STRENGTH OF MATERIAL [MOS ] MCQ –Online practice question -1

 STRENGTH OF MATERIAL [MOS ] 

MCQ –Online practice question -1

UNIT -1 SIMPLE STRSSES AND STRAINS

This set of Strength of Materials Multiple Choice Questions & ANSWERs (MCQs) focuses on “Strain”. 

1. The dimension of strain is? a) LT-2 b) N/m2 c) N d) Dimensionless . 

ANSWER: d Explanation: Strain is the ratio of change in dimension to original dimension. So it is dimensionless. 

2. What is tensile strain? a) The ratio of change in length to the original length b) The ratio of original length to the change in length c) The ratio of tensile force to the change in length d) The ratio of change in length to the tensile force applied . 

ANSWER: a Explanation: The tensile stress is the ratio of tensile force to the change i length. It is the stress induced in a body when subjected to two equal and opposite pulls. The ratio of change in length to the original length is the tensile strain. 

3. Find the strain of a brass rod of length 250mm which is subjected to a tensile load of 50kN when the extension of rod is equal to 0.3mm? a) 0.025 b) 0.0012 c) 0.0046 d) 0.0014 . 

ANSWER: b Explanation: Strain = dL/L = 0.3/250 = 0.0012. 

4. Find the elongation of an steel rod of 100mm length when it is subjected to a tensile strain of 0.005? a) 0.2mm b) 0.3mm c) 0.5mm d) 0.1mm . 

ANSWER: c Explanation: dL = strain x L = 0.005 x 100 = 0.5mm. 

5. A tensile test was conducted on a mild steel bar. The diameter and the gauge length of bat was 3cm and 20cm respectively. The extension was 0.21mm. What is the value to strain? a) 0.0010 b) 0.00105 c) 0.0105 d) 0.005 . 

ANSWER: b Explanation: Strain = dL/L = 0.21/200 = 0.0005. 

6. i) Strain is a fundamental behaviour of a material. ii) Strain does not have a unit. a) Both i and ii are true and ii is the correct explanation of i b) Both i and ii ate true but ii is not the correct explanation of i c) i is true but ii is false d) ii is true but i is false . 

ANSWER: b Explanation: Strain is measured in a laboratory that is why it is called a fundamental quantity. Also since it is the ratio of the dimension of length to the dimension of length, it is dimensionless. 

7. A tensile test was conducted on a steel bar. The gauge length of the bar was 10cm and the extension was 2mm. What will be the percentage elongation? a) 0.002 b) 0.02 c) 0.2 d) 2 . 

ANSWER: d Explanation: The percentage elongation = dL/L x 100 = 2/100 x 100 = 2. 

8. The lateral strain is ___________ a) The ratio of axial deformation to the original length b) The ratio of deformation in area to the original area c) The strain at right angles to the direction of applied load d) The ratio of length of body to the tensile force applied on it . 

ANSWER: c Explanation: The lateral strain is the strain at right angles to the direction of the applied load. The lateral strain is accompanied by the longitudinal strain. 

9. The unit of force in S.I. units is ? a) Kilogram b) Newton c) Watt d) Dyne . 

ANSWER: b Explanation: Force = mass x acceleration = kg x m/s2 = N. 

10. Which of the following is not the unit of distance? a) Angstrom b) Light year c) Micron d) Milestone . ANSWER: d Explanation: Milestone meANSWER achievement. it is not and unit of distance. 

11. A solid cube is subjected to equal normal forces on all its faces. The volumetric strain will be x-times the linear strain in any of the three axes when? a) X=1 b) X=2 c) X=3 d) X=4 . 

ANSWER: c Explanation: The volumetric strain is the change in dimension in three directions and the linear strain depends on the change in only one direction so the volumetric strain is 1 times the linear strain in any of the three directions. 

12. A rod 200cm long is subjected to an axial pull due to which it elongates about 2mm. Calculate the amount of strain? a) 0.001 b) 0.01 c) 0.02 d) 0.002 . 

ANSWER: a Explanation: The strain is given by = dL / L = 2/2000 = 0.001. 

13. Some structural members subjected to a long time sustained loads deform progressively with time especially at elevated temperatures. What is such a phenomenon called? a) Fatigue b) Creep c) Creep relaxation d) Fracture . 

14. Find the strain of a brass rod of length 100mm which is subjected to a tensile load of 50kN when the extension of rod is equal to 0.1mm? a) 0.01 b) 0.001 c) 0.05 d) 0.005 . 

ANSWER: b Explanation: Strain = dL/L = 0.1/100 = 0.001. This set of Strength of Materials 

Multiple Choice Questions & ANSWERs (MCQs) focuses on “Elasticity”. 

