Strength of Materials 1000+ MCQ with answer for DRDO

1. The neutral axis of the cross-section a beam is that axis at which the bending stress is
A. Zero
B. Minimum
C. Maximum
D. Infinity
Answer : A

2. One molecule of oxygen is __________ times heavier than the hydrogen atom.
A. 12
B. 14
C. 16
D. 32
Answer : D

3. If a material expands freely due to heating it will develop
A. Thermal stresses
B. Tensile stress
C. Bending
D. No stress
Answer : D

4. Which of the following statement is wrong?
A. The deformation of the bar per unit length in the direction of the force is called linear strain.
B. The Poisson's ratio is the ratio of lateral strain to the linear strain.
C. The ratio of change in volume to the original volume is called volumetric strain.
D. The bulk modulus is the ratio of linear stress to the linear strain.
Answer : D

5. The rivets are used for __________ fastenings.
A. Permanent
B. Temporary
C. Semi-permanent
D. None of these
Answer : A

6. When a body is subjected to biaxial stress i.e. direct stresses (?_x) and (?_y) in two mutually perpendicular planes accompanied by a simple shear stress (?_xy), then minimum normal stress is
A. (?_x + ?_y)/2 + (1/2) × ?[(?_x - ?_y)² + 4 ?²_xy]
B. (?_x + ?_y)/2 - (1/2) × ?[(?_x - ?_y)² + 4 ?²_xy]
C. (?_x - ?_y)/2 + (1/2) × ?[(?_x + ?_y)² + 4 ?²_xy]
D. (?_x - ?_y)/2 - (1/2) × ?[(?_x + ?_y)² + 4 ?²_xy]
Answer : B

7. In a steady flow process, the ratio of
A. Heat transfer is constant
B. Work transfer is constant
C. Mass flow at inlet and outlet is same
D. All of these
Answer : D

8. The efficiency of Diesel cycle with decrease in cut-off
A. Increases
B. Decreases
C. First increases and then decreases
D. First decreases and then increases
Answer : A

9. In the tensile test, the phenomenon of slow extension of the material, i. e. stress increasing with the time at a constant load is called
A. Creeping
B. Yielding
C. Breaking
D. Plasticity
Answer : A

10. When gas is heated at constant pressure, the heat supplied is utilised in
A. Increasing the internal energy of gas
B. Doing some external work
C. Increasing the internal energy of gas and also for doing some external work
D. None of the above
Answer : C

11. For a beam, as shown in the below figure, the deflection at C is (where E = Young's modulus for the beam material, and I = Moment of inertia of the beam section.

A. Wl3/48 EI
B. Wa²b²/3EIl
C. [Wa/(a?3) x EIl] x (l² - a²)3/2
D. 5Wl3/384 EI
Answer : B

12. The limit of eccentricity for no tensile conditions for a column of circular section of diameter (D) is
A. d/4
B. d/8
C. d/12
D. d/16
Answer : B

13. The point of contraflexure is a point where
A. Shear force changes sign
B. Bending moment changes sign
C. Shear force is maximum
D. Bending moment is maximum
Answer : B

14. When cut-off ratio is __________ the efficiency of Diesel cycle approaches to Otto cycle efficiency.
A. Zero
B. 1/5
C. 4/5
D. 1
Answer : A

15. In a reversible adiabatic process, the ratio of T1/T2 is equal to
A. (p₂/p₁)? - 1/ ?
B. (p₁/p₂)? - 1/ ?
C. (v₂/v₁)? - 1/ ?
D. (v₁/v₂)? - 1/ ?
Answer : B

16. Which of the following is the correct statement?
A. For a given compression ratio, both Otto and Diesel cycles have the same efficiency.
B. For a given compression ratio, Otto cycle is more efficient than Diesel cycle.
C. For a given compression ratio, Diesel cycle is more efficient than Otto cycle.
D. The efficiency of Otto or Diesel cycle has nothing to do with compression ratio.
Answer : B

17. The __________ states that change of internal energy of a perfect gas is directly proportional to the change of temperature.
A. Boyle's law
B. Charle's law
C. Gay-Lussac law
D. Joule's law
Answer : D

18. The buckling load for a given column depends upon
A. Area of cross-section of the column
B. Length and least radius of gyration of the column
C. Modulus of elasticity for the material of the column
D. All of the above
Answer : D

19. Mond gas is obtained by
A. Partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast
B. Carbonisation of bituminous coal
C. Passing steam over incandescent coke
D. Passing air and a large amount of steam over waste coal at about 650°C
Answer : D

20. When a body is subjected to a direct tensile stress (?x) in one plane accompanied by a simple shear stress (?xy), the maximum normal stress i
A. (?x/2) + (1/2) × ?(?x² + 4 ?²xy)
B. (?x/2) - (1/2) × ?(?x² + 4 ?²xy)
C. (?x/2) + (1/2) × ?(?x² - 4 ?²xy)
D. (1/2) × ?(?x² + 4 ?²xy)
Answer : A

21. The general gas energy equation is (where Q1 - 2 = Heat supplied, dU = Change in internal energy, and W1 - 2 = Work done in heat units)
A. Q_{1 - 2} = dU + W_{1 - 2}
B. Q_{1 - 2} = dU - W_{1 - 2}
C. Q_{1 - 2} = dU/W_{1 - 2}
D. Q_{1 - 2} = dU × W_{1 - 2}
Answer : A

22. The value of gas constant (R) in S. I. units is
A. 0.287 J/kgK
B. 2.87 J/kgK
C. 28.7 J/kgK
D. 287 J/kgK
Answer : D

23. One Joule (J) is equal to
A. 1 N-m
B. 1 kN-m
C. 10 N-m/s
D. 10 kN-m/s
Answer : A

24. Diesel cycle consists of __________ processes.
A. Two constant volume and two isentropic
B. Two constant pressure and two isentropic
C. Two constant volume and two isothermal
D. One constant pressure, one constant volume and two isentropic
Answer : D

