SECTION-3

###### MACHINE DESIGN MCQ

Q21. The Wahl’s stress factor is equal to

(a) 4C- 1/4C-4+ 0.615/C
(b) C- 1/C-4+ 0.615/C
(c)  4C- 1/C-4+ 0.615/C
(d) C- 1/4C-4+ 0.615/C
where C = Spring index.

Ans:(a) 4C- 1/4C-4+ 0.615/C

##### Q22. A closely coiled helical spring is made out of 1 cm diameter steel rod. The spring carries an axial pull of 20 kg. The coil consists of 10 complete turns with a mean radius of 5 cm. If modulus of rigidity of spring material is 8 × 105 kg/cm2, the maximum shear stress induced in the section of the rod would be

(a) 3200/π   kg/cm2
(b) 1600/π   kg/cm2
(c) 800/π     kg/cm2
(d) 400/π     kg/cm2

Ans:(d) 400/π     kg/cm2.

(a) 2 cm
(b) 1 cm
(c) 0.5 cm
(d) 0.4 cm.

Ans:(a) 2 cm

##### Q24. A closely coiled helical spring is made out of 1 cm diameter steel rod. The spring carries an axial pull of 20 kg. The coil consists of 10 complete turns with a mean radius of 5 cm. If modulus of rigidity of spring material is 8 × 105 kg/cm2, stiffness of the spring would be

(a) 20 kg per cm
(b) 15 kg per cm
(c) 10 kg per cm
(d) 8 kg per cm.

Ans:(b) 15 kg per cm

##### Q25. In an open-coiled helical spring, the maximum shear stress induced in a wire of circular section taking into consideration the effect of direct shear stress and effect of curvature of the wire, is equal to

(a) 8WD/πd3
(b) 8WD/πd3× K
(c) 16WD/πd3× K
(d) 8W/πD2× K.
where W = Applied axial load, D = Mean diameter of coils,
d = Diameter of spring wire, and K = Wahl’s shear stress factor.

Ans:(b) 8WD/πd3× K

##### Q26. In a helical spring if the pitch angle is more than 10° and spring is subjected to an axial compressive load, the stresses induced in the wire would be

(a) compressive
(b) shear
(c) bending
(d) (b) and (c) only.

Ans:(d) (b) and (c) only.

##### Q27. In close-coiled helical spring, the maximum shear stress induced in a wire of the circular section is equal to

(a) 16WD/πd3
(b)  8WD/πd3
(c)  4WD/πd3
(d) 32WD/πd3
where W = Applied load, D = Mean diameter of coils, and
d = Diameter of spring wire.

Ans:(b) 8WD/πd3

##### Q28. In a close-coiled helical spring, the deflection of spring coils is equal to

(a) 16WD3 n/Cd4
(b) 32WD3 n/Cd4
(c)  8WD3 n/Cd4
(d) 4WD3 n/Cd4
where C = Modulus of rigidity, and n = Number of effective coils.

Ans:(a)16WD3 n/Cd4

##### Q29. Socket joint is mostly used for pipes which

(a) carry steam at high pressure
(b) carry water at low pressure
(c) are burried in the earth
(d) carry fluid at high pressure.

Ans:(b) carry water at low pressure

##### Q30. Expansion joints are mostly used for pipes which

(a) carry steam at high pressure
(b) carry water at low pressure
(c) are burried in the earth
(d) carry fluid at high pressure.

Ans:(a) carry steam at high pressure

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##### Read More Sections of Machine Design

Each section contains maximum 80 Questions. To practice more questions visit other sections.

Machine Design MCQ – Section-1

Machine Design MCQ – Section-2

Machine Design MCQ – Section-3

Machine Design MCQ – Section-4

Machine Design MCQ – Section-5

Machine Design MCQ – Section-6

Machine Design MCQ – Section-7