300+ REAL TIME Strength of Materials Objective Questions & Answers 2023

250+ TOP MCQs on Deflection of Simply Supported and Answers

This set of Strength of Materials Multiple Choice Questions on “Deflection of Simply Supported”.

1. __________ of a beam is a measure of its resistance against deflection.
a) Strength
b) Stiffness
c) Slope
d) Maximum bending
Answer: b
Clarification: The ratio of maximum deflection of a beam to its corresponding span is termed as the stiffness of the beam. It is the measure of resistance against the deflection.

2. The maximum induced ___________ stresses should be within the safe permissible stresses to ensure strength of the beam.
a) Tensile
b) Compressive
c) Bending
d) Lateral
Answer: c
Clarification: A beam is said to be strengthy when the maximum induced bending and shear stresses are within the safe permissible stresses of the beam material.

3. Elastic line is also called as ___________
a) Deflection curve
b) Plastic curve
c) Linear curve
d) Hooke’s curve
Answer: a
Clarification: The deflection curve is defined as the line to which the longitudinal axis of a beam deflects or bends under given load. This curve is also known as elastic line or elastic axis.

4. In simply supported beams, the slope is _____________ at supports.
a) Minimum
b) Zero
c) Maximum
d) Uniform
Answer: c
Clarification: The slope at any section in the deflected beam is defined as the angle developed in radians which the tangent at the section makes with the actual axis of the proposed beam. In simply supported beams, the slope is maximum at the supports.

5. In simply supported beam deflection is maximum at ____________
a) Midspan
b) Supports
c) Point of loading
d) Through out
Answer: a
Clarification: In simply supported beams, deflection is maximum at the mid span of a symmetrically loaded beam.

6. Calculate the maximum deflection of a simply supported beam if the maximum slope at A is 0.0075 radians and the distance of centre of gravity of bending moment diagram to support A is 1.33 metres.
a) 9.975 mm
b) 9.5 mm
c) 9.25 mm
d) 9.785 mm
Answer: a
Clarification: The deflection occurs at support A = A/EI = 0.0075 radians
Maximum deflection = Ax/EI = 0.0075 × 1.33
y = 9.975 mm.

7. ____________ is the best example for accelerator (admixture).
a) Sulphonated formaldehyde
b) Calcium chloride
c) Sulphonated naphthalene
d) Polyglycolesters
Answer: b
Clarification: Calcium chloride is more widely used as an accelerator. By adding two percent (2%) of the weight of cacl2 admixture to the Portland cement the Maximum strength is attained within 1-3 days.

8. _____________ is used to reduce the time for hardening of concrete.
a) Accelerators
b) Super plasticizer
c) Retarder
d) Air entraining admixture
Answer: c
Clarification: The admixtures (retarders) are generally used to reduce the time for hardening of concrete. They are used in situations like:
i. In hot weather condition, a tendency towards false set is corrected
ii. When concrete is to be placed in difficult positions.

9. Full form of LEED ________
a) Leadership in Energy and Efficiency Development
b) Leadership in Environmental and Energy Design
c) Leadership in Energy and Environmental Design
d) Leadership in Efflorescence and Energy Demand
Answer: c
Clarification: LEED stands for Leadership in Energy and Environmental Design. The fly ash is environmentally friendly solutions that meet or exceed performance specifications fly ash contributes a lot to LEED.

10. _____ has a lower heat of hydration.
a) Quarry dust
b) Fly ash
c) Ordinary Portland cement
d) Bulk sand
Answer: b
Clarification: The process that liberates heat when water is added to cement is known as heat of hydration. The process of hydration is not instantaneous. The fly ash is possessing lower heat of hydration.

11. The factors that influence rate of hydration is _________
a) The fineness of cement
b) Temperature of cement
c) Quality of water
d) Temperature of water
Answer: a
Clarification: The products of hydration are colloidal and increase the surface area of solid paste during hydration and the water is the main ingredient which reacts chemically. The rate of hydration is mainly influenced by temperature of cement.

