### Strength of Materials (Stresses and Strains)

Q.1. If all the dimensions of a prismatic bar of square cross section suspended freely from the ceiling of a roof are doubled then the total elongation produced by its own weight will increase

(a) eight times

(b) four times

(c) three times

(d) two times (IES 1996)

(a) eight times

(b) four times

(c) three times

(d) two times (IES 1996)

Q.2. For an isotropic material, the number of independent material constants are

(a) 1

(b) 2

(c) 3

(d) 4 (AMIE Winter 1999)

Q.3. In an experiment it is found that the bulk modulus of a material is equal to its shear modulus. The Poisson’s ratio is

(a) 0.125

(b) 0.250

(c) 0.375

(d) 0.500 (IES 1998)

Q.4. A given material has Young’s modulus E, modulus of rigidity G and Poisson’s ratio 0.25. The ratio of Young’s modulus to modulus of rigidity of the material is

(a) 3.75

(b) 3

(c) 2.5

(d) 1.5 (IES 1997)

Q.5. The bulk modulus of elasticity of a material is twice its modulus of rigidity. The Poisson’s ratio of the material is

(a) 1/7

(b) 2/7

(c) 3/7

(d) 4/7 (IES 2002)

Q.6. A cylindrical bar of 20 mm diameter and 1 m length is subjected to a tensile test. Its longitudinal strain is 4 times that of its lateral strain. If the modulus of elasticity is 2 x 10

^{5}N/mm^{2}, then its modulus of rigidity is
(a) 8 x 10

^{6}N/mm^{2}
(b) 8 x 10

^{5}N/mm^{2}
(c) 0.8 x 10

^{4}N/mm^{2}
(d) 0.8 x 10

^{5}N/mm^{2}(IES 1999)
Q.7. What would be the height to which a vertical concrete wall may be built given an ultimate compressive strength of 16 MPa and a safety factor of 4? The weight density of concrete is 20 kNm

^{-3}.
(a) 50 m

(b) 100 m

(c) 150 m

(d) 200 m

Q.8. A bar of uniform cross section is subject to uniaxial tension and develops a strain in the direction of the force of 1/800. Assuming m = 1/3, the change of volume per unit volume will be

(a) 1/1000

(b) 1/1200

(c) 1/2400

(d) 1/4800

Q.9. A bar 4 cm in diameter is subjected to an axial load of 4 t. The extension of the bar over a gauge length of 20 cm is 0.03 cm. The decreases in diameter is 0.0018 cm. The Poisson’s ratio is

(a) 0.25

(b) 0.30

(c) 0.33

(d) 0.35 (IES 1994)

Q.10. A bar 30 mm in diameter was subjected to tensile load of 54 kN and the measured extension on 300 mm gauge length was 0.112 mm and change in diameter was 0.00366 mm. Poisson’s ration will be

(a) 0.25

(b) 0.326

(c) 0.356

(d) 0.28

**Answer:**

1. b

2. d

3. a

4. c

5. b

6. d

7. d

8. c

9. b

10. b

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