taken by a person. In surveying, this is used for 'pacing,' where the distance is calculated by multiplying the number of steps by the average length of a single pace.
1. Why 'd' is correct: Pedometers are specifically designed to track steps during walking, making them suitable for estimating short to medium walking distances where high precision is not required (reconnaissance surveys).
2. Why 'a' is incorrect: Height of a building is measured using instruments like theodolites, total stations, or clinometers (trigonometric leveling).
3. Why 'b' is incorrect: Distances flown are measured using GPS, inertial navigation systems, or radar altimeters.
4. Why 'c' is incorrect: Depth of water is measured using sounding leads, echo sounders, or bathymetric sensors.
The most economical section of grass water way is:
A)
Parabolic
B)
Rectangular
C)
Triangular
D)
Trapezoidal
The most economical grass waterway section is the **parabolic** section. For a given cross-sectional area, a parabolic channel provides the least wetted perimeter, which means minimum boundary contact and therefore minimum resistance to flow. This makes it the most hydraulically efficient and economical shape for grassed waterways.
Why the others are incorrect:
- **Rectangular**: has a larger wetted perimeter for the same area, so it is less economical.
- **Trapezoidal**: commonly used in channels, but it is not as efficient as the parabolic section for grass waterways.
- **Triangular**: has even more wetted perimeter relative to area and is generally the least economical among these options.
Hence, the correct answer is **a) Parabolic**.
The relation between Transmissibility (T) and Permeability (K) for an aquifer of depth d, is:
A)
K=Td
B)
T=K.d
C)
T=K. log d
D)
T= ln(Kd)
In groundwater hydrology, Transmissibility (T) is defined as the rate at which water is transmitted through a unit width of an aquifer under a unit hydraulic gradient. It is a measure of the aquifer's capacity to transmit water. Mathematically, Transmissibility is the product of the Hydraulic Conductivity (K), also known as permeability in some contexts, and the saturated thickness or depth (d) of the aquifer. The formula is expressed as T = K × d.
- Option (a) K=Td is incorrect as it suggests permeability is the product of transmissibility and depth.
- Option (c) T=K. log d is incorrect as the relationship is linear, not logarithmic.
- Option (d) T= ln(Kd) is incorrect as it suggests a natural logarithmic relationship, which does not exist for these parameters.
A drop spillway is most suitable when the:
A)
slope is very gentle
B)
discharge is very large
C)
vertical drop is significant
D)
soil is highly permeable
A drop spillway is used where the channel or ground has a sudden, appreciable fall in elevation, i.e., a significant vertical drop. It safely conveys water from a higher to a lower level by allowing the flow to drop over a crest and dissipate energy.
Why the others are incorrect:
- b) Very large discharge: Drop spillways are not chosen primarily because of large discharge; they are more suited to small to moderate flows with a distinct drop.
- a) Very gentle slope: A gentle slope does not require a drop structure; it is not the defining condition for a drop spillway.
- d) Highly permeable soil: Soil permeability is not the criterion for selecting a drop spillway; this relates more to seepage control and foundation considerations, not the need for a drop structure.
The end contraction in a rectangular weir causes:
A)
increase in discharge
B)
decrease in effective length of crest
C)
increase in head
D)
turbulent flow
End contraction in a rectangular weir occurs when the water approaches the crest from the sides and the flow contracts at the ends, reducing the effective width of the crest. Hence, it causes a decrease in the effective length of crest. Option (a) is incorrect because contraction does not increase discharge; it actually reduces discharge for a given head. Option (c) is incorrect because the head is not increased by end contraction; rather, for the same discharge, a greater head may be required due to reduced effective length. Option (d) is incorrect because end contraction is a geometric/flow-width effect, not the direct cause of turbulent flow.
The drilling fluid commonly used in hydraulic rotary drilling is:
A)
Cement slurry
B)
Bentonite mud
C)
Diesel
D)
Lime water
In hydraulic rotary drilling, a drilling fluid (often called 'drilling mud') is circulated through the drill pipe and returned up the annulus. Bentonite, a type of swelling clay, is the most commonly used material for this purpose.
1. Why Bentonite Mud is correct: Bentonite creates a viscous fluid that serves several critical functions: it carries drill cuttings (rock fragments) from the bottom of the hole to the surface; it forms a 'filter cake' on the borehole walls to prevent the fluid from leaking into the surrounding formation and to prevent the walls from collapsing; and it cools and lubricates the drill bit.
