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Wednesday, 27 December 2017

SOM objective question and answer

                                                    Strength of Materials
1. Modulus of rigidity is defined as the ratio of
a) longitudinal stress to longitudinal strain
b) shear stress to shear strain
c) stress to strain
d) stress to volumetric strain Ans: b
2. If the Young's modulus of elasticity of a material is twice its modulus of rigidity, then the
Poisson's ratio of the material is
a) -1
b) -0.5
c) 0.5
d) zero Ans: d
3. Limit of proportionality depends upon
a) area of cross-section
b) type of loading
c) type of material
d) all of the above Ans: c
4. For an isotropic, homogeneous and elastic material obeying Hooke's law, number of
independent elastic constants is
a) 2
b) 3
c) 9
d) 1 Ans: a
5. In a thin cylindrical shell, the ratio of longitudinal stress to hoop stress is
a) 0.5
b) 1
c) 2
d) 4 Ans: c
6. If all the dimensions of a prismatic bar are doubled, then the maximum stress produced in it
under its own weight will
a) decrease
b) remain unchanged
c) increase to two times
d) increase to four times Ans: c
7. The relationship between Young's, modulus of elasticity E, bulk modulus K and Poisson's ratio
u is given by
a) E = 2K(l-2u.)
b) E = 3K(l + u)
c) E = 3K(l-2u)
d) E = 2K(l + u)
Ans: c
8. Limiting values of Poisson's ratio are
a) - 1 and 0.5
b) -land-0.5
c) 1 and - 0.5
d) 0 and 0.5
Ans: a
9. The elongation of a conical bar under its own weight is equal to
a) that of a prismatic bar of same length
b) one half that of a prismatic bar of same length
c) one third that of a prismatic bar of same length
d) one fourth that of a prismatic bar of same length
Ans: c
10. If a material has identical properties in all directions, it is said to be
a) homogeneous
b) isotropic
c) elastic
d) orthotropic
Ans: b
11. Two bars of different materials are of the same size and are subjected to same tensile forces.
If the bars have unit elongations in the ratio of 4 : 7, then the ratio of moduli of elasticity of the
two materials is
a) 7:4
b) 4:7
c) 4:17
d) 16 :49
Ans: a
12. A prismatic bar of volume V is subjected to a tensile force in longitudinal direction.
If Poisson's ratio of the material is u and longitudinal strain is e, then the final volume of the bar
a) (l + e)(l-u)2V
b) (l-e)2(l + ue)V
c) (l + e)(l-ne)2V
d) (l-ue)3V
Ans: c
13. If a composite bar of steel and copper is heated, then the copper bar will be under
a) tension
b) compression
c) shear
d) torsion
Ans: b
14. Effective length of a weld is equal to
a) overall length - weld size
b) overall length - throat thickness
c) overall length - 2 x weld size
d) overall length - 2 x throat thickness
Ans: c
15. Size of a right angled fillet weld is given by
a) 0.707 x throat thickness
b) 0.414 x throat thickness
c) 2.0 x throat thickness
d) throat thickness
Ans: b
16. The effective length of a fillet weld designed to transmit axial load shall not be less than
a) 2 x size of weld
b) 4 x size of weld
c) 6 x size of weld
d) 10 x size of weld
Ans: b
17. Size of fillet weld with unequal legs is equal to
a) smaller leg length
b) longer leg length
c) throat thickness
d) average of smaller and longer leg lengths
Ans: a
18. Weakest section in a fillet weld is
a) throat of the fillet
b) smaller side
c) side parallel to force
d) side perpendicular to force
Ans: a
19. Effective throat thickness of a fillet weld is
a) 0.707 x size of weld
b) 1.414 x size of weld
c) a function of the angle between fusion faces
d) equal to the side of the fillet
Ans: c
20. According to Unwin's formula, the dia¬meter of rivet in mm to suit the t mm thickness of plate
is given by
a) 6t
b) 6Vt
c) 1.9-y/t
d) 1.5 t+ 4
Ans: b

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