Strength of Materials MCQ Solved Paper for UPSC CDS

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

2. If the value of n = 0 in the equation pvn = C, then the process is called
A. Constant volume process
B. Adiabatic process
C. Constant pressure process
D. Isothermal process
Answer : C

3. Youngs modulus of a wire is defined as the stress which will increase the length of wire compared to its original length by
A. Half
B. Same amount
C. Double
D. One-fourth
Answer : B

4. The absolute zero pressure can be attained at a temperature of
A. 0°C
B. 273°C
C. 273 K
D. None of these
Answer : D

5. The efficiency of Diesel cycle increases with
A. Decrease in cut-off
B. Increase in cut-off
C. Constant cut-off
D. None of these
Answer : A

6. Young's modulus is defined as the ratio of
A. Volumetric stress and volumetric strain
B. Lateral stress and lateral strain
C. Longitudinal stress and longitudinal strain
D. Shear stress to shear strain
Answer : C

7. The mass of excess air supplied is equal to
A. (23/100) × Mass of excess carbon
B. (23/100) × Mass of excess oxygen
C. (100/23) × Mass of excess carbon
D. (100/23) × Mass of excess oxygen
Answer : D

8. A process of heating crude oil to a high temperature under a very high pressure to increase the yield of lighter distillates, is known as
A. Cracking
B. Carbonisation
C. Fractional distillation
D. Full distillation
Answer : A

9. The atomic mass of oxygen is
A. 12
B. 14
C. 16
D. 32
Answer : C

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

11. The absolute zero temperature is taken as
A. 237°C
B. -273°C
C. -237°C
D. 273°C
Answer : B

12. According to Avogadro's law, the density of any two gases is __________ their molecular masses, if the gases are at the same temperature and pressure.
A. Equal to
B. Directly proportional to
C. Inversely proportional to
D. None of these
Answer : B

13. The ratio of lateral strain to the linear strain within elastic limit is known as
A. Young's modulus
B. Bulk modulus
C. Modulus of rigidity
D. Poisson's ratio
Answer : D

14. 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

15. Which of the following process can be made reversible with the help of a regenerator?
A. Constant pressure process
B. Constant volume process
C. Constant pvn process
D. All of these
Answer : D

16. Which of the following is the correct statement?
A. All the reversible engines have the same efficiency.
B. All the reversible and irreversible engines have the same efficiency.
C. Irreversible engines have maximum efficiency.
D. All engines are designed as reversible in order to obtain maximum efficiency.
Answer : C

17. Stirling and Ericsson cycles are
A. Reversible cycles
B. Irreversible cycles
C. Semi-reversible cycles
D. Quasi-static cycles
Answer : A

18. When a body is subjected to a direct tensile stress (?x) in one plane accompanied by a simple shear stress (?xy), the maximum shear stress is
A. (?_x/2) + (1/2) × ?(?_x² + 4 ?²_xy)
B. (?_x/2) - (1/2) × ?(?_x² + 4 ?²_xy)
C. (?_x/2) + (1/2) × ?(?_x² - 4 ?²_xy)
D. (1/2) × ?(?x² + 4 ?²_xy)
Answer : D

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

20. The mass of carbon per kg of flue gas is given by
A. (11/3) CO₂ + (3/7) CO
B. (3/7) CO₂ + (11/3) CO
C. (7/3) CO₂ + (3/11) CO
D. (3/11) CO₂ + (7/3) CO
Answer : A

21. The pressure exerted by an ideal gas is ________ of the kinetic energy of all the molecules contained in a unit volume of gas.
A. One-half
B. One-third
C. Two-third
D. Three-fourth
Answer : C

22. The main cause for th irreversibility is
A. Mechanical and fluid friction
B. Unrestricted expansion
C. Heat transfer with a finite temperature difference
D. All of the above
Answer : D

23. Modulus of rigidity is defined as the ratio of
A. Longitudinal stress to longitudinal strain
B. Volumetric stress to volumetric strain
C. Lateral stress to Lateral strain
D. Shear stress to shear strain
Answer : D

