Structural Mechanics & Hydraulics MCQs for APSC PWD & WRD JE 2025

30 Structural Mechanics & Hydraulics MCQs for APSC JE PWD & Water Resources 2025

Topics Covered

• Structural Mechanics: Stress and Strain
• Structural Mechanics: Beams and Bending
• Structural Mechanics: Trusses and Frames
• Hydraulics: Fluid Properties and Flow
• Hydraulics: Open Channel Flow and Pipes

Topic: Structural Mechanics: Stress and Strain

1. What is stress in structural mechanics?

a) Deformation per unit length b) Force per unit area c) Total elongation d) Ratio of length to area

Answer: b) Force per unit area
Stress is defined as force divided by cross-sectional area.

Topic: Structural Mechanics: Stress and Strain

2. What is strain?

a) Force applied to a material b) Change in length per original length c) Resistance to deformation d) Area under load

Answer: b) Change in length per original length
Strain measures deformation relative to original size.

Topic: Structural Mechanics: Stress and Strain

3. What is Young's modulus?

a) Ratio of shear stress to shear strain b) Ratio of normal stress to normal strain c) Total deformation d) Force per unit length

Answer: b) Ratio of normal stress to normal strain
It measures a material’s stiffness in tension or compression.

Topic: Structural Mechanics: Beams and Bending

4. What is the bending moment in a beam?

a) Force causing shear b) Moment causing bending c) Axial force along the beam d) Torque twisting the beam

Answer: b) Moment causing bending
It’s the internal moment resisting external loads.

Topic: Structural Mechanics: Beams and Bending

5. Where is the maximum shear stress in a rectangular beam?

a) Top surface b) Bottom surface c) Neutral axis d) Edges

Answer: c) Neutral axis
Shear stress peaks at the neutral axis in a rectangular section.

Topic: Structural Mechanics: Beams and Bending

6. What is the purpose of a cantilever beam?

a) Support loads on both ends b) Support loads on one fixed end c) Resist torsion d) Reduce deflection

Answer: b) Support loads on one fixed end
A cantilever is fixed at one end and free at the other.

Topic: Structural Mechanics: Trusses and Frames

7. What is a truss?

a) A structure with rigid joints b) A framework of triangular units c) A beam with multiple supports d) A column under compression

Answer: b) A framework of triangular units
Trusses use triangles for stability and load distribution.

Topic: Structural Mechanics: Trusses and Frames

8. What is the primary load in truss members?

a) Shear force b) Bending moment c) Axial force d) Torsional force

Answer: c) Axial force
Truss members primarily experience tension or compression.

Topic: Structural Mechanics: Trusses and Frames

9. What is a zero-force member in a truss?

a) A member under maximum load b) A member with no force under certain loads c) A member resisting shear d) A member under bending

Answer: b) A member with no force under certain loads
It provides stability but carries no load in specific conditions.

Topic: Structural Mechanics: Stress and Strain

10. What is Poisson’s ratio?

a) Ratio of axial stress to shear stress b) Ratio of lateral strain to axial strain c) Ratio of force to area d) Ratio of length to width

Answer: b) Ratio of lateral strain to axial strain
It measures transverse deformation relative to axial deformation.

Topic: Structural Mechanics: Beams and Bending

11. What is the neutral axis in a beam?

a) Line of maximum stress b) Line of zero stress c) Line of maximum deflection d) Line of shear force

Answer: b) Line of zero stress
The neutral axis experiences no tension or compression during bending.

Topic: Structural Mechanics: Beams and Bending

12. What is the maximum deflection in a simply supported beam with a central load?

a) At the supports b) At the midpoint c) At one-third span d) Uniform throughout

Answer: b) At the midpoint
Deflection peaks at the center under a central load.

Topic: Structural Mechanics: Trusses and Frames

13. What is the method of joints used for?

a) Calculating beam deflection b) Analyzing forces in truss members c) Determining shear stress d) Measuring strain

Answer: b) Analyzing forces in truss members
It uses equilibrium at each joint to find member forces.

Topic: Structural Mechanics: Stress and Strain

14. What is shear strain?

a) Change in length b) Angular deformation due to shear c) Axial elongation d) Volume change

Answer: b) Angular deformation due to shear
It measures distortion from shear forces.

Topic: Structural Mechanics: Trusses and Frames

15. What is a stable truss?

a) A truss with bending moments b) A truss that does not collapse under load c) A truss with flexible joints d) A truss under shear only

Answer: b) A truss that does not collapse under load
Stability depends on geometry and support conditions.

