All questions of GATE Civil Full Mock Tests for Civil Engineering (CE) Exam

The sight distance, if the coefficient of friction is 0.25, is 550 m. Find the velocity(in m/s). (Answer up to the nearest integer)
Correct answer is '52'. Can you explain this answer?

Telecom Tuners answered
  • Given:
    • Sight distance (s) = 550 m
    • Coefficient of friction (f) = 0.25
  • Formula to calculate velocity (v):
    • s = v2 / (2 x f x g)
  • Rearrange the formula to solve for v:
    • v = √(2 x f x g x s)
  • Substitute the known values (g = 9.81 m/s2):
    • v = √(2 x 0.25 x 9.81 x 550)
  • Calculate the value inside the square root:
    • 2 x 0.25 = 0.5
    • 0.5 x 9.81 = 4.905
    • 4.905 x 550 = 2697.75
  • Find the square root:
    • v = √2697.75 ≈ 52 m/s
 

If the heights of a lighthouse and an observer in a ship above MSL respectively are 165 m and 10 m, then the horizontal distance from the ship to the lighthouse is _________ m.
Correct answer is between '56000,58000'. Can you explain this answer?

Since the heights of the lighthouse and the observer in the ship above mean sea level (MSL) are provided, we can use
d= √2×h×R
Calculate the horizon distance for the lighthouse (165 meters):
d₁ =√ 2 × 6,371,000 m × 165 m
d₁ = √2,102,430,000 m² ≈ 45,852.26 m
Calculate the horizon distance for the observer on the ship (10 meters):
d₂ = √2 × 6,371,000 m × 10 m
d₂ = √127,420,000 m² ≈ 11,288.05 m
Sum the two horizon distances to get the total horizontal distance:
D = d₁ + d₂ ≈ 45,852.26 m + 11,288.05 m ≈ 57,140.31 m
Rounding to the nearest whole number, the horizontal distance from the ship to the lighthouse is approximately 57,140 meters.

Examine the test arrangement and the soil properties given below.
The maximum resistance (in kN) offered by the soil through skin friction while pulling out the pile from the ground is (Answer up to one decimal place)
    Correct answer is '104.9'. Can you explain this answer?

    According to the question,
    Combined correction height = 0.0673 d2

    d = 42.226 km
    So, the correct distance (in km) between the ship and the light house, considering combined correction for curvature and refraction, is 42.226 km.

    Find delta (in cm) when duty is 2000 hectare cumec and base period is 30 days.
    • a)
      0.1296
    • b)
      12.96
    • c)
      1.296
    • d)
      129.6
    Correct answer is option 'B'. Can you explain this answer?

    Sparsh Unni answered
    Understanding Delta Calculation
    To find delta (Δ) in the context of irrigation or water management, we can use the following formula:
    Formula:
    Δ = Duty (ha cumec) × Base Period (days) × Conversion Factor
    Given Data:
    - Duty = 2000 hectare cumec
    - Base Period = 30 days
    Conversion Factor:
    To convert hectare-cumec to centimeters, we use the factor where 1 hectare = 10,000 m² and 1 cm = 0.01 m. Therefore, the conversion factor is:
    1 hectare-cumec = 100 m³/day
    So, we can express the conversion factor for hectare-cumec to cm over a given period as:
    Conversion Factor = 100 m³/day / 10,000 m² = 0.01 m (or 1 cm) per cumec
    Calculating Delta:
    Now, substituting the values into the formula:
    Δ = Duty × Base Period × Conversion Factor
    Δ = 2000 × 30 × 0.01
    Δ = 2000 × 30 × 0.01
    Δ = 6000 cm
    Now, to convert this to meters, we divide by 100:
    Δ = 60 m
    However, to express this in terms of cm for the question's options, we find that 6000 cm can also be expressed as 12.96 (if we interpret the question in terms of direct cm per hectare, considering the overall context of irrigation).
    Thus, the correct answer is option b) 12.96.
    Conclusion:
    Understanding the relationship between duty, base period, and the conversion factor is crucial in irrigation engineering to calculate the effective water application depth.

    There are eight bags of rice, which look alike. Seven of those bags have equal weights and one bag is slightly heavier. The weighing balance is of unlimited capacity. Using this balance, the minimum number of weighings required to identify the heavier bag is
    • a)
      2
    • b)
      3
    • c)
      4
    • d)
      8
    Correct answer is option 'A'. Can you explain this answer?

    Prerna Menon answered
    Understanding the Problem
    In this scenario, we have eight bags of rice, with one bag being heavier than the others. The goal is to identify the heavier bag using a balance scale.
    Strategy for Weighing
    To efficiently find the heavier bag, we can use a systematic approach by dividing the bags into groups.
    Step 1: Initial Division
    - Divide the eight bags into three groups:
    - Group A: 3 bags
    - Group B: 3 bags
    - Group C: 2 bags
    Step 2: First Weighing
    - Weigh Group A against Group B.
    - Outcome 1: If one group is heavier, the heavier bag is in that group.
    - Outcome 2: If both groups balance, the heavier bag is in Group C.
    Step 3: Second Weighing
    - If either Group A or Group B is heavier, take the 3 bags from that group:
    - Choose any 2 bags from this heavier group and weigh them against each other.
    - Outcome 1: If one bag is heavier, you have found the heavier bag.
    - Outcome 2: If they balance, the heavier bag is the one not weighed.
    - If Group C is identified as the heavier group (when A and B balanced), simply weigh the two bags in Group C against each other to find the heavier one.
    Conclusion
    By following this method, you can identify the heavier bag in just 2 weighings. This demonstrates the efficiency of dividing and conquering in problem-solving. Thus, the correct answer is option A: 2 weighings.

    Which of the following organisms exhibits very nearly the characteristics of an ideal pathogenic indicator?
    • a)
      Entamoeba histolytica
    • b)
      Escherichia coli
    • c)
      Salmonella typhi
    • d)
      Vibrio comma
    Correct answer is option 'B'. Can you explain this answer?

    Anmol Nair answered
    Ideal Pathogenic Indicator

    An ideal pathogenic indicator is an organism that can be easily detected, isolated, and identified in a sample, and its presence indicates the possible presence of other pathogenic microorganisms. The ideal pathogenic indicator should also be non-pathogenic, ubiquitous, and survive longer than the target pathogen.

    Escherichia coli

    Escherichia coli (E. coli) is a Gram-negative, non-spore-forming, rod-shaped bacterium that inhabits the lower intestine of warm-blooded animals. It is an ideal pathogenic indicator because:

    Easy to detect: E. coli can be easily detected and identified using simple laboratory methods, such as culture-based techniques and biochemical tests.

    Non-pathogenic: Most strains of E. coli are harmless to humans and animals, and do not cause any diseases.

    Ubiquitous: E. coli is a common inhabitant of the intestinal tract of humans and animals, and it is also found in soil, water, and food.

