Machine Design MCQ
SET-5
81. When a shaft is subjected to combined twisting moment (T) and bending moment (M), then the equivalent twisting moment is equal to
Answer: B
82. In helical gears, the right hand helixes on one gear will mesh __________ helixes on the other gear.
- A. right hand
- B. left hand
Answer: B
83. A connecting rod is designed as a
- A. long column
- B. short column
- C. strut
- D. all of these
84. The cross-section of the arm of a bell crank lever is
- A. rectangular
- B. elliptical
- C. I-section
- D. any one of these
Answer: D
85. The rocker arms in internal combustion engines are of first type levers.
- A. Correct
- B. Incorrect
Answer: A
86. In a crossed belt drive, the shafts are arranged parallel and rotate in the same directions.
- A. Correct
- B. Incorrect
Answer: B
87. In worm gears, the angle between the tangent to the pitch helix and an element of the cylinder, is known as
- A. helix angle
- B. pressure angle
- C. pitch lead angle
- D. none of these
Answer: A
88. Idler pulley is used for
- A. increasing velocity ratio
- B. for applying tension
- C. changing the direction of motion of belt
- D. all of these
Answer: B
89. The bell crank levers used in railway signalling arrangement are of third type levers.
- A. True
- B. False
Answer: B
90. When spring index increases, the value of Wahl’s stress factor
- A. increases linearly
- B. decreases linearly
- C. remains same
- D. increases exponentially
Answer: D
91. A shaft is subjected to a maximum bending stress of 80 N/mm2 and maximum shearing stress equal to 30 N/mm2 at a particular section. If the yield point in tension of the material is 280 N/mm2 and the maximum shear stress theory of failure is used, then the factor of safety obtained will be
- A. 2.5
- B. 2.8
- C. 3.0
- D. 3.5
Answer: B
92. The longitudinal stress is __________ of the circumferential stress.
- A. one-half
- B. two-third
- C. three-fourth
- D. double
Answer: A
93. The expression 0.175 – 0.841/T is the Lewis form factor for
- A. 2°composite and full depth involute system
- B. 20° full depth involute system
- C. 20° stub system
- D. none of the above
Answer: C
94. A screw will be self locking, if
- A. friction angle is less than helix angle
- B. friction angle is more than helix angle
- C. friction angle is equal to helix angle
- D. efficiency of screw is 100%
Answer: B
95. The maximum shear stress theory is used for
- A. brittle materials
- B. ductile materials
- C. plastic materials
- D. non-ferrous materials
Answer: B
96. The elasticity is the property of a material which enables it to
- A. regain its original shape after deformation when the external forces are removed
- B. draw into wires by the application of a tensile force
- C. resist fracture due to high impact loads
- D. retain deformation produced under load permanently
Answer: A
97. The surface finish factor for a mirror polished material is
- A. 0.45
- B. 0.65
- C. 0.85
- D. 1
Answer: D
98. For low and moderate speed engines, the cam follower should move with
- A. uniform velocity
- B. simple harmonic motion
- C. uniform accleration and retardation
- D. cycloidal motion
Answer: B
99. Which of the following statement is correct ?
- A. A parallel sunk key is a taperless key
- B. A parallel sunk key may be rectangular or square in cross-section
- C. A flat saddle key is a taper key which fits in a key way of the hub and is flat on the shaft
- D. all of the above
Answer: D
100. When a bolt and nut is made of mild steel, then the effective height of nut is made equal to (where d = Nominal diameter of bolt)
- A. 0.5 d
- B. 0.75 d
- C. d
- D. 1.25 d
Answer: C