2. Why other options are incorrect:
- a. Cement slurry: This is used for 'grouting' or sealing the annulus after the drilling is complete to prevent surface contamination of the aquifer, not as a drilling fluid during the drilling process.
- c. Diesel: While used in some specialized oil drilling operations (oil-based muds), it is not the common fluid for standard groundwater hydrology/water well drilling due to environmental contamination risks.
- d. Lime water: This does not possess the necessary viscosity or thixotropic properties required to transport cuttings or stabilize the borehole walls.
Revised Universal Soil Loss Equation estimates:
A)
Average sediment yield
B)
Average annual sediment yield
C)
Average annual soil erosion
D)
All (a), (b) & (c)
The Revised Universal Soil Loss Equation (RUSLE) is a mathematical model used to predict the long-term average annual rate of soil erosion caused by rainfall and overland flow. The formula is expressed as A = R × K × LS × C × P, where 'A' represents the average annual soil loss per unit area.
1. Why 'c' is correct: RUSLE specifically calculates 'gross erosion' (the total amount of soil detached and transported from a slope), which is defined as the average annual soil erosion.
2. Why 'a' and 'b' are incorrect: There is a critical technical distinction between 'soil erosion' and 'sediment yield'. Soil erosion refers to the detachment and transport of soil from a site, whereas sediment yield refers to the actual amount of sediment that reaches a specific point (like a stream or a reservoir) after accounting for deposition during transport. RUSLE estimates the erosion at the source, not the yield at the outlet. Therefore, it does not estimate sediment yield.
In the designation M15, M refers to the mix and the number refers to:
A)
The specified 28-day cube strength of mix in N/mm2
B)
The specified 28-hours cube strength of mix in N/mm2
C)
The specified days-hours cube strength of mix in N/mm2
D)
The specified 8-hours cube strength of mix in N/mm2
In concrete technology, the designation 'M' stands for 'Mix' and the number following it represents the characteristic compressive strength of the concrete. According to IS 456:2000 (the Indian Standard code for plain and reinforced concrete), the characteristic strength is defined as the strength of a 150mm x 150mm x 150mm cube tested after 28 days of curing. Therefore, in M15, '15' indicates that the specified compressive strength of the concrete cube is 15 N/mm² (or MPa) at 28 days. Options b, c, and d are incorrect because strength is measured in days (specifically 28 days), not hours, to allow for the hydration process of cement to reach a standardized level of maturity.
A centrifugal pump is required to lift water to a total head of 40m at the rate of 50ltr/s. If its overall efficiency is 62%, the power required for the pump will be:
A)
41.6kW
B)
51.6kW
C)
21.6Kw
D)
31.6kW
Discharge, Q = 50 L/s = 0.05 m^3/s.
Hydraulic power required:
P_h = ρgQH = 1000 × 9.81 × 0.05 × 40 = 19,620 W = 19.62 kW.
Overall efficiency, η = 62% = 0.62.
So, input power required:
P = P_h / η = 19.62 / 0.62 = 31.65 kW ≈ 31.6 kW.
Therefore, the correct option is d) 31.6 kW.
Why the others are incorrect:
- a) 41.6 kW: too high; it would correspond to a much lower efficiency or larger head/discharge.
- b) 51.6 kW: far too high for the given flow and head.
- c) 21.6 kW: close to hydraulic power, but ignores the 62% overall efficiency.
Detachment of soil particles is maximum, when the depth of overland flow is between:
A)
1/5 and 1/3 of drop diameter
B)
1/5 and 1/3 of soil’s particle’s diameter
C)
Both (a) & (b)
D)
0.15 to 0.20mm
In the study of soil erosion, specifically rainsplash erosion, the detachment of soil particles is influenced by the interaction between falling raindrops and the existing layer of overland flow (sheet flow). When there is no water on the surface, the raindrop's energy is absorbed directly by the soil. When the water depth is very high, the water acts as a cushion, absorbing the impact energy. Research in soil mechanics and hydrology indicates that the maximum detachment of soil particles occurs when the depth of the overland flow is between 1/5 and 1/3 of the diameter of the falling raindrop. At this specific depth, the impact energy is optimally transmitted to the soil particles to dislodge them, while the flow is sufficient to transport them away, but not deep enough to fully cushion the impact. Option (b) is incorrect because soil particle diameter is far too small to be the governing factor for raindrop impact energy. Option (d) is a specific measurement that does not account for the variability in raindrop sizes.