Topic: Hydraulics: Fluid Properties and Flow

16. What is viscosity?

a) Fluid density b) Resistance to flow c) Fluid pressure d) Fluid volume

Answer: b) Resistance to flow
Viscosity measures a fluid’s internal friction.

Topic: Hydraulics: Fluid Properties and Flow

17. What is Bernoulli’s principle?

a) Energy conservation in fluids b) Momentum increase in pipes c) Volume change in flow d) Pressure drop in static fluid

Answer: a) Energy conservation in fluids
It relates pressure, velocity, and elevation in steady flow.

Topic: Hydraulics: Fluid Properties and Flow

18. What is the unit of dynamic viscosity?

a) kg/m³ b) N·s/m² c) m/s d) kg/m

Answer: b) N·s/m²
It’s a measure of force per unit area over time.

Topic: Hydraulics: Open Channel Flow and Pipes

19. What is the Manning’s equation used for?

a) Pipe flow pressure b) Open channel flow velocity c) Fluid viscosity d) Pump efficiency

Answer: b) Open channel flow velocity
It calculates flow based on channel roughness and slope.

Topic: Hydraulics: Open Channel Flow and Pipes

20. What is hydraulic radius?

a) Pipe diameter b) Cross-sectional area divided by wetted perimeter c) Flow velocity d) Fluid depth

Answer: b) Cross-sectional area divided by wetted perimeter
It’s a key parameter in open channel flow.

Topic: Hydraulics: Fluid Properties and Flow

21. What is laminar flow?

a) Turbulent and chaotic flow b) Smooth and orderly flow c) High-velocity flow d) Stagnant flow

Answer: b) Smooth and orderly flow
It occurs at low Reynolds numbers with parallel streamlines.

Topic: Hydraulics: Open Channel Flow and Pipes

22. What is the Darcy-Weisbach equation used for?

a) Open channel velocity b) Head loss in pipes c) Fluid density d) Channel slope

Answer: b) Head loss in pipes
It calculates friction losses based on pipe roughness and flow.

Topic: Hydraulics: Fluid Properties and Flow

23. What is the Reynolds number?

a) Ratio of pressure to velocity b) Ratio of inertial to viscous forces c) Ratio of depth to width d) Ratio of flow to area

Answer: b) Ratio of inertial to viscous forces
It predicts whether flow is laminar or turbulent.

Topic: Hydraulics: Open Channel Flow and Pipes

24. What is critical depth in open channel flow?

a) Maximum depth of flow b) Depth where specific energy is minimum c) Depth at zero velocity d) Depth at maximum velocity

Answer: b) Depth where specific energy is minimum
It marks the transition between subcritical and supercritical flow.

Topic: Hydraulics: Fluid Properties and Flow

25. What is the specific weight of water?

a) 9.81 kN/m³ b) 1000 kg/m³ c) 1 kg/m³ d) 981 N/m²

Answer: a) 9.81 kN/m³
It’s the weight per unit volume of water at standard conditions.

Topic: Hydraulics: Open Channel Flow and Pipes

26. What is uniform flow in an open channel?

a) Flow with varying depth b) Flow with constant depth and velocity c) Flow with zero velocity d) Flow with changing slope

Answer: b) Flow with constant depth and velocity
It occurs when gravitational and frictional forces balance.

Topic: Hydraulics: Fluid Properties and Flow

27. What is hydrostatic pressure?

a) Pressure due to fluid motion b) Pressure due to fluid at rest c) Pressure due to viscosity d) Pressure due to turbulence

Answer: b) Pressure due to fluid at rest
It increases with depth in a static fluid.

Topic: Hydraulics: Open Channel Flow and Pipes

28. What is the Froude number?

a) Ratio of inertial to viscous forces b) Ratio of inertial to gravitational forces c) Ratio of pressure to velocity d) Ratio of depth to width

Answer: b) Ratio of inertial to gravitational forces
It classifies flow as subcritical, critical, or supercritical.

Topic: Hydraulics: Fluid Properties and Flow

29. What is continuity equation in hydraulics?

a) Energy balance in flow b) Mass conservation in flow c) Momentum increase d) Pressure drop

Answer: b) Mass conservation in flow
It states that flow rate remains constant in a closed system.

Topic: Hydraulics: Open Channel Flow and Pipes

30. What is head loss in pipe flow?

a) Increase in fluid velocity b) Loss of energy due to friction c) Gain in pressure d) Change in pipe diameter

Answer: b) Loss of energy due to friction
It’s caused by pipe roughness and flow resistance.