Mechanical Engineering Theory of Machines problems - Set 20 - ObjectiveBooks

# Practice Test: Question Set - 20

1. In S.H.M., the velocity vector w.r.t. displacement vector
(B) Lags by 90°
(D) Are in phase

2. In a steam engine, the distance by which the outer edge of the D-slide valve overlaps the steam port is called
(B) Steam lap
(C) Exhaust lap
(D) None of these

3. The natural frequency of free torsional vibrations of a shaft is equal to (where q = Torsional stiffness of the shaft, and I = Mass moment of inertia of the disc attached at the end of a shaft)
(A) 2π. √(q/I)
(B) 2π qI
(C) (1/2π). √(q/I)
(D) 1/2π

4. A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotor separately, are 100 Hz and 200 Hz respectively. The lowest critical speed is
(A) 5,367 r.p.m.
(B) 6,000 r.p.m.
(C) 9,360 r.p.m.
(D) 12,000 r.p.m.

5. The angle of inclination of the plane, at which the body begins to move down the plane is called
(A) Angle of friction
(B) Angle of repose
(C) Angle of projection
(D) None of these

6. Angle of descent of cam is defined as the angle
(A) During which the follower returns to its initial position
(B) Of rotation of the cam for a definite displacement of the follower
(C) Through which the cam rotates during the period in which the follower remains in the highest position
(D) Moved by the cam from the instant the follower begins to rise, till it reaches its highest position

7. The velocity of the rubbing surface __________ with the distance from the axis of the bearing.
(A) Increases
(B) Decreases
(C) Remain same
(D) None of these

8. A shaft carrying two rotors at its ends will have
(A) No node
(B) One node
(C) Two nodes
(D) Three nodes

9. When the two elements of a pair have __________ when in motion, it is said to a lower pair.
(A) Line or point contact
(B) Surface contact
(C) Body contact
(D) None of these

10. The natural frequency of free transverse vibrations due to uniformly distributed load acting over a simply supported shaft is (where δS = Static deflection of simply supported shaft due to uniformly distributed load)
(A) 0.4985/ √δS
(B) 0.5615/ √δS
(C) 0.571/ √δS
(D) 0.6253/ √δS

11. The load cup of a screw jack is made separate from the head of the spindle to
(A) Enhance the load carrying capacity of the jack
(B) Reduce the effort needed for lifting the working load
(C) Reduce the value of frictional torque required to be countered for lifting the load
(D) Prevent the rotation of load being lifted

12. Any point on a link connecting double slider crank chain will trace a
(A) Straight line
(B) Circle
(C) Ellipse
(D) Parabola

13. In elliptical trammels
(A) All four pairs are turning
(B) Three pairs turning and one pair sliding
(C) Two pairs turning and two pairs sliding
(D) One pair turning and three pairs sliding

14. A chain comprises of 5 links having 5 joints. Is it kinematic chain?
(A) Yes
(B) No
(C) It is a marginal case
(D) Data are insufficient to determine it

15. In a circular arc cam with roller follower, the acceleration in any position of the lift will depend only upon
(A) Total lift, total angle of lift, minimum radius of cam and cam speed
(B) Radius of circular arc, cam speed, location of centre of circular arc and roller diameter
(C) Mass of cam follower linkage, spring stiffness and cam speed
(D) Total lift, centre of gravity of the cam and cam speed

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