BT-204 Basic Civil Engineering and Engineering Mechanics - Jun 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aState the D'Alembert's principle and its application.
   How to answer

   • State D'Alembert's principle: $\sum \mathbf{F} - m\mathbf{a} = 0$, converting dynamic problem into equivalent static equilibrium problem.
   • Define inertia force or reverse effective force ($-m\mathbf{a}$).
   • Describe applications: analyzing accelerating bodies, vehicle dynamics, connected bodies.
2. 7 Marks
   bWhat are different characteristics of stones and their methods of testing. Write the name of various types of stones which are used in building work?
   How to answer

   • Characteristics of good building stones: strength, durability, hardness, toughness, specific gravity, appearance, fire resistance.
   • Methods of testing stones: crushing strength test, water absorption test, impact test, attrition test, acid test.
   • List common stones used in construction: granite, marble, sandstone, limestone, slate, basalt/trap.
3. 7 Marks
   aWith neat sketch explain the principle of positioning with GPS.
   How to answer

   • Basic principle: trilateration using distances from multiple satellites.
   • Distance calculation: $d = c \times \Delta t$.
   • Need for minimum 4 satellites to determine 3D position ($x, y, z$) and receiver clock bias.
   • Neat sketch showing satellite constellation, intersecting spheres/ranges, and ground receiver.
4. 7 Marks
   bDiscuss the general principles that need to be observed in brick masonry construction.
   How to answer

   • Soaking bricks in water before use to prevent water absorption from mortar.
   • Laying bricks on a true horizontal plane with vertical joints staggered (proper bond).
   • Use of uniform joint thickness (10 mm) and fully filling vertical and horizontal joints.
   • Checking plumbness and level continuously using plumb bob and spirit level.
   • Limiting height of construction in a single day (max 1.5 m) and curing for at least 1-2 weeks.
5. 7 Marks
   aExplain various types of stone masonry. Draw typical sketches to illustrate them.
   How to answer

   • Classification into Rubble Masonry and Ashlar Masonry.
   • Subtypes of Rubble Masonry: uncoursed, coursed, random, dry rubble.
   • Subtypes of Ashlar Masonry: fine, rough tooled, rock/quarry faced, chamfered.
   • Sketches illustrating cross-sections or elevations of coursed rubble, random rubble, and ashlar masonry.
6. 7 Marks
   bWhat is mortar? Describe the estimation of mortar requirement.
   How to answer

   • Definition of mortar: paste of binding material (cement/lime), fine aggregate (sand), and water.
   • Functions of mortar in masonry.
   • Estimation of mortar: nominal volume vs dry volume.
   • Calculation for $1\text{ m}^3$ of brickwork (typically requires approx $0.25$ to $0.30\text{ m}^3$ wet mortar, dry volume taken as $1.25$ to $1.3$ times wet mortar).
   • Determining quantities of cement and sand based on mix ratio (e.g., 1:3, 1:4, 1:6).
7. 7 Marks
   aDiscuss the application of remote sensing in :

   1. i)Terrain analysis
   2. ii)Construction material inventories
   3. iii)Site investigation
   How to answer

   • Terrain analysis: elevation modeling (DEM), slope analysis, drainage pattern mapping, landform classification.
   • Construction material inventories: locating quarries, identifying borrow pits, mapping gravel/sand deposits, tracking resource extraction.
   • Site investigation: evaluating foundation conditions, identifying faults/fractures, analyzing groundwater presence, route alignment for roads/canals.
8. 7 Marks
   bState the assumptions used in simple bending and derive the bending equation.
   How to answer

   • List assumptions: beam is initially straight, material is homogeneous and isotropic, plane sections remain plane after bending, Hooke's law applies, etc.
   • Sketch beam segment undergoing bending of radius $R$.
   • Derive strain relation: $\epsilon = y/R$, hence $\sigma = E(y/R)$ or $\sigma/y = E/R$.
   • Consider moment of resistance $M = \int y \sigma \, dA = (E/R) \int y^2 \, dA = (E/R) I$.
   • Combine to obtain bending equation: $\frac{M}{I} = \frac{\sigma}{y} = \frac{E}{R}$.
9. 7 Marks
   aDescribe various types of windows.
   How to answer

   • Casement windows: hinged at the sides, open like doors.
   • Sash/sliding windows: panels slide vertically or horizontally.
   • Louvered/Venetian windows: inclined glass/timber slats for ventilation with privacy.
   • Bay and Bow windows: projecting outward from the external wall.
   • Clerestory and Dormer windows: placed high on walls or on sloping roofs for natural light.
   • Skylights and pivoted windows.
10. 7 Marks
    bAn effort of $180\text{ N}$ is required just to move a certain body up an inclined plane of angle $15^\circ$, the force being parallel to the plane. If the angle of inclination of the plane is made $20^\circ$, the effort required, again applied parallel to the plane, is found to be $210\text{ N}$. Find the weight of the body and co-efficient of friction.
    How to answer