25. Which of the following is correct?
A. Absolute pressure = Gauge pressure + Atmospheric pressure
B. Gauge pressure = Absolute pressure + Atmospheric pressure
C. Atmospheric pressure = Absolute pressure + Gauge pressure
D. Absolute pressure = Gauge pressure - Atmospheric pressure
Answer : A

26. The amount of heat required to raise the temperature of __________ water through one degree is called kilojoules.
A. 1 g
B. 10 g
C. 100 g
D. 1000 g
Answer : D

27. The strain energy stored in a body due to suddenly applied load compared to when it is applied gradually is
A. Same
B. Twice
C. Four times
D. Eight times
Answer : C

28. A column is said to be a short column, when
A. Its length is very small
B. Its cross-sectional area is small
C. The ratio of its length to the least radius of gyration is less than 80
D. The ratio of its length to the least radius of gyration is more than 80
Answer : C

29. A concentrated load is one which
A. Acts at a point on a beam
B. Spreads non-uniformly over the whole length of a beam
C. Spreads uniformly over the whole length of a beam
D. Varies uniformly over the whole length of a beam
Answer : A

30. The increase in entropy of a system represents
A. Increase in availability of energy
B. Increase in temperature
C. Decrease in pressure
D. Degradation of energy
Answer : D

31. A thin cylindrical shell of diameter (D) and thickness (t) is subjected to an internal pressure (p). The ratio of longitudinal strain to volumetric strain is
A. (m - 1)/ (2m - 1)
B. (2m - 1)/ (m - 1)
C. (m - 2)/ (3m - 4)
D. (m - 2)/ (5m - 4)
Answer : D

32. In closed cycle gas turbine, the air is compressed
A. Isothermally
B. Isentropically
C. Polytropically
D. None of these
Answer : B

33. The buckling load for a given material depends on
A. Slenderness ratio and area of cross-section
B. Poisson's ratio and modulus of elasticity
C. Slenderness ratio and modulus of elasticity
D. Slenderness ratio, area of cross-section and modulus of elasticity
Answer : D

34. The efficiency of Joule cycle is
A. Greater than Carnot cycle
B. Less than Carnot cycle
C. Equal to Carnot cycle
D. None of these
Answer : B

35. The property of a material by virtue of which it can be beaten or rolled into plates is called
A. Malleability
B. Ductility
C. Plasticity
D. Elasticity
Answer : A

36. Slenderness of a column is zero when
A. Ends are firmly fixed
B. Column is supported on all sides throughout the length
C. Length is equal to radius of gyration
D. Length is twice the radius of gyration
Answer : D

37. One kg of ethylene (C2H4) requires 2 kg of oxygen and produces 22/7 kg of carbon dioxide and __________ kg of water or steam.
A. 9/7
B. 11/7
C. 7/4
D. 1/4
Answer : A

38. The ratio of root mean square velocity to average velocity of gas molecules at a particular temperature is
A. 0.086
B. 1.086
C. 1.086
D. 4.086
Answer : B

39. The compression ratio for petrol engines is
A. 3 to 6
B. 5 to 8
C. 15 to 20
D. 20 to 30
Answer : B

40. In an irreversible process, there is a
A. Loss of heat
B. No loss of heat
C. Gain of heat
D. No gain of heat
Answer : A

41. For the constant pressure and heat input, the air standard efficiency of gas power cycle is in the order
A. Dual cycle, Diesel cycle, Otto cycle
B. Otto cycle, Diesel cycle, Dual cycle
C. Dual cycle, Otto cycle, Diesel cycle
D. Diesel cycle, Otto cycle, Dual cycle
Answer : A

42. The stress induced in a body due to suddenly applied load compared to when it is applied gradually is
A. Same
B. Half
C. Two times
D. Four times
Answer : C

43. The most probable velocity of the gas molecules is given by
A. ?(KT/m)
B. ?(2KT/m)
C. ?(3KT/m)
D. ?(5KT/m)
Answer : B

44. A composite shaft consisting of two stepped portions having spring constants K? and K? is held between two rigid supports at the ends. Its equivalent spring constant is
A. K? K?
B. (K? + K?)/ 2
C. (K? + K?)/ K? K?
D. K? K?/ (K? + K?)
Answer : A

45. The expansion ratio (r) is the ratio of (where v1 = Volume at the beginning of expansion, and v2 = Volume at the end of expansion)
A. v₁/v₂
B. v₂/v₁
C. (v₁ + v₂)/v₁
D. (v₁ + v₂)/v₂
Answer : B

46. The behaviour of super-heated vapour is similar to that of
A. Perfect gas
B. Air
C. Steam
D. Ordinary gas
Answer : A

47. The assumption made in Euler's column theory is that
A. The failure of column occurs due to buckling alone
B. The length of column is very large as compared to its cross-sectional dimensions
C. The column material obeys Hooke's law
D. All of the above
Answer : D

48. One kg of carbon requires 4/3 kg of oxygen and produces __________ kg of carbon monoxide gas.
A. 8/3
B. 11/3
C. 11/7
D. 7/3
Answer : D

49. In a prismatic member made of two materials so joined that they deform equally under axial stress, the unit stresses in two materials are
A. Equal
B. Proportional to their respective moduli of elasticity
C. Inversely proportional to their moduli of elasticity
D. Average of the sum of moduli of elasticity
Answer : B

50. The area under the temperature-entropy curve (T - s curve) of any thermodynamic process represents
A. Heat absorbed
B. Heat rejected
C. Either (A) or (B)
D. None of these
Answer : C