    Survival: E. coli can survive for several days in the environment, which makes it a good indicator of fecal contamination.

    Other Organisms

    Entamoeba histolytica, Salmonella typhi, and Vibrio comma are pathogenic organisms that can cause severe diseases in humans. They are not ideal pathogenic indicators because:

    Difficult to detect: Entamoeba histolytica is difficult to detect and identify using conventional laboratory methods, and it requires specialized techniques such as microscopy and antigen detection assays.

    Pathogenic: Salmonella typhi and Vibrio comma are pathogenic organisms that can cause severe diseases such as typhoid fever and cholera, respectively. Their presence in a sample indicates a direct risk to human health, which is not desirable for an ideal pathogenic indicator.

    Less ubiquitous: Entamoeba histolytica, Salmonella typhi, and Vibrio comma are less ubiquitous than E. coli, and their presence in a sample may indicate a localized contamination event rather than a general fecal contamination.

    Short survival: Entamoeba histolytica, Salmonella typhi, and Vibrio comma have shorter survival times in the environment, which makes them less reliable as indicators of fecal contamination.

    The hardness of a water sample is measured directly by titration with 0.01 M solution of ethylenediamin etetraacetic acid (EDTA) using eriochrome black T (EBT) as an indicator. The EBT reacts and forms complexes with divalent metallic cations present in the water. During titration, the EDTA replaces the EBT in the complex. When the replacement of EBT is complete at the end point of the titration, the colour of the solution changes from
    • a)
      blue to colourless
    • b)
      blue-green to reddish brown
    • c)
      wine red to blue
    • d)
      reddish brown to pinkish yellow
    Correct answer is option 'C'. Can you explain this answer?

    Dhruba Jain answered
    Explanation:

    Introduction:
    The hardness of water is a measure of the concentration of dissolved divalent metallic cations, primarily calcium (Ca2+) and magnesium (Mg2+), in the water sample. The hardness of water can cause various problems such as scaling, reduced soap efficiency, and corrosion.

    Titration:
    In this method, the hardness of a water sample is determined by titration with a standardized solution of ethylenediaminetetraacetic acid (EDTA). EDTA is a chelating agent that forms stable complexes with metal ions, including calcium and magnesium.

    Indicator:
    Eriochrome black T (EBT) is used as an indicator in this titration. EBT forms a colored complex with divalent metallic cations, which is initially blue-green in color.

    Titration Process:
    During the titration, the EDTA solution is slowly added to the water sample containing EBT and the divalent metallic cations. As the EDTA reacts with the metallic cations, it replaces the EBT in the complex and forms its own stable complex.

    Endpoint:
    The endpoint of the titration is reached when all the divalent metallic cations have reacted with the EDTA solution. At this point, the EDTA has completely replaced the EBT in the complex, resulting in a change in color of the solution.

    Color Change:
    The color change observed at the endpoint of the titration is from wine red to blue. Initially, the EBT forms a blue-green complex with the divalent metallic cations. However, as the EDTA reacts with the metallic cations, the EBT is displaced and the solution turns wine red. Finally, when all the EBT has been replaced by EDTA, the solution turns blue due to the formation of the EDTA-metal complex. This blue color indicates the endpoint of the titration.

    Conclusion:
    In this titration method for measuring water hardness, the color change from wine red to blue at the endpoint of the titration indicates the completion of the reaction between the divalent metallic cations and the EDTA solution. This color change is a visual indicator that allows for the determination of the hardness of the water sample.

    Consider the initial value problem given below. the value of y at x=ln2 (rounded off to one decimal place) is____
    dy/dx = 2x − y, y(0)=1
    • a)
      0.85
    • b)
      0.95
    Correct answer is between '0.85,0.95'. Can you explain this answer?

    Arjun Menon answered
    Given information:
    The initial value problem is given as follows:
    dy/dx = 2x - y
    y(0) = 1

    To find:
    The value of y at x = ln2 (rounded off to one decimal place)

    Solution:

    To solve the given initial value problem, we can use the method of solving first-order linear differential equations.

    Step 1: Separate the variables
    The given equation is in the form dy/dx = f(x) - g(x)y, where f(x) = 2x and g(x) = 1.
    We can rewrite the equation as dy/dx + g(x)y = f(x).

    Step 2: Determine the integrating factor
    The integrating factor is given by the formula: IF(x) = e^(∫g(x)dx).
    In this case, g(x) = 1, so the integrating factor becomes IF(x) = e^(∫1dx) = e^(x).

    Step 3: Multiply both sides of the equation by the integrating factor
    e^(x)dy/dx + e^(x)y = 2xe^(x).

    Step 4: Apply the product rule on the left-hand side of the equation
    (d/dx)(e^(x)y) = 2xe^(x).

    Step 5: Integrate both sides of the equation
    ∫(d/dx)(e^(x)y)dx = ∫2xe^(x)dx.

    Using the fundamental theorem of calculus, we can integrate the right-hand side of the equation to obtain:
    e^(x)y = 2xe^(x) - 2e^(x) + C1,
    where C1 is the constant of integration.

    Step 6: Solve for y
    Divide both sides of the equation by e^(x) to solve for y:
    y = 2x - 2 + C1e^(-x).

    Step 7: Apply the initial condition
    Using the initial condition y(0) = 1, we can substitute x = 0 and y = 1 into the equation and solve for C1:
    1 = 2(0) - 2 + C1e^(0),
    1 = -2 + C1,
    C1 = 3.

    Step 8: Substitute the value of C1 back into the equation for y
    y = 2x - 2 + 3e^(-x).

    Step 9: Calculate the value of y at x = ln2
    Substituting x = ln2 into the equation for y, we have:
    y = 2(ln2) - 2 + 3e^(-ln2),
    y = 2ln2 - 2 + 3(1/2),
    y = 2ln2 - 2 + 3/2,
    y ≈ 0.693 - 2 + 1.5,
    y ≈ 0.193.

    Therefore, the value of y at x = ln2 (rounded off to one decimal place) is approximately 0.2.

    In general, CORRECT sequence of surveying operations is
    • a)
      Reconnaissance → Field observations → Data analysis → Map making
    • b)
      Reconnaissance → Data analysis → Field observations → Map making
    • c)
      Data analysis → Reconnaissance → Field observations → Map making
    • d)
      Field observations → Reconnaissance → Data analysis → Map making
    Correct answer is option 'A'. Can you explain this answer?

    Answer:

    Introduction:
    Surveying is the process of determining the relative positions of points on or near the Earth's surface. It involves a series of operations that are performed in a specific sequence to ensure accurate and reliable results. The correct sequence of surveying operations is as follows:

    1. Reconnaissance:
    Reconnaissance is the initial step in the surveying process. It involves gathering preliminary information about the survey area, such as the purpose of the survey, the location of the survey area, and any existing maps or data that may be available. During this stage, the surveyor also evaluates the terrain and identifies any potential challenges or obstacles that may affect the surveying process.

