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Past Questions — 2010
The intensity of pressure developed by surface tension (σ) of 0.073575N/m in a droplet of 0.075mm diameter is
A)
39.24 N/m2
B)
392.4 N/m2
C)
3924 N/m2
D)
39240 N/m2
To find the intensity of pressure developed by surface tension in a droplet, we use the formula for the internal pressure of a liquid droplet:
Pressure (P) = 4σ / d
Where:
σ = Surface tension = 0.073575 N/m
d = Diameter of the droplet = 0.075 mm = 0.075 × 10⁻³ m = 0.000075 m
Step-by-step calculation:
1. Substitute the values into the formula: P = (4 × 0.073575) / 0.000075
2. Calculate the numerator: 4 × 0.073575 = 0.2943
3. Divide by the diameter: 0.2943 / 0.000075 = 3924 N/m²
Comparing this result to the given options:
- Option a (39.24 N/m²) is off by a factor of 100.
- Option b (392.4 N/m²) is off by a factor of 10.
- Option c (3924 N/m²) matches our calculated result exactly.
- Option d (39240 N/m²) is off by a factor of 10.
Therefore, the correct intensity of pressure is 3924 N/m².
For general engineering purposes, soils are classified as
A)
particle size system
B)
textural system
C)
High Way Research Board system
D)
unified soil classification system
In geotechnical and civil engineering, soils are classified based on their engineering properties to predict their behavior under load.
1. **Unified Soil Classification System (USCS):** This is the most widely used system for general engineering purposes. It classifies soils into categories such as gravels (G), sands (S), silts (M), and clays (C) based on grain size distribution and plasticity (Atterberg limits). It is designed specifically for engineers to communicate soil types consistently across projects.
2. **Textural System (Option b):** This is primarily used in agriculture and soil science to describe the proportion of sand, silt, and clay. It does not account for plasticity or engineering behavior.
3. **High Way Research Board (HRB) / AASHTO System (Option c):** While used in engineering, this system is specifically tailored for highway construction and pavement design, rather than 'general engineering purposes'.
4. **Particle Size System (Option a):** This is a component of classification (sieve analysis), but it is not a comprehensive classification 'system' on its own, as it ignores the chemical and plastic properties of fine-grained soils.
Different electronic distance measurement (EDM) instruments are
A)
Tellurometer
B)
Geodimeter
C)
Distameter
D)
Electro-optical Distance Meter
E)
all the above
Electronic Distance Measurement (EDM) refers to a variety of instruments used to determine the distance between two points using electromagnetic waves (infrared, light, or microwaves).
1. **Tellurometer**: One of the earliest EDM instruments, it uses microwave signals to measure distance.
2. **Geodimeter**: This instrument uses modulated light beams (visible light) and measures the phase shift to determine distance.
3. **Distameter**: A general term often used for distance-measuring devices, including specific commercial EDM brands and types that utilize light or laser pulses.
4. **Electro-optical Distance Meter**: A broad category of EDM that uses the properties of light (optical) and electronics to calculate distance, typically through time-of-flight or phase-comparison methods.
Since all the listed instruments are types of EDM technology, the correct option is 'all the above'.
φ-index, W-index, f index are some indices to measure
A)
rainfall
B)
infiltration
C)
evaporation
D)
transpiration
phi, W, and f indices measure rate of infiltration loss.
The spans are considered approximately equal if the longest span does not exceed the shortest span by more than
A)
15%
B)
10%
C)
20%
D)
5%
In the design of steel structures, particularly when designing trusses or frames for multiple spans, engineers often simplify calculations by assuming spans are equal if the variation between them is minimal. According to standard structural engineering practice and design manuals (often referenced in textbooks for steel design), spans are considered approximately equal if the longest span does not exceed the shortest span by more than 10%. This allows for the standardization of members and simplifies the analysis of load distribution across the structure without introducing significant errors in the structural integrity or safety margins. Options a (15%), c (20%), and d (5%) are incorrect as they do not align with this specific industry convention for 'approximately equal' spans in this context.
Equipments for compaction are used for
A)
rolling
B)
kneading
C)
vibrations
D)
All the above
Compaction is the process of increasing the density of soil by packing the particles closer together and expelling air. Different types of soil require different mechanisms for effective compaction:
1. **Rolling (Static Pressure):** Used primarily for granular soils and subgrades. Smooth wheel rollers apply static pressure to compress the soil.
2. **Kneading (Pressure + Displacement):** Used primarily for cohesive soils (like clay). Sheep-foot rollers apply a kneading action that compresses the soil from the bottom up by displacing particles.
