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.