Engineering Questions with Answers - Multiple Choice Questions

# Strength of Materials MCQs Strength of Section due to Section Modulus

1 - Question

The moment which resists the external bending is called ______
a) Moment of shear
b) Tolerating moment
c) Moment of resistance
d) Maximum bending moment

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 - Question

______ strength is caused by a moment of resistance offered by a section.
a) Shear
b) Flexural
c) Axial
d) Longitudinal

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 - Question

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

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 - Question

The hoop stress is also known as ______
a) Parametrical stress
b) Surface stress
c) Circumferential stress
d) Lateral stress

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 - Question

The ____ of strongest beam that can be cut out of a circular section of diameter D.
b) Size
c) material
d) cross section

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 2/3
b = D / square root of 3.
Among the given sections for the same depth I section gives maximum strength.

6 - Question

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

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 - Question

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

Explanation: Moment of resistance (MR) = Z × f
= bd2 / 6 × 15
= 96 ×106 Nmm.

8 - Question

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

Explanation: Let the depth of the beam be d
Maximum shear stress = 3/2 (Average Shear stress)
d= 3×5000/ 3×2×100.

9 - Question

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

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 - Question

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

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.

11 - Question

Strength of Materials MCQs Bending Stress in Unsymmetrical Sections

Unsymmetrical bending occurs due to ______
a) The Beam cross section is unsymmetrical
b) The shear Centre does not coincide with the neutral axis
c) The Beam is subjected to trust in addition to bending moment
d) The bending moment diagram is unsymmetrical

Explanation: If the bending moment diagram of a beam seems to unsymmetrical, then with respect to that diagram, the bending is said to be unsymmetrical bending.

12 - Question

A body having similar properties throughout its volume is said to be _____________
a) Isotropic
b) Homogeneous
c) Continuous
d) Uniform

Explanation: A body having similar properties throughout its volume is said to be “homogeneous” and the material which exhibits the same elastic properties in all directions is called “isotropic”.

13 - Question

Principal plane has ____________
a) Maximum shear stress
b) Maximum tensile stress
c) Zero shear stress
d) Minimum bending stress

Explanation: Principal stress is a magnitude of direct stress, across a principal plane which is a particular plane having no shear stress at all.

14 - Question

Calculate the Strain energy that can be stored in a body to be pulled with 100 N/mm2 stress (f) and E = 2×105 N/mm2.
a) 0.9 kNm
b) 0.05kNm
c) 0.87kNm
d) 0.54kNm

Explanation: Strain energy stored in the body be “U” = f2/ 2 E × Volume.
= 1002/ 2×2×105
= 0.05 kNm.

15 - Question

Materials exhibiting time bound behaviour are known as _______
a) Isentropic
b) Reactive
c) Fissile
d) Visco elastic

Explanation: Materials exhibiting time bound behaviour popularly known as visco elastic and if a body having similar properties throughout its volume it is known as homogeneous and according to one assumption, the concrete is considered to be homogeneous material.

16 - Question

What are the units of true strain?
a) Kg/m2
b) Kg/ m3
c) No dimensions
d) N/mm

Explanation: As we know strain is the ratio of change in dimension to the original dimension. It is denoted by “e”. Metres/metres hence no dimensions.

17 - Question

Revert size is generally expressed in terms of _______
a) Shank width
b) Girder length
c) Lap length
d) Shank diameter

Explanation: Rivets are ductile metal pins of often used for joining structure members as in case of trusses, stanchions plate girders, cylindrical shells etc. The distance between two heads is known as shank and rivet size is generally expressed in terms of shank diameter.

18 - Question

________ joints are necessary to keep a structure safe against shrinkage.
a) Construction
b) Functional
c) Transverse
d) Longitudinal

Explanation: Functional joints are necessary to keep the structures safe against shrinkage, expansion sliding and warping of concrete. These types of joints are made by forming continuous breaks in large continuous areas of structures at suitable distance apart. The joints or breaks may be 6 to 38 mm wide.