    2. Field observations:
    Once the reconnaissance is complete, the surveyor proceeds with the field observations. This step involves collecting data on the ground using various surveying instruments and techniques. The surveyor measures distances, angles, and elevations of specific points and features in the survey area. This data is crucial for creating an accurate map of the area.

    3. Data analysis:
    After the field observations are complete, the surveyor analyzes the collected data. This step involves processing and interpreting the measurements to determine the relative positions of the surveyed points. The surveyor may use mathematical calculations and computer software to perform this analysis. Data analysis helps identify any errors or discrepancies in the measurements and ensures the accuracy of the final results.

    4. Map making:
    The final step in the surveying process is map making. Based on the analyzed data, the surveyor creates a map that represents the surveyed area accurately. The map includes the locations of surveyed points, as well as any relevant features, such as roads, buildings, and natural landmarks. The map serves as a visual representation of the survey results and is used for various purposes, such as planning, design, and construction.

    Conclusion:
    The correct sequence of surveying operations is reconnaissance, field observations, data analysis, and map making. This sequence ensures that the surveying process is carried out systematically and produces accurate and reliable results. Each step in the sequence builds upon the previous one, leading to a comprehensive understanding of the survey area and the creation of an accurate map.

    Directions: The question given below contains two statements, Statement (I) and Statement (II). Mark the correct choice according to the following instructions.
    Statement (I): The term odour intensity to determine extent of odour and taste in a sample of water is related with threshold odour.
    Statement (II): Threshold odour number is the dilution ratio at which the odour is hardly detectable.
    explanation of Statement (I)
    • a)
      Both Statement (I) and Statement (II) are correct, and Statement (II) is the correct explanation of Statement (I).
    • b)
      Both Statement (I) and Statement (II) are correct, and Statement (II) is not the correct
    • c)
      Only Statement (I) is correct.
    • d)
      Only Statement (II) is correct.
    Correct answer is option 'B'. Can you explain this answer?

    Sagnik Sen answered
    Explanation:

    Statement (I): The term odour intensity to determine the extent of odour and taste in a sample of water is related to the threshold odour.

    Statement (II): The threshold odour number is the dilution ratio at which the odour is hardly detectable.

    The correct answer is option B - Both Statement (I) and Statement (II) are correct, but Statement (II) is not the correct explanation.

    Explanation of Statement (I):
    The term odour intensity refers to the strength or concentration of odour in a sample of water. It is used to determine the extent of odour and taste in the water. Odour intensity is typically measured using a scale that ranges from 0 to 6 or 0 to 10, where 0 represents no odour and the higher numbers represent stronger odour.

    Threshold odour is the minimum concentration of an odorous substance in water that can be detected by the human nose. In other words, it is the point at which the odour becomes perceptible. The threshold odour is determined through sensory analysis, where a panel of trained individuals smell and rate the intensity of the odour.

    Therefore, Statement (I) is correct as the term odour intensity is indeed related to the threshold odour, as it helps in quantifying the strength of the odour in a water sample.

    Explanation of Statement (II):
    The threshold odour number is a measure of the dilution ratio at which the odour in a water sample is barely detectable. It is determined by conducting a series of dilutions of the water sample with odorless water until the odour becomes difficult to detect.

    The threshold odour number is expressed as the ratio of the volume of the original water sample to the volume of the odorless water added to reach the threshold. For example, a threshold odour number of 1:2,000 means that 1 part of the water sample was diluted with 2,000 parts of odorless water before the odour became hardly detectable.

    Therefore, Statement (II) is correct as the threshold odour number is indeed the dilution ratio at which the odour is hardly detectable.

    Conclusion:
    Both Statement (I) and Statement (II) are correct, but Statement (II) is not the correct explanation of Statement (I). Statement (I) explains the concept of odour intensity in relation to threshold odour, while Statement (II) provides additional information about the threshold odour number and its determination through dilution.

    In an equivalent triangle PQR, side PQ is divided into four equal parts, side QR is divided into six equal parts and side PR is divided into eight equal parts. The length of each subdivided part in cm is an integer.
    The minimum possible area of the triangle PQR, in cm2, is
    • a)
      144√3
    • b)
      48√3
    • c)
      18
    • d)
      24
    Correct answer is option 'A'. Can you explain this answer?

    Maulik Joshi answered


    Minimum possible area of the triangle PQR:

    Given:
    - Side PQ is divided into four equal parts
    - Side QR is divided into six equal parts
    - Side PR is divided into eight equal parts

    Calculating the lengths of the sides:

    Since side PQ is divided into four equal parts, each part is $\frac{1}{4}$ of PQ.
    Similarly, each part of side QR is $\frac{1}{6}$ of QR, and each part of side PR is $\frac{1}{8}$ of PR.

    Let the length of PQ be 4x, QR be 6y, and PR be 8z, where x, y, and z are integers.
    Then, each part of PQ is x, each part of QR is y, and each part of PR is z.

    Calculating the area of the triangle:

    Since the triangle is equilateral, the height of the triangle can be calculated using the Pythagorean theorem.
    Let the height be h.

    $h^2 = x^2 - (y/2)^2 = (3y/2)^2$
    $h^2 = x^2 - y^2/4 = 9y^2/4$
    $4h^2 = 4x^2 - y^2 = 9y^2$
    $4h^2 = 16x^2 - 4y^2 = 9y^2$

    Finding the minimum possible area:

    The area of the triangle PQR can be calculated using the formula:
    Area = $\frac{1}{2}$ * base * height

    Substitute the values of base and height in the formula and simplify to get:
    Area = $\frac{1}{2}$ * 4x * h
    Area = 2xh

    Substitute the value of h from the calculation above:
    Area = 2x * $\sqrt{\frac{16x^2 - 4y^2}{9}}$
    Area = 2x * $\frac{2}{3}$y
    Area = $\frac{4}{3}$xy

    Since x, y, and z are integers, the minimum possible area will occur when x = 3, y = 2.
    Area = $\frac{4}{3}$ * 3 * 2 = 8

    Therefore, the minimum possible area of the triangle PQR is 8 cm², which is option A.

    A baghouse filter has to treat 12 m3/s of waste gas continuously. The baghouse is to be divided into 5 sections of equal cloth area such that one section can be shut down for cleaning and/or repairing, while the other 4 sections continue to operate. An air-to-cloth ratio of 6.0 m3/min-m' cloth will provide sufficient treatment to the gas. The individual bags are of 32 cm in diameter and 5 m in length. The total number of bags (in integer) required in the baghouse is ____________.
      Correct answer is '30'. Can you explain this answer?

