# Strength Of Materials_mcq

obj_mom

June 2018

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## Transcript

Strength of Materials (Stresses & Strains) Q.1. The work done on a unit volume of material, as simple tensile force is gradually increased from zero to a value causing rupture, is called (a) modulus of elasticity (b) modulus of toughness (c) modulus of resilience (d) none of these Q.2. The unit of modulus of resilience is (a) N-m^-2 (b) Nm-m^-3 (c) N-m^-3 (d) none of these Q.3. ) lies in the range  For most metals, Poisson’s ratio  (a) 0.1 to 0.9 (b) 0.05 to 0.1 (c) 1 to 10 (d) 0.25 to 0.35 Q.4. If a material contains same elastic properties in all directions at any point of the body then it is called (a) anisotropic (b) orthotropic (c) isotropic (d) none of these Q.5. The stress level below which a material has a high probability of not failure under reversal of stress, is known as (a) elastic limit (b) endurance limit (c) proportional limit (d) tolerance limit Q.6. In fatigue of metals, the endurance limit is (a) less than yield stress (b) more than yield stress (c) equal to ultimate stress in a static test (d) none of these Q.7. kg. Given that, E = 2 x 106 kg/cm2 and the length of the cable is 10 m. Elongation of the cable due to the load will be   A steel cable of 2 cm diameter is used to lift a load of 500 (a) 0.5 cm (b) 0.25 cm (c) 1 cm (d) cm  2/ Q.8. A mild steel bar is in two parts having equal lengths. The area of cross section of Part I is double that of Part II. If the bar carries an axial load P, then the ratio of elongation in Part I to that in Part II will be (a) 2 (b) 4 (c) 1/2 (d) 1/4   Q.9. A bar of circular cross section varies uniformly from a cross section 2D to D. If extension of the bar is calculated treating it as a bar of average diameter, then the percentage error will be (a) 10 (b) 25 (c) 33.33 (d) 50 Q.10. A bar of length L and constant cross section(A) is hanging vertically. What would be total increase in length due to self weight(W)? (a) WL/AE (b) 2WL/AE (c) WL/2AE (d) none of these Answers:  1. b 2. b 3. d 4. c 5. b 6. c 7. b 8. c 9. a 10. c 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 Q.2. For an isotropic material, the number of independent material constants are (a) 1 (b) 2 (c) 3 (d) 4 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  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 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 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  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   = 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 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 Q.1. A material having identical properties in all directions, is called (a) elastic (b) homogeneous (c) isotropic (d) all the above Q.2. Match List I with List II and select the correct answer using the codes given below the lists: List I  A. Tenacity B. Plasticity C. Ductility D. Malleability List II 1. Continues to deform without much increase of stress 2. Ultimate strength in tension 3. Extension in a direction without rupture 4. Ability to be drawn out by tension to a small section without rupture Codes: (a) A2, B1, C4, D3 (b) A2, B1, C3, D4 (c) A1, B2, C4, D3 (d) A1, B2, C3, D4 Q.3. Match list I(properties) with list II(stress points labelled 1, 2, 3, and 4) in the stress-strain figure and select the correct answer using the codes given below the lists: List I  A. Yield point B. Proportional limit C. Rupture strength D. Ultimate strength List II Figure Codes: