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.

**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/cm^{2}

(b) 1600/π kg/cm^{2}

(c) 800/π kg/cm^{2}

(d) 400/π kg/cm^{2}.

**Q23. 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 ×105kg/cm**^{2}, the deflection of the spring would be

^{2}, the deflection of the spring would be

(a) 2 cm

(b) 1 cm

(c) 0.5 cm

(d) 0.4 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.

**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/πd^{3}

(b) 8WD/πd^{3}× K

(c) 16WD/πd^{3}× K

(d) 8W/πD^{2}× K.

where W = Applied axial load, D = Mean diameter of coils,

d = Diameter of spring wire, and K = Wahl’s shear stress factor.

**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.

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

(a) 16WD/πd^{3}

(b) 8WD/πd^{3}

(c) 4WD/πd^{3}

(d) 32WD/πd^{3}

where W = Applied load, D = Mean diameter of coils, and

d = Diameter of spring wire.

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

(a) 16WD^{3} n/Cd^{4}

(b) 32WD^{3} n/Cd^{4}

(c) 8WD^{3} n/Cd^{4}

(d) 4WD^{3} n/Cd^{4}

where C = Modulus of rigidity, and n = Number of effective coils.

**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.

**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.

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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**