3. **Vibrations (Dynamic Force):** Used primarily for cohesionless soils (like sand). Vibratory rollers use high-frequency vibrations to rearrange particles into a denser configuration.
Since compaction equipment is designed to utilize all these mechanisms depending on the soil type, the correct answer is 'All the above'.
A foundation rests on
A)
base of the foundation
B)
sub grade
C)
foundation soil
D)
both (b) and (c)
In foundation engineering, a foundation is the lower part of a structure that transmits the load of the superstructure to the underlying soil or rock.
1. **Foundation Soil**: This is the general term for the soil layer that directly supports the foundation and resists the applied loads. Therefore, a foundation rests on the foundation soil.
2. **Subgrade**: The subgrade refers to the native soil prepared and compacted to support any superimposed layers (like a foundation or a pavement). In the context of structural foundations, the subgrade is the actual ground surface upon which the foundation is placed.
3. **Base of the foundation**: This is the bottom surface of the concrete/masonry structure itself. A foundation does not 'rest on' its own base; rather, its base rests on the soil.
Since both 'subgrade' and 'foundation soil' describe the supporting medium upon which the foundation is placed, option (d) is the most comprehensive and correct answer.
In angle dozer, blades are attached to the front side of the tractor usually at an angle of
A)
90º
B)
60º
C)
30º
D)
180º
A standard bulldozer blade is typically mounted perpendicular (90°) to the line of travel for straight pushing. However, an 'angle dozer' is specifically designed with a blade that can be pivoted to the side. This allows the operator to push material laterally (sideways) away from the path of the tractor, which is essential for grading, spreading, and windrowing. In construction equipment standards, the typical maximum angle for an angle dozer blade is approximately 30 degrees relative to the perpendicular (or shifted by 30 degrees from the center line) to optimize the balance between pushing force and the ability to cast material to the side.
- Option (a) 90º refers to a straight blade, not an angle blade.
- Option (b) 60º is too steep and would cause the material to slide off too quickly or put excessive lateral stress on the tractor chassis.
- Option (d) 180º would mean the blade is facing backward, which is functionally impossible for a dozer.
M 20 grade concrete means its compressive strength of 15 cm cube is 30 N/mm2 after
A)
7 days
B)
14 days
C)
21 days
D)
28 days
1. Understanding Concrete Grade Notation: In the designation 'M 20', 'M' stands for the Mix and '20' represents the characteristic compressive strength of a 150 mm (15 cm) cube of concrete in N/mm² (MPa).
2. Standard Curing Period: According to IS 456:2000 (the Indian Standard code for Plain and Reinforced Concrete), the characteristic strength of concrete is defined as the strength of a cube specimen tested after a standard curing period of 28 days.
3. Analysis of the Question: The question mentions 'M 20 grade concrete' but then states a strength of '30 N/mm²'. This is a technical discrepancy in the question's phrasing because M 20 should have a strength of 20 N/mm². However, regardless of whether the strength is 20 or 30 N/mm², the standard time interval for determining the 'grade' or 'characteristic strength' of concrete is always 28 days.
4. Evaluating Options:
- 7 days: Concrete typically achieves about 65-70% of its strength.
- 14 days: Concrete achieves a higher percentage, but it is not the standard for grading.
- 21 days: Not a standard benchmark for characteristic strength.
- 28 days: The globally and nationally accepted standard for testing the characteristic compressive strength of concrete.
A compression member consisting of angle sections may be
A)
continuous member
B)
discontinuous single angle strut
C)
discontinuous double angle strut
D)
all the above
In steel structure design, compression members (struts) can be configured in several ways depending on the structural requirements and the type of truss or frame being constructed.
1. **Continuous Members**: A compression member can be a single continuous piece of steel (such as a long angle or a built-up section) that spans across multiple nodes of a truss.
2. **Discontinuous Single Angle Struts**: In many truss designs, a single angle section is used as a strut. It is termed 'discontinuous' if it is spliced or connected at intervals rather than being one single piece from end to end, or if it is used as a short bracing member between main chords.
3. **Discontinuous Double Angle Struts**: For higher load capacities and to reduce eccentricity (which causes bending moments in compression members), two angle sections are often used back-to-back. These can also be discontinuous or spliced.
Since all three configurations (continuous, discontinuous single, and discontinuous double angles) are valid and commonly used engineering practices for compression members, the correct answer is 'all the above'.