1. The property by which a body returns to its original shape after removal of the force is called __________ a) Plasticity b) Elasticity c) Ductility d) Malleability . 

ANSWER: b Explanation: When an external force acts on a body, the body tends to undergo some deformation. If the external force is removed and the body comes back to its original shape and size, the body is known as elastic body and this property is called elasticity. 

2. The property of a material by which it can be beaten or rolled into thin plates is called __________ a) Malleability b) Plasticity c) Ductility d) Elasticity . 

ANSWER: a Explanation: A material can be beaten into thin plates by its property of malleability. 

3. Which law is also called as the elasticity law? a) Bernoulli’s law b) Stress law c) Hooke’s law d) Poisson’s law . 

ANSWER: c Explanation: The hooke”s law is valid under the elastic limit of a body. It itself states that stress is proportional to the strain within the elastic limit. 

4. The materials which have the same elastic properties in all directions are called __________ a) Isotropic b) Brittle c) Homogeneous d) Hard . 

ANSWER: a Explanation: Same elastic properties in all direction is called the homogenity of a material. 

 5. A member which does not regain its original shape after removal of the load producing deformation is said __________ a) Plastic b) Elastic c) Rigid d) None of the mentioned . 

ANSWER: a Explanation: A plastic material does not regain its original shape after removal of load. An elastic material regain its original shape after removal of load. 

 6. The body will regain it is previous shape and size only when the deformation caused by the external forces, is within a certain limit. What is that limit? a) Plastic limit b) Elastic limit c) Deformation limit d) None of the mentioned . 

ANSWER: b Explanation: The body only regain its previous shape and size only upto its elastic limit. 

7. The materials which have the same elastic properties in all directions are called __________ a) Isotropic b) Brittle c) Homogenous d) Hard . ANSWER: a Explanation: Isotropic materials have the same elastic properties in all directions. 8. As the elastic limit reaches, tensile strain __________ a) Increases more rapidly b) Decreases more rapidly c) Increases in proportion to the stress d) Decreases in proportion to the stress . 

ANSWER: a Explanation: On reaching the tensile stress to the elastic limit after the proportionality limit, the stress is no longer proportional to the strain. Then the value of strain rapidly increases. 

 9. What kind of elastic materials are derived from a strain energy density function? a) Cauchy elastic materials b) Hypo elastic materials c) Hyper elastic materials d) None of the mentioned . 

ANSWER: c Explanation: The hyper elastic materials are derived from a strain energy density function. A model is hyper elastic if and only if it is possible to express the cauchy stress tensor as a function of the deformation gradient. 

10. What the number that measures an object’s resistance to being deformed elastically when stress is applied to it? a) Elastic modulus b) Plastic modulus c) Poisson’s ratio d) Stress modulus .

 ANSWER: a Explanation: The elastic modulus is the ratio of stress to strain. 

This set of Strength of Materials Multiple Choice Questions & ANSWERs (MCQs) focuses on “Stress & Strain Curve”. 

1. The slope of the stress-strain curve in the elastic deformation region is ____________ a) Elastic modulus b) Plastic modulus c) Poisson’s ratio d) None of the mentioned . 

ANSWER: a Explanation: The elastic modulus is the ratio of stress and strain. So on the stress strain curve, it is the slope. 

 2. What is the stress-strain curve? a) It is the percentage of stress and stain b) It is the relationship between stress and strain c) It is the difference between stress and strain d) None of the mentioned . 

ANSWER: b Explanation: The relationship between stress and strain on a graph is the stress strain curve. It represents the change in stress with change in strain. 

 This set of Strength of Materials Multiple Choice Questions & ANSWERs (MCQs) focuses on “Strain Constants – 1”. 

1. What will be the elastic modulus of a material if the Poisson’s ratio for that material is 0.5? a) Equal to its shear modulus b) Three times its shear modulus c) Four times its shear modulus d) Not determinable . 

ANSWER: b Explanation: Explanation: Elastic modulus = E Shear modulus = G E = 2G ( 1 + μ ) Given, μ= 0.5, E = 2×1.5xG E = 3G. 

3. A solid metal bat of uniform diameter D and length L is hung vertically from a ceiling. If the density of the material of the bar is 1 and the modulus of elasticity is E, then the total elongation of the bar due to its own weight will be ____________ a) L/2E b) L2 /2E c) E/2L d) E/2L2 . 

ANSWER: b Explanation: The elongation of bar due to its own weight is δ= WL/2AE Now W = ρAL There fore δ= L2 / 2E. 