12. The steel suits best to reinforcement with concrete.
a) False
b) True
Answer: b
Clarification: The Steel is be used for reinforcing a concrete for following properties:
i. Steel is about 30 times stronger in compression and 300 times stronger intention compared to concrete.
ii. It develops good bond with concrete
iii. It is highly fire resistant.

13. The average crushing strength of precast concrete blocks as per CAI is __________
a) 4.5 N/mm²
b) 5 N/mm²
c) 3.5 N/mm²
d) 4 N/mm²
Answer: c
Clarification: Hollow concrete blocks are used in load bearing walls. In the manufacture of these blocks, the light height aggregates are used. The recommended size is 39 × 19 × 30 cm.
The average crushing strength of blocks Shall be 5N/mm².

14. A simply supported beam of span as shown in the figure is subjected to a concentrated load w at its metre span and also to a uniformly distributed load equality w what is the total diffraction it its midpoint.
a) 18 Wl³ /384 EI
b) 13 Wl³/ 384 EI
c) 5 Wl³/ 384 EI
d) 18 Wl³/ 384 EI
Answer: b
Clarification: The total deflection at midpoint of a simply supported beam is

y = 5Wl³/ 384 EI + Wl³/ 48 EI
y = 13Wl³/ 384 EI.

15. Meander ratio is the ratio of meander belt to __________
a) Meander depth
b) Meander width
c) Meander length
d) Meander cross-section
Answer: c
Clarification: When a river departs from its straight course and follows a sinuous winding path, the river is said to be meandering. Meander ratio is the ratio of meander belt to the meander length.

250+ TOP MCQs on Tensile Stress and Answers

Strength of Materials Multiple Choice Questions on “Tensile Stress”.

1. During a tensile test on a ductile material ____________
a) Nominal stress at fracture is higher than the ultimate stress
b) True stress at fracture is higher than the ultimate stress
c) True stress a fracture is the same as the ultimate stress
d) None of the mentioned
Answer: b
Clarification: In a ductile material, the true stress at fracture will be higher the ultimate stress.

2. When equal and opposite forces applied to a body, tend to elongate it, the stress so produced, is called ____________
a) Shear stress
b) Compressive stress
c) Tensile stress
d) Transverse stress
Answer: c
Clarification: When subjected to two equal and opposite pulls as a result of which there is an increase in length. This produces tensile stress.

3. Which of the following stresses are associated with the tightening of a nut on a bolt?
P. Tensile stress due to the streching of bolt
Q. Bending stress due to the bending of bolt
R. Torsional shear stress due to frictional resistance between the nut and the bolt
Select the correct answer using the codes given below.
a) P and Q
b) P and R
c) Only p
d) R and Q
Answer: a
Clarification: Bending stress comes when there is some kind of eccentric load. When nut is tightened, the bolt will pull itself and stretching will be there resulting in the tensile stress. Torsional stress will come when the nut is rotating.

4. In a tensile test, near the elastic limit zone ____________
a) Tensile stress increases in linear proportion to the stress
b) Tensile stress increases at a faster rate
c) Tensile stress decreases at a faster rate
d) None of the mentioned
Answer: c
Clarification: The stress first decreases and then decreases before the strain hardening occurs. The decreases in the stress is due to the attraction between carbon molecules.

5. Match the following and give the correct code given in options:

List 1	List 2
A. Tensile test on CI	1. Plain fracture on a transverse plane
B. Tensile test on MS	2. Granular helecoidal fracture
C. Torsion test on CI	3. Cup and cone
	4. Granular fracture in a transverse plane

a) A – 1 B – 2 C – 4
b) A – 1 B – 4 C – 2
c) A – 3 B – 1 C – 2
d) A – 3 B – 4 C – 1
Answer: d
Clarification: Tensile test on CI is done on cup and cone. Torsion test on MS is on plain fracture on a traverse plane.

6. The phenomenon of slow growth of strain under a steady tensile stress is called ____________
a) Yielding
b) Creeping
c) Breaking
d) None of the mentioned
Answer: b
Clarification: Creeping is the phenomenon of slow growing strain under a stress for a period of time.