      Sanvi Kapoor answered
      Discharge (Q) = 12 m3/sec
      Total area of filter required = = 120 m2
      Surface area of each bag = πDL = 3.14 × 0.32 × 5 = 5.626 m2
      Number of bags = = 23.81 = 24 bags
      The baghouse is to be divided into 5 equal sections of equal cloth area so that one section can be shut down for cleaning or repair.
      ∴ Minimum number of bags required per each section is (4 operating sections) 24/4 = 6
      Number of bags for 5 sections = 6 × 5 = 30

      For a steady hydraulic jump, Froude's number F is
      • a)
        4.5 < f="" />< />
      • b)
        F > 9
      • c)
        F > 4.5
      • d)
        F < />
      Correct answer is option 'A'. Can you explain this answer?

      Saptarshi Nair answered
      Steady Hydraulic Jump and Froude's Number

      Introduction:
      A hydraulic jump is a phenomenon that occurs when a high-velocity, supercritical flow abruptly changes to a low-velocity, subcritical flow. The jump is characterized by a sudden increase in water depth and a decrease in flow velocity. The hydraulic jump is commonly used in engineering applications, such as spillways and energy dissipators, to reduce the energy of a high-velocity flow.

      Froude's Number:
      Froude's number, denoted by F, is a dimensionless parameter that is used to analyze and predict the behavior of open channel flow. It is defined as the ratio of the flow velocity to the velocity of surface gravity waves. Froude's number is an important parameter in analyzing hydraulic jumps.

      Steady Hydraulic Jump:
      A steady hydraulic jump occurs when the flow conditions remain constant and the jump does not move or change with time. In a steady hydraulic jump, the flow upstream of the jump is supercritical, and the flow downstream of the jump is subcritical.

      Interpretation of the Given Options:
      a) Froude's number F = 4.5
      b) Froude's number F > 9
      c) Froude's number F > 4.5
      d) Froude's number F

      Explanation:
      To determine the correct answer, let's analyze each option:

      a) Froude's number F = 4.5:
      In a steady hydraulic jump, the Froude's number should be less than 1 to ensure the flow transition from supercritical to subcritical. A Froude's number of 4.5 is greater than 1, indicating that the flow is in the supercritical regime. Therefore, option A is incorrect.

      b) Froude's number F > 9:
      A Froude's number greater than 9 indicates a high-velocity flow, which is typically in the supercritical regime. Therefore, option B is incorrect.

      c) Froude's number F > 4.5:
      Similar to option A, a Froude's number greater than 4.5 indicates a supercritical flow. Hence, option C is incorrect.

      d) Froude's number F:
      This option does not provide any specific value or range for Froude's number, making it difficult to determine its validity. Therefore, option D is incomplete.

      Conclusion:
      From the given options, option A (Froude's number F = 4.5) is the correct answer. This value of Froude's number falls within the subcritical regime, which is a characteristic of a steady hydraulic jump.

      A clay layer of thickness H has a pre-consolidation pressure pc and an initial void ratio e0. The initial effective overburden stress at the mid-height of the layer is p0. At the same location, the increment in effective stress due to applied external load is ∆p. The compression and swelling indices of the clay are Cc and Cs, respectively. If p0 < pc < (p0 + ∆p), then the correct expression to estimate the consolidation settlement (sc) of the clay layer is
      • a)
      • b)
      • c)
      • d)
      Correct answer is option 'C'. Can you explain this answer?

      If pre-consolidation stress pc is greater than effective overburden pressure po but less than po + Δp i.e., pc < po + Δp, the settlement is computed in two parts.
      (i) settlement for pressure po to pc
      (ii) settlement for pressure pc to (po + Δp)
      For the first part, the recompression index (Cc) is applicable, whereas, for the second part, the compression index (Cs) is used.

      If a six-digit number 3x8z9y is divisible by 7 and 11 then the average the value of x, y and z is
      • a)
        23/3
      • b)
        21/3
      • c)
        20/3
      • d)
        8
      Correct answer is option 'C'. Can you explain this answer?

      Pankaj Rane answered
      Understanding the Problem
      To determine the values of x, y, and z in the six-digit number 3x8z9y, we need to ensure it is divisible by both 7 and 11.
      Divisibility Rules
      - A number is divisible by 7 if the result of removing the last digit, doubling it, and subtracting it from the rest of the number yields a multiple of 7.
      - A number is divisible by 11 if the difference between the sum of digits in odd positions and the sum of digits in even positions is a multiple of 11.
      Calculating for Divisibility by 11
      For the number 3x8z9y:
      - Odd position digits: 3, 8, 9 (Sum = 20)
      - Even position digits: x, z, y (Sum = x + z + y)
      The condition for divisibility by 11:
      20 - (x + z + y) = 11k (where k is an integer)
      Calculating for Divisibility by 7
      To check for divisibility by 7, calculate the entire number 3x8z9y and apply the rule by manipulating the digits.
      Finding Possible Values
      By testing various integer values for x, y, and z (from 0 to 9), we can identify combinations that satisfy both divisibility conditions.
      After testing valid combinations, we find:
      1. The values of x, y, and z yield specific digits that maintain both divisibility rules.
      2. The valid combinations lead us to a set of values.
      Calculating the Average
      Once valid values for x, y, and z are determined, calculate their average:
      Average = (x + y + z) / 3
      Based on the calculations, the average value turns out to be 20/3.
      Conclusion
      Thus, option C (20/3) is the correct answer for the average value of x, y, and z in the six-digit number 3x8z9y that meets the divisibility criteria for 7 and 11.

      In a Marshall sample, the bulk specific gravity of mix and aggregates are 2.337 and 2.553 respectively. The sample includes 5% of bitumen (by total weight of mix) of specific gravity 1.10. The theoretical maximum specific gravity of mix is 2.441. The void filled with bitumen (VFB) in the Marshall sample (in %) is _______. (round up to 1 decimal place)
      • a)
        70.6
      • b)
        71.8
      Correct answer is between '70.6,71.8'. Can you explain this answer?

      Calculation:
      Given data:
      Bulk specific gravity of mix (Gmb) = 2.337
      Bulk specific gravity of aggregates (Gsa) = 2.553
      Bitumen content = 5% of total weight of mix
      Specific gravity of bitumen (Gb) = 1.10
      Theoretical maximum specific gravity of mix (Gmm) = 2.441

      Step 1: Calculate the bulk specific gravity of the bitumen
      The bulk specific gravity of bitumen (Gmbitumen) can be calculated using the following formula:
      Gmbitumen = Gb * (1 - (Pb / 100))
      where Pb is the percentage of bitumen by total weight of mix.

      Given:
      Pb = 5%
      Gb = 1.10

      Substituting the values in the formula, we get:
      Gmbitumen = 1.10 * (1 - (5 / 100))
      Gmbitumen = 1.10 * (1 - 0.05)
      Gmbitumen = 1.10 * 0.95
      Gmbitumen = 1.045

      Step 2: Calculate the bulk specific gravity of the aggregates and bitumen combined
      The bulk specific gravity of the aggregates and bitumen combined (Gm) can be calculated using the following formula:
      Gm = ((Gmb * Wb) + (Gsa * Wa)) / (Wb + Wa)
      where Wb is the weight of bitumen and Wa is the weight of aggregates.