The energy stored in beam of length L, subjected to a constant bending moment M is
A)
M2L / 2EI
B)
ML2 / 2EI
C)
M2L / EI
D)
ML2 / EI
The strain energy stored in a beam due to bending is given by the general formula: U = ∫ (M² / 2EI) dx, where M is the bending moment, E is the Young's modulus, I is the moment of inertia, and x is the length along the beam. In this specific problem, the bending moment M is constant over the entire length L of the beam. Therefore, the integration becomes: U = (M² / 2EI) ∫ dx from 0 to L. Evaluating the integral gives U = (M² / 2EI) * [x] from 0 to L = (M²L) / 2EI. Note: In the provided options, 'M2L' is a typographical representation of M²L. Option (a) matches this derived formula. Options (b), (c), and (d) are incorrect because they either miss the square on the moment M or omit the factor of 1/2 required by the strain energy formula.
The Indian Standard (IS) code which deals with steel structures is
A)
IS: 875
B)
IS: 456
C)
IS: 800
D)
IS: 1893
The correct answer is IS: 800. Here is the detailed breakdown of the options provided:
1. **IS 800 (Correct):** This is the primary Indian Standard code for the 'General Construction in Steel'. It provides the guidelines, design criteria, and specifications for the design of structural steelwork.
2. **IS 875 (Incorrect):** This code deals with the 'Code of Practice for Design Loads (for Buildings and Structures)'. It is divided into several parts (Part 1: Dead Loads, Part 2: Imposed Loads, Part 3: Wind Loads, etc.) and is used for all types of structures, not just steel.
3. **IS 456 (Incorrect):** This is the 'Plain and Reinforced Concrete - Code of Practice'. It is the fundamental code used for the design and construction of concrete structures.
4. **IS 1893 (Incorrect):** This code deals with the 'Criteria for Earthquake Resistant Design of Structures'. It provides guidelines for seismic analysis and design for various types of buildings and structures.
Moment of inertia of a triangular section with base b and height h about centroidal axis parallel to the base is
A)
bh3/3
B)
bh3/8
C)
bh3/12
D)
bh3/36
Step-by-step derivation:
1. Moment of Inertia about the base axis (I_base): For a triangle with base 'b' and height 'h', the moment of inertia about the axis passing through the base is given by the formula I_base = (bh³)/12.
2. Position of Centroid: The centroid of a triangle is located at a distance of h/3 from the base.
3. Parallel Axis Theorem: The theorem states that I_base = I_centroid + A*d², where 'A' is the area of the section and 'd' is the distance between the two parallel axes.
4. Calculation:
- Area (A) = (1/2)bh
- Distance (d) = h/3
- I_centroid = I_base - A*d²
- I_centroid = (bh³/12) - [(1/2)bh * (h/3)²]
- I_centroid = (bh³/12) - [(1/2)bh * (h²/9)]
- I_centroid = (bh³/12) - (bh³/18)
- To subtract, find a common denominator (36): (3bh³ - 2bh³) / 36 = bh³/36.
Therefore, the moment of inertia about the centroidal axis parallel to the base is bh³/36. Option (a) is incorrect, (b) is incorrect, and (c) represents the moment of inertia about the base axis, not the centroidal axis.
The maximum shear stress in a rectangular beam is
A)
2 times the average
B)
1.75 times the average
C)
1.5 times the average
D)
1.25 times the average
In a rectangular beam subjected to a transverse shear force, the shear stress is not distributed uniformly across the cross-section. It follows a parabolic distribution, where the shear stress is zero at the top and bottom edges and reaches its maximum value at the neutral axis (the center of the beam).
1. **Average Shear Stress (τ_avg):** This is calculated as the total shear force (V) divided by the cross-sectional area (A = b * d).
τ_avg = V / (b * d)
2. **Maximum Shear Stress (τ_max):** For a rectangular section, the formula for shear stress at any point is τ = (V * Q) / (I * b), where Q is the first moment of area and I is the moment of inertia. At the neutral axis (the maximum point):
τ_max = (3/2) * (V / (b * d))
3. **Relationship:** Comparing the two formulas:
τ_max = 1.5 * τ_avg
Therefore, the maximum shear stress in a rectangular beam is 1.5 times the average shear stress. Options a, b, and d are incorrect as they do not align with the derived mechanical property of rectangular sections.
In limit state method, the design bond stress of M 30 grade concrete for plain bars in tension is
A)
1.0 N/mm2
B)
1.2 N/mm2
C)
1.4 N/mm2
D)
1.5 N/mm2
According to IS 456:2000 (the Indian Standard code of practice for plain and reinforced concrete), the design bond stress ($ au_{bd}$) for different grades of concrete is specified in Table-4. For M30 grade concrete, the design bond stress for plain bars in tension is given as 1.2 N/mm².