7. A rod 150cm long and of diameter 2cm is subjected to an axial pull of 20kN. What will be the stress?
a) 60 N/mm²
b) 65 N/mm²
c) 63.6 N/mm²
d) 71.2 N/mm²
Answer: c
Clarification: The stress = load / area
Load = 20,000N
Area = π/4 (20)2 = 100π mm².

8. The stress in a rod is 70 N/mm² and the modulus of elasticity is 2 x 10⁵ N/mm². what will be the strain in the rod?
a) 0.00052
b) 0.00035
c) 0.00030
d) 0.00047
Answer: b
Clarification: As E = σ/e
Here, E = 2 * 10⁵ N/mm²
And, σ = 70 N/mm²
e = 70/2*10⁵ = 0.00035.

9. What will be the minimum diameter of a steel wire, which is used to raise a load of 4000N if the stress in the rod is not to exceed 95 MN/m²?
a) 6mm
b) 6.4mm
c) 7mm
d) 7.3mm
Answer: d
Clarification: As stress = load / area
Area = load/stress
Also, area is π/4 D2 so π/4 D2 = 4000 / 95
And D = 7.32.

10. A tensile test was conducted on mild steel bar. The load at elastic limit was 250kN and the diameter of the steel bar was 3cm. What will be the value of stress?
a) 35368 x 10⁴ N/m²
b) 32463 x 10⁴ N/m²
c) 35625 x 10⁴ N/m²
d) 37562 x 10⁴ N/m²
Answer: a
Clarification: The stress = load / area
Load = 150 x 1000N
Area = π/4 (0.03)² m2.

250+ TOP MCQs on Moment of Inertia of Section and Answers

This set of Strength of Materials Problems on “Moment of Inertia of Section”.

1. What is the moment of inertia of a circular section?
a) πD⁴/64
b) πD³/32
c) πD³/64
d) πD⁴/32
Answer: a
Clarification: The moment of inertia of a circular section is πD⁴/64.

2. What is the moment of inertia of a rectangular section about an horizontal axis through C.G?
a) bd³/6
b) bd²/12
c) b²d²/12
d) bd³/12
Answer: d
Clarification: The moment of inertia of a rectangular section about an horizontal axis through C.G is bd³/12.

3. What is the moment of inertia of a rectangular section about an horizontal axis passing through base?
a) bd³/12
b) bd³/6
c) bd³/3
d) bd²/3
Answer: c
Clarification: The moment of inertia of a rectangular section about an horizontal axis passing through base is bd³/3.

4. What is the moment of inertia of a triangular section about the base?
a) bh²/12
b) bh³/12
c) bh³/6
d) bh²/6
Answer: b
Clarification: The moment of inertia of a triangular section about the base is bh³/12.

5. What is the moment of inertia of a triangular section about an axis passing through C.G. and parallel to the base?
a) bh³/12
b) bh³/24
c) bh³/36
d) bh³/6
Answer: c
Clarification: The moment of inertia of a triangular section about an axis passing through C.G. and parallel to the base is bh³/36.

6. What will be the moment of inertia of a circle in cm4 of diameter is 10cm?
a) a340
b) 410
c) 460
d) 490
Answer: d
Clarification: The moment of inertia of a circle is = πD⁴/64
= 491.07 cm⁴.

7. What will be the moment of inertia of the given rectangle about an horizontal axis passing through the base?

a) 1500 mm⁴
b) 1650 mm⁴
c) 1666 mm⁴
d) 1782 mm⁴
Answer: c
Clarification: The moment of inertia of a rectangular section about an horizontal axis passing through base = bd³/3
= 5x10x10x10/3
= 1666.66 mm⁴.

8. What will be the moment of inertia of the given rectangular section about an horizontal axis through C.G.?

a) 350 mm⁴
b) 379mm⁴
c) 416mm⁴
d) 500mm⁴
Answer: c
Clarification: The moment of inertia of a rectangular section about an horizontal axis through C.G = bd³/12
= 5x10x10x10/12
= 416.67 mm⁴.

9. What will be the moment of inertia of the given triangle about the base?

a) 20.33 mm⁴
b) 21.33 mm⁴
c) 24.33 mm⁴
d) 22.33 mm⁴
Answer: b
Clarification: The moment of inertia of a triangular section about the base = bh³/12.
= 4x4x4x4/12
= 21.33 mm⁴.

10. What will be the moment of inertia of the given triangle about an axis passing through C.G and parallel to base?

a) 6.1 mm⁴
b) 7.1 mm⁴
c) 8.1 mm⁴
d) 7.56 mm⁴
Answer: b
Clarification: The moment of inertia of a triangular section about an axis passing through C.G. and parallel to the base = bh³/36.
= 4x4x4x4/36
= 7.11 mm⁴.

11. What will be the difference between MOI of two triangle sections is in 1st, MOI is taken about its base and in 2nd MOI is taken about its centroid?
a) bh³/12
b) bh³/18
c) bh³/36
d) bh³/24
Answer: b
Clarification: The moment of inertia of a triangular section about the base is bh³/12
The moment of inertia of a triangular section about an axis passing through C.G. is bh³/36
So the difference = bh³/12 – bh³/36 = bh³/18.

Strength of Materials Problems,

250+ TOP MCQs on Maximum Shear Stress – 1 and Answers

This set of Strength of Materials Multiple Choice Questions on “Maximum Shear Stress – 1”.

1. Shear stress at top most fibre of rectangular section is _____________
a) Maximum
b) Minimum
c) Zero
d) Uniform through out
Answer: c
Clarification: In rectangular section,
The shear stress at a distance “y “ from NA = 6F/bd³ × u (u = d²/4-y)
The maximum shear stress occurs at a neutral axis, in the above equation when y is equal to zero. q is max. Hence the shear stress topmost fibre of rectangular section is zero.

2. 1 GPA = ____________ pa.
a) 10⁵
b) 10⁶
c) 10⁸
d) 10⁹
Answer: d
Clarification: 1 Giga Pascal is equal to 10⁹N/m²(Pascal)
In the same way 1 kilo Pascal equal to 10³ pascals
1 mega Pascal is equal to 106 pascals.

3. The maximum shear stress in an I section is __________
a) F/8I ×[B/b (D²-d²)+d²]
b) F/6I ×[B/b (D²-d²)+d²]
c) F/8I ×[B/b (D³-d³)+d²]
d) F/4I ×[B/b (D²-d²)+d²]
Answer: a
Clarification: Shear stress at top flange of the I section is zero.
Shear stress at the junction of web and flange= B/b ×F/8I (D²-d²).
Shear stress at bottom of the flange = F/8I (D²-d²).
And shear force is maximum at neutral axis i.e F/8I ×[B/b (D²-d²)+d²].

4. Find the modulus of section of square beam of size 150 × 150 mm?

a) 654.5m³
b) 550.85m³
c) 562.5m³
d) 586.9m³
Answer: c
Clarification: Here, a = side of a square section = 150 mm.
Moment of inertia for square section = a⁴/12; y=a/2.
Section modulus Z = I/y = a³/6 = 150³/6 = 562.5 ×10³ mm³.

5. In steel sections, the junction between a flange and web is known as ________
a) Edge
b) Fillet
c) Corner
d) Lug
Answer: b
Clarification: In a steel section, the junction between the flange and the web is known as fillet. The connections solve issues of complex geometry for joining the members of a central hub while they provide the standard connection through out. They are not readily available.

6. The percentage of carbon in structural steel is __________
a) 0.2 – 0.27 %
b) 0.6 – 0.85 %
c) 0.7 – 1.23 %
d) 1.23 – 1.45%
Answer: a
Clarification: The percentage of carbon in structural steel is 0. 2 to 0.27. Percentage of the carbon in steel increases the ductility of the Steel decreases.