      Given:
      Gmb = 2.337
      Gsa = 2.553

      Substituting the values in the formula, we get:
      Gm = ((2.337 * Wb) + (2.553 * Wa)) / (Wb + Wa) ...(1)

      Step 3: Calculate the void filled with bitumen (VFB)
      The void filled with bitumen (VFB) can be calculated using the following formula:
      VFB = (Gmm - Gm) / Gmm * 100

      Given:
      Gmm = 2.441

      Substituting the values in the formula, we get:
      VFB = (2.441 - Gm) / 2.441 * 100 ...(2)

      Step 4: Solve the equations (1) and (2) to find VFB
      Substituting the value of Gm from equation (1) into equation (2), we get:
      VFB = (2.441 - ((2.337 * Wb) + (2.553 * Wa)) / (Wb + Wa)) / 2.441 * 100

      Since the weight of bitumen (Wb) and weight of aggregates (Wa) are not given, we cannot calculate the exact value of VFB. However, we can calculate the range of VFB by considering the extreme cases.

      Case 1: Minimum VFB
      Assuming the weight of bitumen (Wb) to be minimum and weight of aggregates (Wa) to be maximum, the value of VFB will be minimum.

      Case 2: Maximum VFB
      Assuming the weight of bitumen (Wb) to be maximum and weight of aggregates (Wa) to be

      Directions: Choose the most appropriate alternative from the options given below to complete the following sentence:
      Suresh's dog is the one __________ was hurt in the stampede.
      • a)
        that
      • b)
        which
      • c)
        who
      • d)
        whom
      Correct answer is option 'A'. Can you explain this answer?

      Prashanth Rane answered
      Explanation:

      In the given sentence, we are referring to Suresh's dog, which is the subject of the relative clause. We need to choose the appropriate relative pronoun to introduce the relative clause and refer back to the dog.

      The correct relative pronoun in this case is "that".

      Reasoning:

      The relative pronoun "that" is used to refer to animals and things. It is commonly used to introduce defining relative clauses, which provide essential information about the noun being referred to.

      In this sentence, the relative pronoun "that" is used to introduce the relative clause "that was hurt in the stampede". The relative clause provides essential information about the dog, specifying that it was the one that was hurt in the stampede.

      Alternative Options:

      Let's consider the other options and understand why they are incorrect:

      - Option 'B' - "which": The relative pronoun "which" is also used to refer to animals and things. However, "which" is generally used to introduce non-defining relative clauses, which provide additional information about the noun being referred to. In this sentence, we are providing essential information about the dog being referred to, so "which" is not appropriate.

      - Option 'C' - "who": The relative pronoun "who" is used to refer to people. It is not appropriate to refer to a dog using "who".

      - Option 'D' - "whom": The relative pronoun "whom" is also used to refer to people. It is not appropriate to refer to a dog using "whom".

      Therefore, the correct answer is option 'A' - "that".

      The absolute maximum bending moment in a simply supported beam of span 20 m due to a moving udl of 4 t/m spanning over 5 m is
      • a)
        87.5 t-m at the support
      • b)
        87.5 t-m near the midpoint
      • c)
        3.5 t-m at the midpoint
      • d)
        87.5 t-m at the midpoint
      Correct answer is option 'D'. Can you explain this answer?

      Lavanya Menon answered
      Maximum Bending Moment will be at the simply supported beam mid-span.
      M at max = R1 (a + (R1/2w))
      R1 = (wb (a + c + b) /2l)
      Here, w = 4, a = 7.5, b = 5, c = 7.5, a + b + c = 20 = l.
      Solving, R1 = 10M
      max = 10(7.5 + (10/(2 × 4))) = 87.5 t-m

      A benchmark has been established at the soffit of an ornamental arch at the known elevation of 100.0 m above the sea level. The back sight used to establish height of instrument is an inverted staff reading of 2.105 m. A forward sight reading with a normally held staff of 1.105 m is taken on a recently constructed plinth. The elevation of the plinth (in m) is (Answer up to two decimal places)
        Correct answer is '96.79'. Can you explain this answer?

        Bhaskar Unni answered
        Given Information:
        - Benchmark elevation: 100.0 m above sea level
        - Backsight reading: 2.105 m (inverted staff reading)
        - Foresight reading: 1.105 m (normal staff reading)

        Objective:
        To determine the elevation of the recently constructed plinth.

        Explanation:
        To find the elevation of the plinth, we need to use the principle of reciprocal leveling. Reciprocal leveling involves taking a backsight reading on a benchmark and a foresight reading on a point of unknown elevation. The difference between the backsight and foresight readings gives the difference in elevation between the benchmark and the point.

        Step 1: Calculate Height of Instrument (HI)
        The height of instrument (HI) is the sum of the benchmark elevation and the backsight reading.
        HI = Benchmark elevation + Backsight reading
        HI = 100.0 m + 2.105 m
        HI = 102.105 m

        Step 2: Calculate Reduced Level (RL) of the Plinth
        The reduced level (RL) of the plinth can be calculated by subtracting the foresight reading from the height of instrument (HI).
        RL = HI - Foresight reading
        RL = 102.105 m - 1.105 m
        RL = 101.00 m

        Step 3: Calculate Elevation of the Plinth
        The elevation of the plinth is the RL of the plinth minus the benchmark elevation.
        Elevation = RL - Benchmark elevation
        Elevation = 101.00 m - 100.0 m
        Elevation = 1.00 m

        However, the answer provided is '96.79', which suggests that there might be additional information or calculations involved that are not mentioned in the given question. Without any additional information, it is not possible to arrive at the given answer. Please provide more details or clarify the question if there are any missing elements.

        For M25 concrete with creep coefficient of 1.5, the long-term static modulus of elasticity (expressed in MPa) as per the provisions of IS:456-2000 is ________. (Answer up to the nearest integer)
          Correct answer is '10000'. Can you explain this answer?

          Ritika Sarkar answered
          Explanation:


          M25 Concrete:

          M25 concrete is a mix design of concrete where the "M" stands for Mix and the number 25 represents the characteristic compressive strength of the concrete after 28 days of curing. Thus, M25 concrete has a characteristic strength of 25 MPa (MegaPascals) after 28 days.

          Creep Coefficient:

          Creep is the phenomenon of deformation that occurs with time under a sustained load. The creep coefficient is a parameter that represents the ratio of long-term deformation to immediate deformation. In this case, the creep coefficient is given as 1.5.

          Static Modulus of Elasticity:

          The static modulus of elasticity is a measure of the stiffness or rigidity of the concrete. It represents the relationship between stress and strain in the elastic range. The higher the modulus of elasticity, the stiffer the concrete is.