4. A bar of diameter 30mm is subjected to a tensile load such that the measured extension on a gauge length of 200mm is 0.09mm and the change in diameter is 0.0045mm. Calculate the Poissons ratio? a) 1/3 b) 1/4 c) 1/5 d) 1/6 . 

ANSWER: a Explanation: Longitudinal strain = 0.09/200 Lateral strain = – 0.0045/30 Poissons ratio = – lateral strain/ longitudinal strain = 0.0045/30 x 200/0.09 = 1/3. 

 5. What will be the ratio of Youngs modulus to the modulus of rigidity of a material having Poissons ratio 0.25? a) 3.75 b) 3.00 c) 1.5 d) 2.5 . 

ANSWER: d Explanation: Modulus of rigidity, G = E/2(1 + μ) Therefore, E/G = 2x(1+0.25) = 2.5. 

 6. An experiment was done and it was found that the bulk modulus of a material is equal to its shear modulus. Then what will be its Poissons ratio? a) 0.125 b) 0.150 c) 0.200 d) 0.375 . 

ANSWER: a Explanation: We know that, μ = (3K – 2G) / (6K + 2G) Here K = G Therefore, μ = 3-2 / 6+2 = 0.125. 

7. A bar of 40mm dia and 40cm length is subjected to an axial load of 100 kN. It elongates by 0.005mm. Calculate the Poissons ratio of the material of bar? a) 0.25 b) 0.28 c) 0.30 d) 0.33 . 

ANSWER: d Explanation: Longitudinal strain = 0.150/400 = 0.000375 Lateral strain = – 0.005/40 = -0.000125 Poissons ratio = – lateral strain/longitudinal strain = 0.33. 

 This set of Strength of Materials Multiple Choice Questions & ANSWERs (MCQs) focuses on “Elastic Constants Relationship – 1”. 

1. How many elastic constants of a linear, elastic, isotropic material will be? a) 2 b) 3 c) 1 d) 4 . 

ANSWER: a Explanation: Isotropic materials have the same properties in all directions. The number of independent elastic constants for such materials is 2. out of E, G, K, and μ, if any two constants are known for any linear elastic and isotropic material than rest two can be derived. Examples are steel, aluminium, copper, gold. Orthotropic materials refer to layered structure such as wood or plywood. The number of independent elastic constants for such materials is 9. Non isotropic or anisotropic materials have different properties in different directions. They show non- homogeneous behaviour. The number of elastic constants is 21. 

 2. How many elastic constants of a non homogeneous, non isotropic material will be? a) 9 b) 15 c) 20 d) 21 . 

ANSWER: d Explanation: Non isotropic or anisotropic materials have different properties in different directions. They show non- homogeneous behaviour. The number of elastic constants is 21. 

3. How can be the Poissons ratio be expressed in terms of bulk modulus(K) and modulus of rigidity(G)? a) (3K – 4G) / (6K + 4G) b) (3K + 4G) /( 6K – 4G) c) (3K – 2G) / (6K + 2G) d) (3K + 2G) / (6K – 2G) . 

ANSWER: c Explanation: There are four elastic modulus relationships. the relation between Poissons ration, bulk modulus and modulus of rigidity is given as μ = (3K – 2G) / (6K + 2G). 

4. Calculate the modulus of resilience for a 2m long bar which extends 2mm under limiting axial stress of 200 N/mm2 ? a) 0.01 b) 0.20 c) 0.10 d) 0.02 . 

ANSWER: c Explanation: Modulus of resilience = f2 /2E = 200×2/2×2000 = 0.10. 

 5. In an experiment, the bulk modulus of elasticity of a material is twice its modulus of rigidity. The Poissons ratio of the material is ___________ a) 1/7 b) 2/7 c) 3/7 d) 4/7 . 

ANSWER: b Explanation: As we know, μ= (3K – 2G) / (6K + 2G) Given K = 2G Then, μ = (6G – 2G) / (12G + 2G) = 4/14 = 2/7. 

6. What will be the value of the Poisson’s ratio if the Youngs modulus E is equal to the bulk modulus K? a) 1/2 b) 1/4 c) 1/3 d) 3/4 . 

ANSWER: c Explanation: K = E / 3(1 – 2μ) Since K = E So (1-2μ) = 1/3 Therefore, μ = 1/3. 

7. What is the expression for modulus of rigidity in terms of modulus of elasticity and the Poissons ratio? a) G = 3E / 2(1 + μ) b) G = 5E / (1 + μ) c) G = E / 2(1 + μ) d) G = E/ (1 + 2μ) . 

ANSWER: c Explanation: The relation between the modulus of rigidity, modulus of elasticity and the Poissons ratio is given as G = E / 2(1 + μ). 

