SECTION-6

#### Theory of Machine objective type questions/Multiple choice questions

##### Q41. Choose the correct statement

(a) If the angle of inclined plane is less than the friction angle, the arrangement is known as self-locking.
(b) The efficiency of a square threaded screw is maximum when the helix angle of the screw is equal to 45° minus half of friction angle.
(c) Self-locking is a desired property of a machine.
(d) All the above.

Ans: (d) All the above.

##### Q42. Which one is a correct statement ?

(a) The rubbing surface in case of pivot and collar bearing is always flat.
(b) The rubbing surface in case of pivot and collar bearing is always conical.
(c) The rubbing surface in case of pivot bearing is flat and in case of collar bearing it is conical.
(d) The rubbing surface in case of pivot bearing is either flat or conical but in case of collar bearing it is generally flat.

Ans: (d) The rubbing surface in case of pivot bearing is either flat or conical but in case of collar bearing it is generally flat.

##### Q43. In case of flat pivot bearing, the rubbing velocity is

(a) maximum at the centre of the contact area
(b) zero at the centre and maximum at the outer radius
(c) uniform throughout the contact area
(d) zero at the outer radius.

Ans:  (b) zero at the centre and maximum at the outer radius

##### Q44. The rate of wearing in case of flat pivot bearing is

(a) inversely proportional to the rubbing velocity
(b) directly proportional to the pressure intensity
(c) directly proportional to the rubbing velocity
(d) both (b) and (c).

Ans: (d) both (b) and (c).

##### Q45. For uniform pressure the ratio of the frictional torque for a flat collar bearing to the frictional torque for a conical collar bearing, is equal to

(a) 1.33
(b) 1.0
(c) sin θ
(d) cos θ
where θ = Semi-angle of the cone.

Ans: (c) sin θ

(a) 1.33
(b) 1.0
(c) sin θ
(d) cos θ

Ans: (c) sin θ

##### Q47. The frictional torque transmitted by a conical collar bearing is

(a) less than that of flat collar bearing
(b) equal to that of flat collar bearing
(c) more than that of flat collar bearing
(d) none of the above.

Ans: (c) more than that of flat collar bearing

##### Q48. The effect of slip on velocity ratio of the belt is to

(a) increase the velocity ratio
(b) decrease the velocity ratio
(c) keep the velocity ratio constant
(d) none of the above.

Ans: (b) decrease the velocity ratio

##### Q49. The addendum as compared to dedendum of a toothed gear wheel is

(a) more
(b) less
(c) same
(d) can be more or less.

Ans:  (b) less

##### Q50. In a simple trains of three wheels, the third wheel will rotate

(a) in the opposite direction to the first wheel
(b) in the same direction as the first wheel
(c) in any direction
(d) none of the above.

Ans:  (b) in the same direction as the first wheel

DEAR READERS IF YOU FIND ANY ERROR/TYPING MISTAKE PLEASE LET ME KNOW IN THE COMMENT SECTIONS OR E-MAIL: [email protected]

##### Read More Sections of Theory of Machine Objective Questions

Each section contains maximum 80 Questions. To practice more questions visit other sections.

Theory of Machine MCQ – Section-1

Theory of Machine MCQ – Section-2

Theory of Machine MCQ – Section-3

Theory of Machine MCQ – Section-4

Theory of Machine MCQ – Section-5

Theory of Machine MCQ – Section-6