19 - Question

The specific gravity of sand is __________
a) 2.8
b) 2.25
c) 3.2
d) 2.65

Explanation: The specific gravity of sand is 2.65.

 Materials Specific gravity Trap 2.9 Gravel 2.66 Granite 2.8 Sand 2.65

20 - Question

To what radius a silver strip 200 mm wide and 40 mm thick can be bent if the maximum stress in the ship is 80 N/mm2. Young’s modulus for Silver is 80×103 N/mm2.
a) 20m
b) 30m
c) 15m
d) 35m

Explanation: Here, b = 200 mm; d = 40mm
y = 40/2 = 20 mm
f = 80N/mm2
From the relation; E/R = f/y
R = E×y / f
= 80000×20 / 80
= 20000mm = 20m.

21 - Question

In flitched beams ______ remains same for both materials.
a) Stress
b) Strain
c) Section modulus
d) Young’s modulus

Explanation: Due to bending, the strain will be same in both the materials. A timber beam strengthened by steel strips.
Where E of timber / E of steel = m
The equivalent width = b + 2mt.

22 - Question

What is the moment due to dead load in case of continuous beams at the middle of interior spans?
a) w L3 / 12
b) w L2/ 14
c) w 3/ 20
d) w L2 / 24

Explanation: The moment due to dead load in case of continuous beams at the middle of interior spans is w L2 /24

 Position Moment due to dead load Near middle of end span W L2/ 12 At the middle of interior span W L2/ 24 At the support next to and support -W L2/ 22

23 - Question

A continuous beam is one which is _______
a) Infinitely long
b) Supported at two points
c) Supported it more than two supports
d) Supported by a prop

Explanation: A beam which is supported by more than two supports is known as a continuous beam. In this beam, bending moment is low and hence the deflection in the beam is also comparatively less. This beam is stiffer when compared to the other traditional beams.

24 - Question

The effective length of column depends upon ________
a) the cross section of beam
b) end conditions
c) maximum bending moment
d) extreme fibres

Explanation: The effective length of column depends upon end conditions.

 End condition Effective length Both ends hinged L Both ends fixed L/2 One end is fixed and other end free 2L

25 - Question

The phenomenon under which the strain of material varies under constant stress is known as ________
a) Creep
b) Hysteresis
c) Viscoelasticity
d) Strain hardening

Explanation: A creep is a plastic deformation underweight the strain of material where is under constant stress this is one of the mechanical properties of the engineering materials. The best example is the failure of concrete.

26 - Question

Volumetric strain = 3× _____ strain.
a) Lateral
b) Linear
c) Composite
d) Yield

Explanation: eV (volumetric strain) = 3× linear strain = 3×e
The volumetric strain is algebraic sum of all the linear(or) axial strain when a solid to be subjected to equal normal sources of the same type of all faces we will have €x, €y and €z equal in value. In this case the volumetric strain will be 3 times the linear strain in any of the three axes.

27 - Question

The stress corresponding to breaking point is known as _____________
a) yield stress
b) ultimate stress
c) breaking stress
d) normal stress

Explanation: After reaching ultimate stress, the stress strain curve suddenly falls with rapid increase in strain and specimen breaks. The stress corresponding to breaking point is known as breaking stress and it is denoted by G.

28 - Question

Determine the yield stress of a steel rod 20 mm diameter, if the yield load on the steel rod is 88kN.
a) 240.55 N/mm2
b) 280.25 N/mm2
c) 325 N/mm2
d) 290.45 N/mm2

Explanation: Initial area of the Steel rod of 20 mm = 314 mm2 [area of circle] Yield stress = yield load/ Area
= 88 × 103/ 314
= 280.25 N/mm2.

29 - Question

What is the elongation percentage of a steel rod of 50 mm diameter if the total extension is is 54 mm and gauge length is 200 mm.
a) 27%
b) 23%
c) 43%
d) 35%

Explanation: Percentage elongation = Total extension / Gauge length × 100
= 54/200 × 100
= 27%.

30 - Question

__________ joints are provided when there is a break in the concreting operation.
a) transverse joints
b) longitudinal joints
c) construction joints
d) warpage joints