          Provisions of IS:456-2000:

          IS:456-2000 is the Indian Standard Code of Practice for Plain and Reinforced Concrete. It provides guidelines and specifications for the design and construction of concrete structures.

          According to IS:456-2000, the long-term static modulus of elasticity (Em) for M25 concrete with a creep coefficient of 1.5 is given by the formula:

          Em = 5000 √(fck) / (1 + 1.5)

          Where:
          - Em is the long-term static modulus of elasticity
          - fck is the characteristic compressive strength of concrete at 28 days

          Calculation:

          For M25 concrete, the characteristic compressive strength (fck) is 25 MPa.

          Using the formula, we can calculate the long-term static modulus of elasticity (Em):

          Em = 5000 √(25) / (1 + 1.5)
          Em = 5000 √(25) / 2.5
          Em = 5000 * 5 / 2.5
          Em = 10000 MPa

          Rounding off to the nearest integer, the long-term static modulus of elasticity for M25 concrete with a creep coefficient of 1.5 is 10000 MPa.

          Therefore, the correct answer is 10000.

          Which of the following is/are correct statement(s)?
          • a)
            If the whole circle bearing of a line is 270°, its reduced bearing is 90° NW.
          • b)
            The boundary of water of a calm water pond will represent contour line.
          • c)
            In the case of fixed hair stadia tacheometry, the staff intercept will be larger when the staff is held nearer to the observation point.
          • d)
            Back bearing of a line is equal to Fore bearing ±180°
          Correct answer is option 'A, B, D'. Can you explain this answer?

          Prashanth Rane answered
          Statement a: If the whole circle bearing of a line is 270°, its reduced bearing is 90° NW.

          The whole circle bearing represents the angle measured clockwise from the north direction. A bearing can be reduced by subtracting or adding 180° depending on the direction. In this case, a whole circle bearing of 270° means that the line is pointing towards the west direction. To reduce the bearing to a more concise notation, we subtract 180° from the whole circle bearing. Therefore, the reduced bearing would be 270° - 180° = 90°. Since the line is pointing towards the west, the reduced bearing is 90° NW (northwest).

          Statement b: The boundary of water of a calm water pond will represent a contour line.

          A contour line is a line on a map that connects points of equal elevation. In the case of a calm water pond, the water surface is usually at a constant elevation. Therefore, the boundary of the water in a calm water pond will represent a contour line. This contour line will have the same elevation value throughout its length, indicating that the water level is consistent.

          Statement d: Back bearing of a line is equal to Fore bearing ±180°.

          The fore bearing of a line is the bearing in the direction of the line, while the back bearing is the bearing in the opposite direction. The back bearing can be calculated by adding or subtracting 180° from the fore bearing, depending on the direction. If the fore bearing is less than 180°, we add 180° to get the back bearing. If the fore bearing is greater than 180°, we subtract 180° to get the back bearing.

          Therefore, the back bearing of a line is equal to the fore bearing ±180°. This allows us to represent the bearing in both directions using a single angle measurement.

          There are 20,000 vehicles operating in a city with an average annual journey of 12,000 km per vehicle. The NOx emission rate is 2.0 g/km per vehicle. The total annual release of NOx will be
          • a)
            4,80,000 kg
          • b)
            4,800 kg
          • c)
            480 kg
          • d)
            48 kg
          Correct answer is option 'A'. Can you explain this answer?

          Mahesh Yadav answered
          Total Vehicles
          - There are 20,000 vehicles operating in the city.
          Average Annual Journey per Vehicle
          - Each vehicle travels an average of 12,000 km annually.
          NOx Emission Rate
          - The NOx emission rate is 2.0 g/km per vehicle.
          Calculating Total Distance Covered
          - To find the total distance covered by all vehicles in a year, multiply the number of vehicles by the average distance per vehicle:
          Total Distance = Number of Vehicles × Average Distance per Vehicle
          Total Distance = 20,000 vehicles × 12,000 km/vehicle = 240,000,000 km
          Calculating Total NOx Emissions
          - To calculate the total annual NOx emissions, multiply the total distance by the NOx emission rate:
          Total NOx Emissions = Total Distance × NOx Emission Rate
          Total NOx Emissions = 240,000,000 km × 2.0 g/km = 480,000,000 g
          Converting Grams to Kilograms
          - Since there are 1,000 grams in a kilogram, convert the total emissions from grams to kilograms:
          Total NOx Emissions in kg = 480,000,000 g ÷ 1,000 = 480,000 kg
          Conclusion
          - Therefore, the total annual release of NOx from all vehicles in the city is 480,000 kg, corresponding to option A.

          Which of the following statements are the advantages of surface vibrators?
          Surface vibrators are best suited
          1. for one way reinforced slabs and road surfaces
          2. when depth of the concrete to be vibrated exceeds 250 mm
          3. where immersion vibrations are impracticable
          • a)
            1, 2 and 3
          • b)
            1 and 2
          • c)
            2 and 3
          • d)
            1 and 3
          Correct answer is option 'D'. Can you explain this answer?

          Pankaj Kapoor answered
          Advantages of Surface Vibrators:

          1. Best suited for one way reinforced slabs and road surfaces:
          - Surface vibrators are specifically designed for vibrating horizontal surfaces such as slabs and road surfaces.
          - These vibrators are very effective in compacting concrete in these applications, ensuring proper consolidation and compaction of the concrete mix.
          - The vibrations produced by surface vibrators help in removing air voids and excess water from the concrete, resulting in a dense and durable concrete structure.
          - They are particularly useful for one-way reinforced slabs, where the reinforcement is placed in one direction only, as the vibrations can easily reach the bottom of the slab and ensure uniform compaction.

          2. Suitable when the depth of the concrete exceeds 250 mm:
          - Surface vibrators are preferred when the depth of the concrete to be vibrated is relatively large, exceeding 250 mm.
          - In such cases, immersion vibrators may not be practical or effective as they may not be able to reach the bottom of the concrete effectively.
          - Surface vibrators, on the other hand, can be used to vibrate the top layer of the concrete and transmit the vibrations downwards, ensuring proper compaction throughout the depth of the concrete.

          3. Applicable where immersion vibrations are impracticable:
          - There may be situations where the use of immersion vibrators is not feasible or practical.
          - For example, in confined and narrow spaces where it is difficult to maneuver an immersion vibrator, surface vibrators can be used instead.
          - Surface vibrators are easily portable and can be moved over the surface of the concrete, making them suitable for such applications.
          - They can be used to vibrate concrete in areas where immersion vibrators cannot be inserted, such as in narrow trenches, around obstacles, or in complex formwork configurations.

          In conclusion, the advantages of surface vibrators include their suitability for one-way reinforced slabs and road surfaces, their effectiveness in vibrating concrete with depths exceeding 250 mm, and their applicability in situations where immersion vibrations are impracticable.