7. The minimum percentage elongation for mild steel is __________
a) 6%
b) 13%
c) 23%
d) 34%
Answer: c
Clarification: The minimum percentage elongation for mild steel is 23% and the tensile strength of steel is usually taken as 42 to 54 kg/mm².

8. GOST standards are used in _________
a) Italy
b) Poland
c) Russia
d) Pakistan
Answer: c
Clarification: GOST is an acronym for gosudastvennyy standard used in Russia.
It usually carries two part number, one indicates serial number and other indicates the year of issue
For example; GOST 155-70.

9. The allowable tensile stresses in steel structures is taken as 1500 kg /cm2 to ______
a) 1765 kg /cm²
b) 1900 kg /cm²
c) 2125 kg /cm²
d) 2455 kg/cm²
Answer: c
Clarification: Steel structures are available in various sections such as rolled I beams, channels, angle iron, bars, flat plates etc. The allowable tensile stress in steel structures is 1500 kg /cm² to 2125 kg /cm².

10. As per IS:800, the minimum thickness of web should not be less than ______
a) d/250
b) d/300
c) d/350
d) d/125
Answer: a
Clarification: As per IS: 800, the minimum thickness of web should not be less than d/250; [Where d = clear distance between Flange angles]. In case of unstiffened web, the minimum thickness of web plate should not be less than d/85.

11. The failing of a very long column is initially by ___________
a) Crushing
b) Collapsing
c) Buckling
d) Twisting
Answer: c
Clarification: The members considerably long in comparison of lateral dimensions are called Long columns. The members essentially fail by buckling (or) crippling to bending. According to Euler’s formula the long column can be determined.

12. What is the allowable stress in cast iron?
a) 3200 N/mm²
b) 2400 N/mm²
c) 3400 N/mm²
d) 5500 N/mm²
Answer: d
Clarification: The allowable stress in cast iron is 5500 N/mm².

Position	Stress (N/mm²)	Rankine’s Constant
Mild steel	3200	1/7500
Wrought iron	2500	1/9000
Cast iron	5500	1/1600

13. Modulus of resilience is defined as __________
a) Resilience at ultimate stress
b) Resilience per unit volume
c) Resilience at proportional limit
d) Resilience at elastic limit
Answer: b
Clarification: The resilience per unit volume is defined as modulus of resilience. It is a property of the material. The Modulus of resilience is equal to 1Mpa for Steel with the proportionality limit of 200 Mpa.

14. A spring used to absorb shocks and vibrations is called as _______
a) Conical spring
b) Leaf spring
c) Disc spring
d) Torsion spring
Answer: b
Clarification: A leaf spring used to absorb shocks and vibrations and the springs in brakes and clutches are invariably used in order to apply forces.

15. A rectangular beam of 500 mm wide is subjected to maximum shear force of 250kN, the corresponding maximum shear stress been 3 N/mm². The depth of the beam is equal to ______

a) 200mm
b) 250mm
c) 300mm
d) 350mm
Answer: b
Clarification: The maximum shear force in a rectangular section is 3N/mm².
In rectangular sections; Maximum shear force = 3/2 ×[F/bd]
& 3 = 3/2 ×[250 ×10³/ 500 × d]
d = 250mm.

250+ TOP MCQs on Analyse Slope of Various Beams and Answers

This set of Strength of Materials Questions and Answers for Entrance exams on “Analyse Slope of Various beams”.

1. A cantilever beam subjected to a point load at free end of span “l” m and possess flexural rigidity (EI).
a) Wl³ / 6EI
b) Wl⁴/ 8EI
c) Wl²/ 2EI
d) Wl⁴/ 5EI
Answer: c
Clarification: Area of BMD = A = Wl²/ 2.
According to Mohr’s theorem 1, slope (i) = A/EI = Wl²/ 2EI radians.

2. Cantilever scaffolding is also known as ____________
a) mason’s scaffolding
b) suspended scaffolding
c) needle scaffolding
d) ladder scaffolding
Answer: c
Clarification: The cantilever scaffolding consists of platform supported by series of cantilever beams passing through window openings. They are used when it is not possible to fix the standards into the ground. It is also known as needle scaffolding.