Breakdown of values for plain bars in tension from IS 456:2000:
- For M20: 1.0 N/mm²
- For M25: 1.2 N/mm²
- For M30: 1.2 N/mm²
- For M35: 1.4 N/mm²
- For M40: 1.5 N/mm²
Therefore, for M30 grade concrete, the correct value is 1.2 N/mm². Note that for deformed (HYSD) bars, these values are increased by 60%.
Construction schedule is prepared after collecting
A)
number of operations
B)
output of labour
C)
output of machinery
D)
all the above
A construction schedule is a detailed plan that outlines the sequence of activities, the duration of each task, and the resources required to complete a project within a specific timeframe. To prepare an accurate schedule, a project manager must determine the total workload and the rate at which that work can be performed.
1. **Number of operations (a):** The scheduler must first break down the project into a Work Breakdown Structure (WBS) to identify every single operation or activity required. Without knowing the number and sequence of operations, a schedule cannot be created.
2. **Output of labour (b):** The duration of a task depends on the productivity (output) of the workforce. For example, knowing how many cubic meters of concrete a team of masons can lay per day is essential to calculate the time required for that activity.
3. **Output of machinery (c):** For mechanized tasks (e.g., excavation by an excavator), the capacity and efficiency of the machinery determine the speed of completion.
Since the total time for any activity is calculated as (Total Quantity of Work / Output per unit of resource), all three factors—the nature of operations, labour productivity, and machinery capacity—are critical inputs for preparing a construction schedule.
A foundation is called shallow if its depth, is
A)
one fourth of its width
B)
equal to its width
C)
half of its width
D)
three-fourth of its width
In foundation engineering, foundations are broadly classified into shallow and deep foundations based on the ratio of their depth (D) to their width (B).
1. **Shallow Foundation**: Traditionally, a foundation is considered 'shallow' if its depth is less than or equal to its width (D ≤ B). Some textbooks and codes (like Terzaghi's general approach) define it as D/B ≤ 1.
2. **Deep Foundation**: A foundation is considered 'deep' if its depth is significantly greater than its width (typically D/B > 4 to 5), such as piles or caissons.
Evaluating the options:
- Option (a) 'one fourth of its width' and (c) 'half of its width' are examples of shallow foundations, but they are specific cases, not the general defining limit.
- Option (b) 'equal to its width' represents the standard threshold (D = B) used in most technical definitions to distinguish the upper limit of shallow foundations.
- Option (d) 'three-fourth of its width' is also a specific case of a shallow foundation but not the defining limit.
Therefore, the most authoritative general definition for the boundary of a shallow foundation is when the depth is equal to its width.
A CPM family includes
A)
CPS (Critical Path Scheduling)
B)
CPP (Critical path Plotted)
C)
CPA (Critical Path Analysis)
D)
all the above
CPM stands for the Critical Path Method. In the field of construction management and project planning, CPM is a technique used to identify the sequence of crucial steps that determine the minimum time needed to complete a project. The process of identifying these paths, calculating floats, and analyzing the project schedule is formally known as Critical Path Analysis (CPA). Therefore, CPA is the analytical component and the 'family' or methodology associated with CPM. Options 'CPS' and 'CPP' are not standard industry terms used to describe the CPM methodology; they are distractors created for the examination.
The formula of quicklime is
A)
CaCO3
B)
Ca(OH)2
C)
CO2 CO3
D)
none of the above
Step-by-step reasoning:
1. Identify the chemical name of 'Quicklime': Quicklime is the common name for Calcium Oxide (CaO).
2. Analyze the given options:
- Option (a) CaCO3 is Calcium Carbonate, commonly known as limestone or chalk.
- Option (b) Ca(OH)2 is Calcium Hydroxide, commonly known as slaked lime.
- Option (c) CO2 CO3 is a combination of Carbon Dioxide and Carbonate ions, which is not a standard chemical formula for a single compound.
3. Since the correct formula for quicklime (CaO) is not listed in options a, b, or c, the correct choice is 'none of the above'.
The angle which an inclined surface makes with horizontal when a body placed on it is on the point of moving down, is called
A)
angle of repose
B)
angle of inclination
C)
angle of friction
D)
none of the above
The 'angle of repose' is defined as the maximum angle of an inclined plane at which an object placed on it remains stationary without sliding down. When the angle of the plane is increased to the point where the object is just about to move (the point of impending motion), this specific angle is called the angle of repose. Mathematically, if θ is the angle of repose and μ is the coefficient of static friction, then tan(θ) = μ.