    • Write equilibrium equation along plane for impending motion upward: $P = W \sin\theta + \mu W \cos\theta = W(\sin\theta + \mu\cos\theta)$.
    • Set up equation 1: $180 = W(\sin 15^\circ + \mu \cos 15^\circ)$.
    • Set up equation 2: $210 = W(\sin 20^\circ + \mu \cos 20^\circ)$.
    • Divide equation 1 by 2 or express in terms of $\phi$ where $\mu = \tan\phi$: $\frac{180}{210} = \frac{\sin(15^\circ + \phi)}{\sin(20^\circ + \phi)}$.
    • Solve for $\phi$, find $\mu = \tan\phi$, and subsequently calculate $W$.
11. 7 Marks
    aDetermine the diameter of rod $200\text{ m}$ long length vertically and subjected a axial pull of $325\text{ kN}$ at its lower end if its weight per cubic meter is $80\text{ kN}$ and working stress is $75\text{ MPa}$. Also determines the total elongation of rod. Take $E = 210\text{ GPa}$.
    How to answer

    • Maximum stress occurs at top support: $\sigma_{max} = \frac{P}{A} + \gamma L$.
    • Calculate stress from self-weight: $\gamma L = 80\text{ kN/m}^3 \times 200\text{ m} = 16000\text{ kN/m}^2 = 16\text{ MPa}$.
    • Stress due to applied load: $\sigma_P = \sigma_{max} - \gamma L = 75 - 16 = 59\text{ MPa}$.
    • Area $A = \frac{P}{\sigma_P} = \frac{325 \times 10^3}{59 \times 10^6}\text{ m}^2$, solve for diameter $d = \sqrt{4A/\pi}$.
    • Total elongation: $\delta L = \frac{PL}{AE} + \frac{\gamma L^2}{2E}$.
12. 7 Marks
    bState work energy principle. A uniform cylinder of $125\text{mm}$ radius has a mass of $0.15\text{ kg}$ this cylinder rolls along the horizontal surface without slipping with a translation velocity of $20\text{cm/s}$. Determine its total kinetic energy.
    How to answer

    • State Work-Energy Principle: The work done by all resultant forces acting on a body equals the change in its kinetic energy ($W = \Delta KE$).
    • Write formula for kinetic energy of a rolling cylinder: $KE = \frac{1}{2}mv^2 + \frac{1}{2}I\omega^2$.
    • Substitute $I = \frac{1}{2}mr^2$ and $\omega = v/r$: $KE = \frac{1}{2}mv^2 + \frac{1}{4}mv^2 = \frac{3}{4}mv^2$.
    • Convert velocity to SI: $v = 0.20\text{ m/s}$.
    • Calculate $KE = \frac{3}{4} (0.15) (0.2)^2 = 0.75 \times 0.15 \times 0.04 = 0.0045\text{ J} = 4.5\text{ mJ}$.
13. 7 Marks
    aWrite the steps for finding the resultant of concurrent coplanar force system.
    How to answer

    • Resolve all forces into orthogonal components along X and Y axes ($F_x = F \cos\theta$, $F_y = F \sin\theta$).
    • Calculate algebraic sum of horizontal components: $\sum F_x$.
    • Calculate algebraic sum of vertical components: $\sum F_y$.
    • Find magnitude of resultant: $R = \sqrt{(\sum F_x)^2 + (\sum F_y)^2}$.
    • Determine inclination with X-axis: $\theta = \tan^{-1}\left|\frac{\sum F_y}{\sum F_x}\right|$ and identify correct quadrant.
14. 7 Marks
    bWhat are the constituent, desirable properties and types of Paints?
    How to answer

    • Constituents: Base (white lead, zinc oxide), Vehicle/binder (linseed oil), Pigment (gives color), Thinner/solvent (turpentine), Drier (litharge).
    • Desirable properties: good hiding/covering power, ease of application, weather resistance, durability, uniform drying without cracking.
    • Types of paints: oil paint, enamel paint, emulsion paint, distemper, cement paint, bituminous paint, aluminium paint.
15. 7 Marks
    aDefine the term contour and Explain in detail different methods of contouring.
    How to answer

    • Definition of contour: imaginary line on ground joining points of equal elevation.
    • Direct method: tracing contour lines directly on the ground using leveling; highly accurate but slow and expensive.
    • Indirect method: spot levels taken at predetermined points and contours interpolated.
    • Techniques of indirect method: grid/square method, cross-section method, radial line (tacheometric) method.
16. 7 Marks
    bExplain with neat sketch for following :

    1. i)Traversing by the method of included angles
    2. ii)Traversing by the method of direct angles
    How to answer

    • Traversing by method of included angles: measured angles clockwise from the back station to the forward station; used in closed traverses; check $(2n \pm 4) \times 90^\circ$.
    • Traversing by method of direct angles: angles measured directly from the backsight line to the foresight line clockwise; convenient for open traverses.
    • Sketches illustrating theodolite setup at station, backsight, foresight, and the angle measured.