8. What is the relationship between Youngs modulus E, modulus of rigidity C, and bulk modulus K? a) E = 9KC / (3K + C) b) E = 9KC / (9K + C) c) E = 3KC / (3K + C) d) E = 3KC / (9K + C) . 

ANSWER: a Explanation: The relationship between E, K, C is given by E = 9KC / (3K + C). 

9. What is the limiting values of Poisson’s ratio? a) -1 and 0.5 b) -1 and -0.5 c) -1 and -0.5 d) 0 and 0.5 . 

ANSWER: d Explanation: The value of Poissons ratio varies from 0 to 0.5. For rubber, its value ranges from.45 to 0.50. 

10. What is the relationship between modulus of elasticity and modulus of rigidity? a) C = E / 2(1 + μ) b) C = E / (1 + μ) c) C = 2E / (1 + μ) d) C = 2E / 2(1 + μ) . 

ANSWER: c Explanation: The relation is given by calculating the tensile strain of square block is given by taking tensile strain in a diagonal. On equating that stains we get the relation, C = E / 2(1 + μ). 

This set of Strength of Materials Multiple Choice Questions & ANSWERs (MCQs) focuses on “Normal & Shear Stress”. 

1. In the given figure a stepped column carries loads. What will be the maximum normal stress in the column at B in the larger diameter column if the ratio of P/A here is unity? a) 1/1.5 b) 1 c) 2/1.5 d) 2 . 

ANSWER: c Explanation: Normal stress at B = Total load acting at B / Area of a cross-section at B = (P + P) / 1.5 A = 2P/ 1.5A = 2/1.5. 

2. The stress which acts in a direction perpendicular to the area is called ____________ a) Shear stress b) Normal stress c) Thermal stress d) None of the mentioned . 

ANSWER: b Explanation: Normal stress acts in a direction perpendicular to the area. Normal stress is of two types tensile and compressive stress. 

 3. Which of these are types of normal stresses? a) Tensile and compressive stresses b) Tensile and thermal stresses c) Shear and bending d) Compressive and plane stresses . 

ANSWER: a Explanation: The normal stress is divided into tensile stress and compressive stress. 

 4. In a body loaded under plane stress conditions, what is the number of independent stress components? a) 1 b) 2 c) 3 d) 6 . 

ANSWER: c Explanation: In a body loaded under plane stress conditions, the number of independent stress components is 3 I.e. two normal components and one shear component. 

 5. If a bar of large length when held vertically and subjected to a load at its lower end, its wonweight produces additional stress. The maximum stress will be ____________ a) At the lower cross-section b) At the built-in upper cross-section c) At the central cross-section d) At every point of the bar . 

ANSWER: b Explanation: The stress is the load per unit area. After the addition of weight in the bar due to its loading on the lower end the force will increase in the upper cross-section resulting in the maximum stress at the built-in upper cross-section. 

6. Which type of stress does in a reinforcement bar is taken by the concrete? a) Tensile stress b) Compressive stress c) Shear stress d) Bending stress . 

ANSWER: b Explanation: Concrete has the property of taking a good amount of compressive stress. So, In the reinforcement bar, the compressive stress is taken by the concrete. 

7. A material has a Poisson’s ratio of 0.5. If uniform pressure of 300GPa is applied to that material, What will be the volumetric strain of it? a) 0.50 b) 0.20 c) 0.25 d) Zero . 

ANSWER: d Explanation: As volumetric strain = (1-2μ)σ/E Here the value of μ is 0.5 so 1 – 2 * 0.5 becomes zero. Therefore whatever be the stress the value of volumetric strain will be zero. 

 8. A diagram which shows the variations of the axial load for all sections of the pan of a beam is called ____________ a) Bending moment diagram b) Shear force diagram c) Thrust diagram d) Stress diagram . 

ANSWER: d Explanation: The stress diagram shows the variation of the axial load for all sections of the pan. The bending moment diagram shows the variation of moment in a beam. The shear force diagram shows the variation in the shear force due to loading in the beam. 

9. The stress induced in a body, when subjected to two equal and opposite forces which are acting tangentially across the resisting section resulting the shearing of the body across its section is called ____________ a) Bending stress b) Compressive stress c) Shear strain d) Shear stress .

 ANSWER: d Explanation: Shear stress makes the body to shear off across the section. It is tangential to the area over which it acts. The corresponding strain is the shear strain. 

 10. What is the formula for shear stress? a) Shear resistance/shear area b) Force/unit area c) Bending strain/area d) Shear stress/length . 

ANSWER: a Explanation: When force is applied, the twisting divides the body. The resistance is known as shear resistance and shear resistance per unit area is known as shear stress.