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.