This set of Strength of Materials Questions and Answers for Experienced people focuses on “Strength of Section due to Section Modulus”.
1. The moment which resists the external bending is called ______
a) Moment of shear
b) Tolerating moment
c) Moment of resistance
d) Maximum bending moment
View Answer
Explanation: The tensile and compressive stresses developed in the beam section from a couple whose moment is equal to the external bending moment. The moment of this couple which resists the external bending is known as moment of resistance [MR].
2. ______ strength is caused by a moment of resistance offered by a section.
a) Shear
b) Flexural
c) Axial
d) Longitudinal
View Answer
Explanation: The moment of couple with resists action of bending moment is a moment of resistance and the flexural strength possessed by section is the moment of resistance offered by it.
3. A Steel rod 200 mm diameter is to be bent into a circular arc section. Find radius of curvature. Take f = 120N/mm2 & E = 2×105 N/mm2.
a) 134m
b) 166m
c) 162m
d) 174m
View Answer
Explanation: Diameter of Steel rod = 200mm; y = d/2 = 100mm.
f= 120N/mm2.
E= 2×105N/mm2.
By flexural equation we have f/y = E/R
R = 2×105/ 120 ×100
= 166.6m.
4. The hoop stress is also known as ______
a) Parametrical stress
b) Surface stress
c) Circumferential stress
d) Lateral stress
View Answer
Explanation: The stress which is developed in the walls of the cylinder due to internal fluid pressure and which acts tangential to the circumference is called hoop stress or circumferential stress.
Total pressure = p × A.
5. The ____ of strongest beam that can be cut out of a circular section of diameter D.
a) Load
b) Size
c) material
d) cross section
View Answer
Explanation: The size of the strongest Beam that can be cut out of a circular section of diameter D is
Depth;
d = Square root of 2/3b = D / square root of 3.
Among the given sections for the same depth I section gives maximum strength.
6. The moment resisting capacity of the cross section of a beam is termed as ______ of the beam.
a) Stiffness
b) Strength
c) Modulus
d) Inertia
View Answer
Explanation: The moment resisting capacity of the cross section of a beam is termed as the strength of the beam. The bending stress is maximum at the extreme fibres of the cross section. The strength of the two beams of same material can be compared by the sectional modulus values.
7. Find the moment of resistance of rectangular beam off grid to 40 mm depth 400 mm if the bending stress is 15 N/mm2.
a) 78 kNm
b) 84 kNm
c) 96 kNm
d) 132 kNm
View Answer
Explanation: Moment of resistance (MR) = Z × f
= bd2 / 6 × 15
= 96 ×106 Nmm.
8. A rectangular beam 100 mm wide is subjected to a maximum shear force and 50 kN. Find the depth of the beam.
a) 350 mm
b) 185 mm
c) 200 mm
d) 250 mm
View Answer
Explanation: Let the depth of the beam be d
Maximum shear stress = 3/2 (Average Shear stress)
d= 3×5000/ 3×2×100.
9. What is the approximate value of coefficient of linear expansion for steel?
a) 13 × 10-66 /°C
b) 11.5 × 10-6 /°C
c) 12 × 10-6 /°C
d) 16 × 10-6 /°C
View Answer
Explanation: The increase in length of body per unit rise of temperature in original name is termed as coefficient of linear expansion and it is denoted by Greek letter alpha. Coefficient of linear expansion for steel is 11.5 × 10-6 /°C. For copper it is 17 × 10-6 /°C.
10. A hollow shaft has outside diameter 120 mm and thickness 20 mm. Find the polar moment of inertia (J).
a) 16.36 × 106 mm4
b) 14.65 × 106 mm4
c) 10.32 × 106 mm4
d) 23.18 × 106 mm4
View Answer
Explanation: D = 120mm
t= 20mm & d = D – 2t = 80mm.
Polar moment of inertia (J) is π/32 ×[ D4– d4].
π/32 × [ 1204– 804 ].
16.36 × 106 mm4.
Sanfoundry Global Education & Learning Series – Strength of Materials.
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