FACTOR OF SAFETY MULTIPLE CHOICE QUESTIONS (MCQ) WITH ANSWERS
FACTOR OF SAFETY
MULTIPLE CHOICE QUESTIONS
(MCQ) WITH ANSWERS
MCQ on factor of safety increases
understanding and clarity. Factor of
safety is extremely important in design of
machine elements. Factor safety takes care
of the uncertainties of all types.
Uncertainties are due to type of load,
the manner of load application and
amount of eccentricity encountered.
Fig. Factor of safety
Sr. No. 
Type of equipment 
Factor of safety 
1. 
Aircraft components 
1.5 to 2.5 
2. 
Boilers, Pressure vessels 
3.5 to 6 
3. 
Turbine rotating components 
2 to 3 
4. 
Turbine static components 
6 to 8 
5. 
Structural sheet work in buildings 
4 to 6 
6. 
Structural components in bridges 
5 to 7 
.7 
Bolts, ropes and hooks 
8 to 9 
8. 
Cast iron wheels 
20 
9. 
Heavy duty shafts 
10 to 12 
1. Factor of safety used under gradually applied load.
(a) 2 and 4
(b) 4 and 8
(c) 8 and 16
(d) None
(Ans: a)
2. Factor of safety used under suddenly applied load.
(a) 2 and 4
(b) 4 and 8
(c) 8 and 16
(d) None
(Ans: b)
3. Factor of safety under impact load is
(a) 2 and 4
(b) 4 and 8
(c) 8 and 16
(d) None
(Ans: c)
4. Safety factor for a ductile material is
(a) Real stress/unit stress
(b) Ultimate stress/maximum stress
(c) Yield stress/ allowable stress
(d) None
(Ans: c)
5. Factor of safety for a brittle material is
(a) Real stress/unit stress
(b) Ultimate stress/allowable stress
(c) Allowable stress/ Yield stress
(d) None
(Ans: b)
6. Factor of safety accounts for
(a) Uncertainties
(b) Linear displacements
(c) Parabolic displacements
(d) None
(Ans: a)
7. Other common name of the factor of safety is
(a) Strength factor
(b)Strain factor
(c)Ignorance factor
(d) None
(Ans: c)
8. Under exact analysis of stresses, factor of safety is
(a) More
(b) Less
(c) Zero
(d) None
(Ans: c)
9. Material cost due to high factor of safety
(a) Increases
(b) Decreases
(c) No change
(d) None
(Ans: a)
10. Which elastic theory of failure considers the factor of safety for a brittle material?
(a) Maximum principal stress theory
(b) Maximum shear stress theory
(c) Von Mises theory
(d) None
(Ans: d)
11. Which theory of elastic failure accounts for factor of safety for a ductile material?
(a) Maximum principal stress theory
(b) Maximum shear stress theory
(c) Maximum principal strain theory
(d) None
(Ans: b)
12. The factor of safety for a ductile material is
(a) σ_{yp}/σ_{allow}
(b) σ_{ult}/σ_{allow}
(c) σ_{ult}/σ_{yp}
_{(d) None}
Ans:(a)
13. Factor of safety in a ductile material is

Design stress/working stress

Ultimate stress / allowable stress

Yield stress/allowable stress

None
(Ans: c)
14. In a brittle material, factor of safety is

Design stress/working stress

Ultimate stress / allowable stress

Yield stress/allowable stress

None
(Ans: b)
15. Which theory of elastic failure considers the factor of safety for ductile material?

Principal Stress Theory

Shear Stress Theory

Principal Strain Theory

None
(Ans: b)
16. Which theory of elastic failure considers factor of safety for brittle material?

Maximum Principal Stress Theory

Shear Stress Theory (Maximum)

Maximum Shear Strain Energy Theory

None
(Ans: a)
17. Large value of factor of safety is
(a) Very good
(b) Good
(c) Bad
(d) None
(Ans: c)
18. What is the FOS for a domestic gas cylinder?
(a) 2 to 4
(b)4 to 6
(c) 6 to 8
(d) None
ANS: (b)
19. What is the factor of safety for a nut?
(a) 3 to 5
(b) 5 to 7
(c) 8 to 9
(d) None
ANS: (c)
20. The factor of safety for a flywheel is
(a) 5
(b) 10
(c) 15
(d) None
ANS: (d)
21. The factor of safety for a flywheel is
(a) 20
(b) 300
(c) 40
(d) None
ANS: (a)