Mechanical Machine Design Questions and Answers - Set 27 - ObjectiveBooks

# Practice Test: Question Set - 27

1. During hot working of metals,
(A) Porosity of the metal is largely eliminated
(B) Grain structure of the metal is refined
(C) Mechanical properties are improved due of refinement of grains
(D) All of the above

(A) Equal to
(B) Less than
(C) Greater than
(D) None of these

3. For circumferential joint in boilers, the type of joint used is
(A) Butt joint with single cover plate
(B) Butt joint with double cover plate
(C) Lap joint with one ring overlapping the other
(D) Any one of the above

4. The efficiency of a riveted joint is equal to
(A) Pt /P
(B) Ps /P
(C) Pc /P
(D) Least of Pt, Ps and Pc/P

5. If a shaft made from ductile material is subjected to combined bending and twisting moment, calculations based on which one of the following failure theories will give the most conservative value?
(A) Maximum principal stress theory
(B) Maximum shear stress theory
(C) Maximum strain energy theory
(D) Maximum distortion energy theory

6. An elastic bar is fixed at the upper end and loaded at the lower end by a falling weight. The shock load produced can be reduced by
(A) Increasing the length of bar
(B) Decreasing the cross-sectional area of the bar
(C) Decreasing the modulus of elasticity of the bar
(D) All of the above

7. A localized compressive stress at the area of contact between two members is known as
(A) Tensile stress
(B) Bending stress
(C) Bearing stress
(D) Shear stress

8. According to I.B.R., shearing resistance required to shear off the rivet per pitch length (in double shear) is (where n = Number of rivets per pitch length)
(A) (π/4)× τ × n
(B) 1.875 × (π/4) × τ × n
(C) 2 × (π/4) × τ × n
(D) 3 × (π/4)× τ × n

9. 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

10. The initial tension (in newtons) in a bolt used for making a fluid tight joint like steam engine cover joints, is calculated by the relation (where d = Nominal diameter of bolt in mm)
(A) 1420 d
(B) 1680 d
(C) 2080 d
(D) 2840 d

11. A connecting rod should be
(A) Strong in buckling about X-axis
(B) Strong in buckling about Y-axis
(C) Equally strong in buckling about X-axis and Y-axis
(D) Any one of the above

12. Two shafts of the same length and material are joined in series. If the ratio of their diameters is 2, then the ratio of their angles of twist will be
(A) 2
(B) 4
(C) 8
(D) 16

13. A steel containing 0.8% carbon is known as
(A) Eutectoid steel
(B) Hypereutectoid steel
(C) Hypo-eutectoid steel
(D) None of these

14. Creep in belt is due to
(A) Material of the belt
(B) Material of the pulley
(C) Uneven extensions and contractions due to varying tension
(D) All of the above

15. Stress concentration factor is defined as the ratio of
(A) Maximum stress to the endurance limit
(B) Nominal stress to the endurance limit
(C) Maximum stress to the nominal stress
(D) Nominal stress to the maximum stress

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