Design of Machine Elements Objective Questions - Set 18 - ObjectiveBooks
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# Practice Test: Question Set - 18

1. The form factor of a helical gear __________ with the increase in the helix angle.
(A) Increases
(B) Decreases
(C) Remains constant
(D) None of these

2. For a bevel gear having the pitch angle θ, the ratio of formative number of teeth (TE) to actual number of teeth (T) is
(A) 1/sinθ
(B) 1/cosθ
(C) 1/tanθ
(D) sinθ cosθ

3. Which of the following has threads at both ends?
(A) Bolt
(B) Tap bolt
(C) Stud
(D) None of these

4. The connecting rod bolts are tightened up so that tightening stress
(A) Is just sufficient to hold parts together
(B) Approaches yield point
(C) Is 50% of yield point
(D) Is about yield point divided by safety factor

5. The circumferential and longitudinal strains in a cylindrical boiler under internal steam pressure are εc and εl respectively. The change in volume of the boiler cylinder per unit volume will be
(A) εc + 2εl
(B) 2εc + εl
(C) εc + εl²
(D) εc² + εl

6. The material used for brake lining should have __________ coefficient of friction.
(A) Low
(B) High
(C) Moderate
(D) None of these

7. 18/8 steel contains
(A) 18% nickel and 8% chromium
(B) 18% chromium and 8% nickel
(C) 18% nickel and 8% vanadium
(D) 18% vanadium and 8% nickel

8. Which of the following spring is used in mechanical wrist watch?
(A) Helical compression spring
(B) Spiral spring
(C) Torsion spring
(D) Belleville spring

9. The effective stress in wire ropes during normal working is equal to the stress due to
(A) Axial load plus stress due to bending
(B) Acceleration/retardation of masses plus stress due to bending
(C) Axial load plus stress due to acceleration/retardation
(D) Bending plus stress due to acceleration/retardation

10. In levers, leverage is the ratio of
(A) Load lifted to the effort applied
(B) Mechanical advantage to the velocity ratio
(C) Load arm to the effort arm
(D) Effort arm to the load arm

11. A special case of ductility which permits materials to be rolled or hammered into thin sheets, is called
(A) Plasticity
(B) Elasticity
(C) Ductility
(D) Malleability

12. Wahl's stress factor __________ very rapidly as the spring index decreases.
(A) Increases
(B) Decreases
(C) Remain same
(D) None of these

13. When an open coiled helical compression spring is subjected to an axial compressive load, the maximum shear stress induced in the wire is (where D = Mean diameter of the spring coil, d = Diameter of the spring wire, K = Wahl's stress factor, and W = Axial compressive load on the spring)
(A) (WD/ πd3) × K
(B) (2WD/ πd3) × K
(C) (4WD/ πd3) × K
(D) (8WD/ πd3) × K

14. The face of the tooth is the
(A) Surface of the top of the tooth
(B) Surface of the tooth above the pitch surface
(C) Surface of the tooth below the pitch surface
(D) Width of the tooth measured along the pitch circle

15. In a marine flange coupling, the pitch circle diameter of bolts is taken as
(A) 1.2 d
(B) 1.6 d
(C) 2 d
(D) 2.5 d

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