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

25. The deformation per unit length is called
A. Tensile stress
B. Compressive stress
C. Shear stress
D. Strain
Answer : D

26. 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

27. In a belt drive, the pulley diameter is doubled, the belt tension and pulley width remaining same. The changes required in key will be
A. Increase key length
B. Increase key depth
C. Increase key width
D. Double all the dimensions
Answer : C

28. Which is the incorrect statement about Carnot cycle?
A. It is used as the alternate standard of comparison of all heat engines.
B. All the heat engines are based on Carnot cycle.
C. It provides concept of maximising work output between the two temperature limits.
D. All of the above
Answer : B

29. The work ratio of simple gas turbine cycle depends upon
A. Maximum cycle temperature
B. Minimum cycle temperature
C. Pressure ratio
D. All of these
Answer : D

30. 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

31. In an extensive property of a thermodynamic system
A. Extensive heat is transferred
B. Extensive work is done
C. Extensive energy is utilised
D. None of these
Answer : D

32. The ratio of specific heat at constant pressure (cp) and specific heat at constant volume (cv) is always __________ one.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : C

33. The atomic mass of nitrogen is __________ oxygen.
A. Equal to
B. Less than
C. More than
D. None of these
Answer : B

34. 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

35. The section modulus of a circular section about an axis through its C.G., is
A. ?d²/4
B. ?d²/16
C. ?d³/16
D. ?d³/32
Answer : D

36. For a simply supported beam of length l, when a concentrated load W is applied in the centre of the beam, the maximum deflection is
A. 5WL³/ 384EI
B. WL³/384EI
C. WL³/ 348EI
D. WL³/ 48EI
Answer : D

37. The amount of heat required to raise the temperature of 1 kg of water through one Kelvin is called
A. Specific heat at constant volume
B. Specific heat at constant pressure
C. kilo-Joule
D. None of these
Answer : C

38. A cycle consisting of two constant pressure and two isentropic processes is known as
A. Carnot cycle
B. Stirling cycle
C. Otto cycle
D. None of these
Answer : D

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

40. If in the equation pvn = C, the value of n = ?, then the process is called
A. Constant volume process
B. Adiabatic process
C. Constant pressure process
D. Isothermal process
Answer : A

41. 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

42. If the radius of wire stretched by a load is doubled, then its Youngs modulus will be
A. Doubled
B. Halved
C. Becomes four times
D. None of the above
Answer : D

43. 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
nswer : B

44. A close cycle gas turbine gives __________ efficiency as compared to an open cycle gas turbine.
A. Same
B. Lower
C. Higher
D. None of these
Answer : C

45. The relation between Young's modulus (E), shear modulus (C) and bulk modulus (K) is given by
A. E = 3K.C/(3K + C)
B. E = 6K.C/(3K + C)
C. E = 9K.C/(3K + C)
D. E = 12K.C/(3K + C)
Answer : C

46. A masonry dam may fail due to
A. Tension in the masonry of the dam and its base
B. Overturning of the dam
C. Crushing of masonry at the base of the dam
D. Any one of the above
Answer : D

47. The general law of expansion or compression is pvn = C, The process is said to be hyperbolic, if n is equal to
A. 0
B. 1
C. ?
D. ?
Answer : B

48. A continuous beam is one which is
A. Fixed at both ends
B. Fixed at one end and free at the other end
C. Supported on more than two supports
D. Extending beyond the supports
Answer : C

49. Charles' law states that all perfect gases change in volume by __________ of its original volume at 0°C for every 1°C change in temperature, when pressure remains constant.
A. 1/27th
B. 1/93th
C. 1/173th
D. 1/273th
Answer : D

50. Relation between cp and cv is given by (where cp = Specific heat at constant pressure, cv = Specific heat at constant volume, ? = cp/cv, known as adiabatic index, and R = Gas constant)
A. cv/ cp =R
B. cp - cv = R
C. cv = R/ ?-1
D. Both (B) and (C)
Answer : D