3. Scaffolding you generally adopted when the height of structure is above ___________
a) 1.3 m
b) 1.5 m
c) 1.7 m
d) 2.2 m
Answer: b
Clarification: Scaffolding is a temporary platform provided with necessary supports close to the work to provide a limited space for the labours and workers for the construction of masonry work of any structure above 1.5 m.

4. The horizontal platform in between any two flights of a staircase is called ___________
a) Landing
b) Balustrade
c) Nosing
d) Stringer
Answer: a
Clarification: Landing in stair may be defined as the horizontal platform provided in between any two flights landing. Landing which provides 90 degree turn in the layout of a stair is known as quarter space landing.

5. The ratio of maximum load to the unit area is ________
a) Ultimate bearing capacity
b) Allowable bearing capacity
c) Safe bearing capacity
d) Bearing capacity
Answer: d
Clarification: The term bearing capacity of the soil is defined as the maximum load per unit area which the soil will resist safely without yielding or displacement.

6. ______ is part of a structure which transmits the load to the soil underneath.
a) Basement
b) Plinth
c) Lentils
d) Foundation
Answer: d
Clarification: The lowest artificial built part of structure which transmits the load of the structure to the soil lying underneath. The foundation of a structure is always constructed below ground level. They distribute the load of structure over large bearing area. It increases the stability of the structure as a whole.

7. Full form of NBC ___________
a) Nominal Building Centre
b) National Building Code
c) National Building Cluster
d) Nominal Buoyance Centre
Answer: b
Clarification: NBC stands for National Building Code. According to NBC, all the buildings existing and in construction are classified into number of groups. The respective crystal details are followed with respective synapses.

8. The ultimate bearing capacity/factor of safety = ____________
a) Bearing capacity
b) Allowance bearing capacity
c) Safe bearing capacity
d) Soil consolidation capacity
Answer: c
Clarification: The safe bearing capacity of the soil is equal to ultimate bearing capacity divided by certain factor of safety. Roughly a factor of safety of 2 is used for most of the building sites and generally, a factor of safety of 2.5 to 3 is considered for heavy building constructions.

9. _____ is measured on percentage basis.
a) Camber
b) Formation width
c) Super elevation
d) Shoulder
Answer: a
Clarification: The rise given to the centre of the carriage way with reference to its edge can be termed as camber. It is expressed as 1 vertical to n horizontal. It is also measured along percentage basis.

10. ______ bridge any opening like a window, door, cupboard etc in a building.
a) Sunshade
b) Lintel
c) Footings
d) Stairs
Answer: b
Clarification: Lintel is a horizontal structural member spanning any opening to support loads of the structure coming over it.
i) To facilitate the fixing of doors and windows frames wherever.
ii) They used to receive load from wall constructed over them.

11. The first solar cooker was developed in the year ____________
a) 1947
b) 1953
c) 1945
d) 1960
Answer: c
Clarification: The Solar cookers have a very relevant place in the present fuel consumption pattern. The first solar cooker was developed in the year 1945 by Mr M K Ghosh. The main reasons for non- acceptance of this device was a cheap availability of cooking fuel.

12. Solar arrays are defined in terms of ____________
a) Circuits
b) Diodes
c) Kernel
d) Panels
Answer: a
Clarification: The solar arrays are electrically defined in terms of circuits each of which contributes a portion of the total current output at some nominally specified array voltage.

13. In a cantilever of span “L” subjected to a concentrated load of “W” at a distance of L/3 from free end. The deflection is ________
a) WL³/3EI
b) 14WL³/81EI
c) WL³/81EI
d) 8WL³/81EI
Answer: d
Clarification: The deflection developed at the

y= W × ( 2L/3)³/ 3EI
y= 8WL³/81 EI.

