Strength of Materials January 3, 2019 Editor 0 In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. The field of strength of materials deals with forces and deformations that result from their acting on a material. The complete theory began with the consideration of the behaviour of one and two dimensional members of structures. The deformation per unit length is called Tensile stress Compression stress Shear stress Strain Which of the following materials has the least modulus of elasticity? Glass Copper Steel Aluminium It states that the elongation is proportional to the force Pascal's law Hooke's law Young's theoram Farrell's law Stress on an object is____its applied force directly proportional to inversely proportional to less than greater than A rigid body under the action of external forces can be replaced by two masses placed at a fixed distance apart. The two masses form an equivalent dynamical system, if The sum of two masses is equal to the total mass of the body The sum of mass movement of inertia of masses about their centre of gravity is equal to the mass moment of inertia of the body The centre of gravity of the two masses coincides with that of the body. All of these. A static load is mounted at the centre of a shaft rotating at uniform angular velocity. This shaft will be designed for The maximum compressive stress (static) Fatigue loading The maximum tensile stress (static) The maximum bending moment (static) What are the material which show direction dependent properties, called? Homogeneous materials Anisotropic materials Viscoelastic materials Isotropic materials The deformation of a bar under its own weight as compared to that when subjected to a direct axial load equal to its own weight will be: One-fourth Double Half The same When a wire is stretched to double in length, the longitudinal strain produced in it is: 0.3 0.6 2.1 1.0 The elastic constant E, G and K are related by the expression: E= GK/K+G E= 3GK/K+2G E= 9GK/3K+G GK/2K+G The value of Poisson's ratio depends upon Nature of load, tensile or compressive Material of the test specimen Magnitude Dimensions of the test specimen Brittleness is opposite to Toughness Plasticity Melleability None of these Modulus of rigidity is defined as the ratio of Shear stress to shear strain Lateral stress to lateral strain Volumetric stress to volumetric strain Longitudinal stress to longitudina strain What is the arc of contact when in an involute tooth profile the pressure angle is 20° and path of contact is 45 mm? 32.65mm 27.89mm 47.89mm 12.5mm The suitable bearing for fluctuating loads is Needle-roller bearing Ball bearing Roller bearing Sleeve bearing If the slenderness ratio for column is 100, then it is said to be a____column. Long Medium Short None of these In case of a cam, the maximum value of the pressure angle is kept as 15° 20° 30° 45° Critical damping is a function of Mass and damping co-efficient Mass and stiffness Stiffness and damping coefficient Stiffness and natural frequency Hardness is resistance to: Indentation Abrasion Scratching All the above Impact strength of a material is Hardness Toughness Creep None of these During a tensile test on a specimen of 2 cm^2 cross section, maximum load is 110 KN and area of cross section at neck is 55 cm^2. Ultimate Tensile Strength (UTS) of specimen is 500 MPa 580 MPa 550 MPa 450 MPa Resilience of a material is fatigue creep shock loading resonant comdition Brittle material fail by shearing along the plane inclined at_____to the longitudinal axis 35-45 10-35 22-35 50-60 Limiting value of Poisson's ration are: 0 and 0.5 1 and 0.5 -1 and -0.5 -1 and 0.5 Which of the following statement is wrong? The deformation of the bar per unit length in the direction of force is called linear strain The Poisson's ratio isthe ratio of lateral strain to linear strain The ratio of change in volume to the original volume is called volumetric strain The bulk modulus is the ratio of linear stress to the linear strain The strength of the shaft is judged by the Length of the shaft Torque transmitted by the shaft Diameter of the shaft None of these The angle of twist is measured in Mils Gradians Radians Degrees The thermal stress in a bar is proportional to the change in temperature Directly Indirectly Both are correct None of these The thermal or temperature stress is a function of Increase in temperature Modulus of elasticity Coefficient of linear expansion All of these The bending moment at the free end of a cantilever beam is Zero Minimum Maximum None of these Calculating the normal stress acting on the plane of maximum shear stress, considering the following states of stress shown in figure. 