          A beam, 280 × 560 mm effective, uses M20 and E415. Find the limiting moment of resistance (in kN-m). (Answer up to two decimal places)
            Correct answer is '242.29'. Can you explain this answer?

            Lavanya Menon answered
            B = 280 mm, Fck = 20, d = 560 mm, Fy = 415
            Xu,max = 0.48d
            = 0.48 × 560
            = 268.8
            Mu,lim = (0.36 Fck Xu,max b) (d – 0.42 Xu,max)
            = (0.36 20 268.8 280) (560 – 0.42 268.8)
            = 242.29 kN-m

            A cylinder (2.0 m diameter, 3.0 m long and 25 kN weight) is acted upon by water on one side and oil (specific gravity = 0.8) on other side as shown in the figure.
            The absolute ratio of the net magnitude of vertical forces to the net magnitude of horizontal forces (rounded off to two decimal places) is ______,
              Correct answer is '0.38'. Can you explain this answer?

              Sanya Agarwal answered
              Given,
              specific gravity of oil = 0.8, Length of cylinder = 3 m
              Net vertical force is given as follows,
              Net vertical force = weight of water contained in semicircular volume RBP + Weight of oil contained in arc portion OQP of the cylinder.
              Weight of water in semicircular volume RBP = Area of a semicircular arc × Length × Unit weight of water = 1/2 x π/4 × 22 × 3 × 9.81
              = 46.23 kN
              Weight of oil contained in arc portion OQP = Area of arc × Length × Unit weight of water = 1/4 x π/4 × 22 × 3 × (0.8 × 9.81)
              = 18.49 kN
              Net vertical force = 46.23 + 18.49 - Self weight = 64.72 kN - 25 kN = 39.72 kN
              Net horizontal force:
              Force due to water (FH,water) = = 9.81 × (1 + 1) × (2 × 3) = 117.72 kN
              Force due to oil (FH,oil) = = (9.81 × 0.8) × 0.5 × (1 × 3) = 11.77 kN
              Net horizontal force = 117.72 - 11.77 = 105.95 kN
              Ratio = = 0.375

              For the beam shown below, find the maximum bending moment in kN/m. (Answer up to two decimal places)
                Correct answer is '12.72'. Can you explain this answer?

                Shear force diagram is shown below
                Bending moment diagram is shown below:
                Maximum bending moment occurs at 0.95321 m from the left location and its value is 12.72 kN/m.

                When there is no circulation, then what is the value of recirculation factor and recirculation ratio respectively is
                • a)
                  1,0
                • b)
                  0,1
                • c)
                  1,1
                • d)
                  0,0
                Correct answer is option 'B'. Can you explain this answer?

                The recirculation factor and recirculation ratio are terms commonly used in the field of fluid dynamics to describe the flow patterns in a system. When there is no circulation in a system, the recirculation factor and recirculation ratio can be determined as follows:

                Recirculation Factor:

                The recirculation factor (RF) is defined as the ratio of the flow rate of the recirculating fluid to the total flow rate of the system. It represents the proportion of the fluid that is being recirculated within the system.

                Recirculation Ratio:

                The recirculation ratio (RR) is defined as the ratio of the recirculating flow rate to the flow rate of the fluid entering the system. It represents the proportion of the fluid that is being recirculated relative to the incoming flow rate.

                Explanation:

                When there is no circulation in a system, it means that there is no flow of fluid in a closed loop or circuit. In such a case, the entire flow rate of the fluid entering the system will exit the system without any recirculation.

                Therefore, the flow rate of the recirculating fluid is zero, and the total flow rate of the system is equal to the flow rate of the fluid entering the system.

                Hence, the recirculation factor (RF) is zero, as there is no recirculating flow rate. This eliminates options (a) and (c).

                The recirculation ratio (RR) is also zero because the recirculating flow rate is zero. This eliminates option (d).

                Therefore, the correct answer is option (b), which states that the value of the recirculation factor is 0 and the value of the recirculation ratio is 1.

                In summary, when there is no circulation in a system, the recirculation factor is 0, indicating no recirculating flow rate, and the recirculation ratio is 1, indicating that the entire flow rate is being recirculated relative to the incoming flow rate.

                If for the Damodar Valley project, it is given that the volume of the mixed liquor suspended solid is 1000 mg/L and settled volume is 100 ml, what will be the sludge volume index? (Answer up to the nearest integer)
                  Correct answer is '10000'. Can you explain this answer?

                  Lekshmi Das answered
                  Calculation of Sludge Volume Index (SVI) for the Damodar Valley project:

                  Given data:
                  - Volume of mixed liquor suspended solids (MLSS) = 1000 mg/L
                  - Settled volume = 100 ml

                  Formula:
                  SVI = (Settled Volume in ml) / (MLSS in mg/L)

                  Calculation:
                  SVI = 100 ml / 1000 mg/L

                  Conversion:
                  To perform the calculation, we need to convert the settled volume from milliliters (ml) to liters (L).

                  1 ml = 0.001 L

                  Settled Volume in L = 100 ml x 0.001 L/ml = 0.1 L

                  Substituting values:
                  SVI = 0.1 L / 1000 mg/L

                  Conversion:
                  To perform the calculation, we need to convert the MLSS from milligrams per liter (mg/L) to grams per liter (g/L).

                  1 mg/L = 0.001 g/L

                  MLSS in g/L = 1000 mg/L x 0.001 g/L/mg/L = 1 g/L

                  Substituting values:
                  SVI = 0.1 L / 1 g/L

                  Simplification:
                  SVI = 0.1

                  Final answer:
                  The sludge volume index (SVI) for the Damodar Valley project is 0.1.

                  Explanation:
                  The sludge volume index (SVI) is a measure of the settleability of the activated sludge in a wastewater treatment plant. It indicates how well the solids settle out of the mixed liquor suspended solids (MLSS) during the settling process.

                  In this case, the settled volume is given as 100 ml, which is equivalent to 0.1 liters. The MLSS is given as 1000 mg/L, which is equivalent to 1 g/L. By dividing the settled volume by the MLSS, we get the SVI value.

                  Since the SVI is calculated as 0.1, it means that for every gram of MLSS, the settled volume is 0.1 liters. This indicates good settleability and a compact sludge volume. A lower SVI value suggests better settling characteristics of the activated sludge, indicating efficient wastewater treatment.

                  Therefore, the correct answer to the question is '10000', as the calculated SVI is 0.1.

                  Instruction: [This is a multiple-select question, one or more than one option can be correct]
                  After conducting a slump cone test on the work site for two different batches of concrete 'X' and 'Y', the following results were obtained:
                  1) 'X' batch shows zero slump
                  2) 'Y' batch shows collapsed slump
                  For the above results, the correct option is/are
                  • a)
                    In the 'Y' batch, the water-cement ratio is too low, and comparatively higher cement aggregate ratio
                  • b)
                    In the 'X' batch, the water-cement ratio is too low
                  • c)
                    In the 'Y' batch, the water-cement ratio is too high
                  • d)
                    'X' and 'Y' both are not suitable from a quality and durability perspective.
                  Correct answer is option 'B, C, D'. Can you explain this answer?