Why other options are incorrect:
- b. Angle of inclination: This is a general term for any angle a surface makes with the horizontal; it does not specifically refer to the point of impending motion.
- c. Angle of friction: While numerically equal to the angle of repose for a single block on a plane, the angle of friction is defined as the angle between the normal reaction and the resultant of the normal reaction and the frictional force. The question specifically asks for the angle the 'surface makes with the horizontal', which is the definition of the angle of repose.
Time and progress chart of a construction is also known as
A)
Bar Chart
B)
Gantt chart
C)
Critical path method chart
D)
all the above
A time and progress chart is a graphical representation used in construction management to show the start and finish dates of various activities against a time scale. This specific type of chart is widely known as a Gantt chart, developed by Henry Gantt.
Detailed breakdown of options:
- Option (a) Bar Chart: While a Gantt chart is a type of bar chart, the term 'Gantt chart' is the specific technical name for the time and progress chart used in project scheduling.
- Option (b) Gantt chart: This is the correct technical term. It plots activities on the vertical axis and time intervals on the horizontal axis, allowing managers to track progress against the planned schedule.
- Option (c) Critical Path Method (CPM) chart: CPM is a network-based technique (using nodes and arrows) rather than a simple time-progress bar chart. It focuses on identifying the longest sequence of dependent activities to determine the minimum project duration.
- Option (d) All the above: Incorrect, as CPM is fundamentally different from a progress bar chart.
Equation of motion of a point in a straight line is
A)
v = u + ft
B)
2fs = v^2 - u^2
C)
s = ut + 1/2 ft^2
D)
all the above
The question asks for the equations of motion for a point moving in a straight line with constant acceleration. In these equations, 'u' represents initial velocity, 'v' represents final velocity, 'f' represents constant acceleration (commonly denoted as 'a' in modern textbooks), 't' represents time, and 's' represents displacement.
1. Option (a): v = u + ft. This is the first equation of motion, relating velocity, acceleration, and time.
2. Option (b): 2fs = v^2 - u^2. This is a rearrangement of the third equation of motion (v^2 = u^2 + 2as), relating velocity, acceleration, and displacement.
3. Option (c): s = ut + 1/2 ft^2. This is the second equation of motion, relating displacement, initial velocity, acceleration, and time.
Since all three options are mathematically valid equations of motion for a point moving in a straight line under constant acceleration, the correct choice is 'all the above'.
The section modulus Z of a rectangular section of width b and depth d is given by
A)
Z = bd3/24
B)
Z = bd3/6
C)
Z = bd3/12
D)
Z = bd3/3
Section modulus Z=I/y, I=bd^3/12, y=d/2 => Z=bd^2/6, listed as bd3/6.
Shear stress at any section of a shaft is maximum at
A)
the centre of the section
B)
at a distance r/2 from the centre
C)
the top of the surface
D)
a distance 3/4r from the centre
In the context of a shaft subjected to torsion (twisting), the shear stress ($ au$) at any radial distance $r$ from the center of the shaft is given by the torsion formula: $\tau = \frac{T \cdot r}{J}$, where $T$ is the applied torque and $J$ is the polar moment of inertia. This formula shows that the shear stress is directly proportional to the distance $r$ from the center. Therefore: 1) At the center of the section ($r = 0$), the shear stress is zero. 2) As $r$ increases, the shear stress increases linearly. 3) The maximum shear stress occurs at the outermost fiber of the shaft, where $r$ is equal to the radius $R$. The 'top of the surface' (or the outer boundary/perimeter) represents the maximum distance from the center. Thus, the shear stress is maximum at the surface of the shaft.
The period of storage of cement when stored in bags should not exceed more than
A)
1 month
B)
2 months
C)
3 months
D)
4 months
Cement is a hydraulic binder that undergoes a chemical reaction called hydration when it comes into contact with moisture. Even when stored in bags, atmospheric moisture can penetrate the packaging, leading to partial hydration and the formation of lumps (warehouse set), which significantly reduces the strength and setting properties of the cement. According to standard engineering practices and IS codes (Indian Standards), cement should be used as soon as possible after manufacture. For cement stored in bags, the recommended maximum storage period to ensure the retention of its design strength and quality is 3 months. Beyond this period, the strength loss becomes significant unless the cement is re-tested and found to meet the required specifications. Therefore, option (c) is the correct technical standard for storage duration.