30 MPa compression 30 Mpa tension 15 MPa compression 15 MPa tension A spring of radius 1 cm obeys Hooke's law. A mass of 2 kg is attached to the spring. Calculate the extension of the spring. The spring constant k is 110 N/m 0.1781 cm 17.81 m 0.1781 mm 0.1781 m When a square or rectangular block subjected to a shear load is in equilibrium, the shear stress in one plane is always associated with a complementary shear stress in the other plane at______degrees to it. 180 90 70 30 Spherical vessels are preferred over cylindrical shapes due to Easier to fabricate Light in weight for the same storing capacity Greater capacity Subjected to low value of hoop stress The relation between the diameter of a rivet (d) and plate thickness (t) is given by, d = 6√t d = 2√t d = 4√t d = 3√t What is the ratio between buckling load and safe load known as? Factor of safety Slenderness ratio Buckling factor None of these A measure of the resistence of a material to change of volume without change of shape Young's modulus Modulus of rigidity Bulk modulus Shear modulus The modulus of elasticity is known as Yiels strength Hooke's ratio Young's modulus Modulus of rigidity What is the unit of the modulus of elasticity? N-m Pa Unitless N-m/s The elastic deformation of a material is directly proportional to the cross sectional area inversely proportional to the length inversely proportional to the force inversely proportional to modulus of elasticity What is the ratio of the transverse strain to the corresponding axial strain of unaxial stress? Poisson's ration Euler's ration Dielectric index Refractive index The ratio of the lateral strain to the linear strain within elastic limit is known as Young's modulus Bulk modulus Modulus of rigidity Poisson's ratio Volumetric strain is the Change in volume per unit time Square root of difference of volume Original volume minus change in volume Ratio of change in volume to original volume Within elastic limit, the volumetric strain is proportional to the hydrostatic stress. Young's modulus Bulk modulus Modulus of rigidty Modulus of elasticity A curved member with a straight vertical leg is carrying a vertical load at Z. As shown in figure. The stress resultants in XY segment are Bending moment, shear force and axial force Bending moment and axial force only Bending moment and shear force only Axial force only The ratio of direct stress to volumetric strain subjected to 3D stresses, is equal to Young's mudulus Bulk modulus Modulus of rigidity Modulus of elasticity What is another term for modulus of rigidity? Shear modulus Modulus of elasticity Young's modulus Bulk modulus Within elastic limit, the shear stress is proportional to shear strain. What is called? Modulus of elasticity Young's elasticity Bulk modulus Modulus of rigidity The ratio between tensile stress and tensile strain or compressive stress and compressive strain is termed as Bulk modulus of elasticity Modulus elasticity Modulus of rigidity None of these When the beam is subjected to transverse shearing force, the shear stress in the upper fiber will be: Minimum Maximum Zero Depends on other data Strength of materials can be describes as "statics of deformable_____bodies" Elastic Rigid Compressible Thermal The material having same elastic properties in all directions are called Isotropic materials Uniform materials Piratical materials Ideal materials A bar of varying square cross-section is loaded symetrically as shown in the figure. Loads shown are placed on one of the axes of symmetrical cross-section. Ignoring self weight, the maximum tensile stress in N/mm2 anywhere is 32.0 30.0 25.0 14.0 Tensile and compressive stress are caused by forces____to the areas on which they act Perpendicular Paralled Angled None of these Stress on an object is_____its cross sectional area greater than less than directly proportional to inversely proportional to Measured mechanical properties of materials are same in a particular direction at each point. This property of the material is known as Isotropy Homogeneity Orthotropy Anisotropy One Newton per square meter is one Joule Watt Pascal Kelvin What is the unit of strain? Pascal Unitless N-m N-m/s The intensity of stress which causes unit strain is called___ Unit mass Modulus of Rigidity Bulk modulus Modulus of elasticity A material obeys Hooke's law up to Limit of propornality Yield point Plastic limit Elastic limit

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