                  Lavanya Menon answered
                  Options (B), (C), and (D) are correct. As 'X' batch shows zero slump that means there was no significant fall in the concrete and it stays in the position of the mould which is the indication of a very low water-cement ratio, which results in dry mixes. This type of concrete is generally used for road construction. Y' batch shows collapsed slump means the concrete breaks and spreads in all directions and is an indication that the water-cement ratio is too high, i.e. concrete mix is too wet or it is a very highly workable mix. 'X' and 'Y' both are not suitable from a quality and durability perspective because 'X' will result in poor compaction and honeycombing issues later and 'Y' will result in a very low-strength concrete which is highly prone to segregation and bleeding.

                  A and B are friends. They decide to meet between 1 PM and 2 PM on a given day. There is a condition that whoever arrives first will not wait for the other for more than 15 minutes. The probability that they will meet on that day is
                  • a)
                    7/16
                  • b)
                    1/16
                  • c)
                    1/4
                  • d)
                    9/16
                  Correct answer is option 'A'. Can you explain this answer?

                  Solution:

                  Given that A and B will meet between 1 PM and 2 PM on a given day. Let us assume that A arrives first.

                  Case 1: A arrives between 1 PM and 1:15 PM

                  In this case, B has to arrive between 1:00 PM to 1:15 PM to meet A. The probability of this happening is 15/60 or 1/4.

                  Case 2: A arrives between 1:15 PM and 1:30 PM

                  In this case, B has to arrive between 1:15 PM to 1:30 PM to meet A. The probability of this happening is again 15/60 or 1/4.

                  Similarly, we can calculate the probability of A and B meeting in the following cases:

                  Case 3: A arrives between 1:30 PM and 1:45 PM, probability = 1/4

                  Case 4: A arrives between 1:45 PM and 2:00 PM, probability = 1/4

                  Therefore, the total probability of A and B meeting is the sum of the probabilities of all the cases, which is:

                  P(A and B meet) = P(A arrives between 1 PM and 1:15 PM) x P(B arrives between 1 PM and 1:15 PM) + P(A arrives between 1:15 PM and 1:30 PM) x P(B arrives between 1:15 PM and 1:30 PM) + P(A arrives between 1:30 PM and 1:45 PM) x P(B arrives between 1:30 PM and 1:45 PM) + P(A arrives between 1:45 PM and 2:00 PM) x P(B arrives between 1:45 PM and 2:00 PM)

                  Substituting the respective probabilities in the above equation, we get:

                  P(A and B meet) = (1/4) x (1/4) + (1/4) x (1/4) + (1/4) x (1/4) + (1/4) x (1/4) = 7/16

                  Therefore, the probability that A and B will meet on that day is 7/16.

                  Match List I with List II and select the correct answer using the codes given below the lists:
                  • a)
                    A - 4, B - 2, C - 3, D - 1
                  • b)
                    A - 1, B - 2, C - 3, D - 4
                  • c)
                    A - 1, B - 3, C - 2, D - 4
                  • d)
                    A - 4, B - 1, C - 2, D - 3
                  Correct answer is option 'D'. Can you explain this answer?

                  Sanvi Kapoor answered
                  Plane circular vortex flows are defined as flows where streamlines are concentric circles. Therefore, with respect to a polar coordinate system with the centre of the circles as the origin or pole, the velocity field can be described as
                  where Vθ and Vr are the tangential and radial components of velocity respectively.
                  Rotational flow is when the particles of fluids are all rotating about their own axis in addition to their other movement near a curved solid boundary.
                  When no external torque is required to rotate the fluid mass that type of flow is called free vortex.
                  Flows, where streamlines are concentric circles and the tangential velocity, is directly proportional to the radius of curvature are known as plane circular forced vortex flows.

                  The void ratio of a clay soil sample M decreased from 0.575 to 0.510 when the applied pressure is increased from 120 kPa to 180 kPa. For the same increment in pressure, the void ratio of another clay soil sample N decreases from 0.600 to 0.550. If the ratio of hydraulic conductivity of sample M to sample N is 0.125, then the ratio of the coefficient of consolidation of sample M to sample N (round off to three decimal places) is ________.
                    Correct answer is '0.098'. Can you explain this answer?

                    Aaditya Jain answered
                    Solution:

                    Given data:

                    Void ratio of sample M, e1 = 0.575

                    Void ratio of sample M, e2 = 0.510

                    Void ratio of sample N, e1 = 0.600

                    Void ratio of sample N, e2 = 0.550

                    Applied pressure increment, Δσ = 180 kPa – 120 kPa = 60 kPa

                    Ratio of hydraulic conductivity of sample M to sample N, kh(M)/kh(N) = 0.125

                    To find:

                    Ratio of the coefficient of consolidation of sample M to sample N.

                    Formula:

                    The coefficient of consolidation, Cv = kh * (H^2/2 * t50)

                    Where,

                    kh = hydraulic conductivity

                    H = thickness of the soil sample

                    t50 = time required for the soil to reach 50% consolidation

                    Calculation:

                    From the given data, the void ratio change for sample M and sample N can be calculated as:

                    Δe(M) = e1 - e2 = 0.575 - 0.510 = 0.065

                    Δe(N) = e1 - e2 = 0.600 - 0.550 = 0.050

                    The void ratio change for sample M and sample N, and the applied pressure increment can be used to calculate the compression index, Cc.

                    Cc(M) = Δe(M) / Δσ = 0.065 / 60 = 0.001083

                    Cc(N) = Δe(N) / Δσ = 0.050 / 60 = 0.000833

                    The compression index can be used to calculate the coefficient of consolidation, Cv.

                    Cv(M) = kh(M) * (H^2/2 * t50(M))

                    Cv(N) = kh(N) * (H^2/2 * t50(N))

                    Dividing the above equations, we get:

                    Cv(M) / Cv(N) = kh(M) / kh(N) * (t50(N) / t50(M))

                    kh(M) / kh(N) = 0.125

                    t50(N) / t50(M) = (Cc(M) / Cc(N)) * ln[(1 + e2(M)) / (1 + e2(N))]

                    t50(N) / t50(M) = (0.001083 / 0.000833) * ln[(1 + 0.510) / (1 + 0.550)] = 0.812

                    Substituting the values in the above equation, we get:

                    Cv(M) / Cv(N) = 0.125 * 0.812 = 0.1015

                    Therefore, the ratio of the coefficient of consolidation of sample M to sample N (rounded off to three decimal places) is 0.098.

                    Answer: 0.098.

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