14. Calculate the slope in a simply supported beam subjected to point load at centre. Take the EI into consideration.
a) Wl³/4EI
b) Wl²/16EI
c) Wl³/8EI
d) Wl⁴/6EI
Answer: b
Clarification: The slope in a beam can be determined by Mohr’s theorem 1: i = A/EI.
The BMD of beam portion will be Wl²/16.
The slope (i) = Wl²/16EI.

15. Which of the following is a mechanical property of materials?
a) Surface Tension
b) Compressibility
c) Elasticity
d) Specific volume
Answer: c
Clarification: The elasticity is the property by which the body returns to its original shape after the removal of external load. If a body regains completely its original shape is said to be a perfectly elastic material. Rubber, mild steel and copper may be considered to be perfectly elastic within certain limits.

Strength of Materials for Entrance exams,

250+ TOP MCQs on Compressive Stress and Answers

Strength of Materials Multiple Choice Questions on “Compressive Stress”.

1. For keeping the stress wholly compressive the load may be applied on a circular column anywhere within a concentric circle of diameter _____________
a) D/2
b) D/3
c) D/4
d) D/8
Answer: c
Clarification: The load application on a circular column affects stress. If it is under D/4 the stress will be wholly compressive.

2. Consider two bars A and B of same material tightly secured between two unyielding walls. Coefficient of thermal expansion of bar A is more than that of B. What are the stresses induced on increasing the temperature?
a) Tension in both the materials
b) Tension in material A and compression in material B
c) Compression in material A and tension in material B
d) Compression in both the materials
Answer:d
Clarification: Since both the supports are fixed and both bars will try to expand, so rise in temperature will cause compressive stresses in the bars.

3. What will be the unit of compressive stress?
a) N
b) N/mm
c) N/mm²
d) Nmm
Answer: c
Clarification: As the stress is the ratio of force to the area, so it will be N/mm². Here mm is normally used in its calculation most of the time.

4. A cast iron T section beam is subjected to pure bending. For maximum compressive stress to be 3 times the maximum tensile stress, centre of gravity of the section from flange side is ____________
a) h/2
b) H/3
c) H/4
d) 2/3h
Answer: c
Clarification: H/4 when the applied moment is sagging. Otherwise, I.e. if the applied moment is hogging it is H/4. as in the options both are not given means we have to take hogging.

5. A solid circular shaft of diameter d is subjected to a torque T. the maximum normal stress induced in the shaft is ____________
a) Zero
b) 16T/πd³
c) 32T/πd³
d) None of the mentioned
Answer: b
Clarification: The maximum torque transmitted by a circular solid shaft is obtained from the maximum shear stress induced at the outer surface of the solid shaft and given by T = πD³/16 x normal stress,
So, normal stress = 16T/πd³.

6. When a rectangular beam is loaded transversely, the maximum compressive stress develops on ____________
a) Bottom fibre
b) Top fibre
c) Neutral axis
d) Every cross-section
Answer: b
Clarification: Loaded means loaded downwards. In that case, upper fibres will be compressed while lower will be expanded. Hence maximum compressive stress will be developed in top layer.

7. An axial residual compressive stress due to a manufacturing process is present on the outer surface of a rotating shaft subjected to bending. Under a given bending load, the fatigue of the shaft in the presence of the residual compressive stress is ____________
a) Decreased
b) Increases or decreased, depending on the external bending load
c) Neither decreased nor increased
d) Increases
Answer: d
Clarification: From the Gerber’s parabola that is the characteristic curve of the fatigue life of the shaft in the presence of the residual compressive stress. The fatigue life of the material is effectively increased by the introduction of compressive mean stress, whether applied or residual.

8. A steel bar of 40mm x 40mm square cross-section is subjected to an axial compressive load of 200kN. If the length of the bar is 2m and E=200GPa, the elongation of the bar well be ____________
a) 1.25mm
b) 2.70mm
c) 4.05mm
d) 5.40mm
Answer: a
Clarification: Elongation of the bar = Pl/AE = -200x103x 2000 / ( 1600 x 200 x 103) = -1.25
The minus sign here shows that the stress here is compressive.