SECTION-4

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

##### Q71. If the balance weight placed diametrically opposite to the crank at crank radius (r) is cW, then unbalanced force normal the line of stroke of the reciprocating engine, is equal to

$\text { (a) } \frac{C W}{g} \omega^{2} r \cos \theta$
$\text { (b) }(1-c) \frac{W}{g} \omega^{2} r \cos \theta$
$\text { (c) } \frac{c W}{g} \omega^{2} r \sin \theta$
$\text { (d) }(1-c) \frac{W}{g} \omega^{2} r \sin \theta .$

$\text { (c) } \frac{c W}{g} \omega^{2} r \sin \theta$

##### Q72. If the ratio of the length of connecting rod to the crank radius is very large, then

(a) primary forces are negligible
(b) primary forces are maximum
(c) secondary forces are negligible
(d) secondary forces are maximum.

Ans:  (c) secondary forces are negligible

##### Q73. In locomotives, with two cylinders, the cranks of two cylinders are placed at right angles to each other in order to

(a) start the locomotive in any position
(b) reduce the effect of secondary forces
(c) reduced the effect of primary forces
(d) (a) and (b) only.

Ans: (d) (a) and (b) only.

##### Q74. The swaying couple and variation in the tractive effort is due to

(a) primary disturbing force
(b) secondary disturbing force
(c) both (a) and (b)
(d) none of the above

Ans: (c) both (a) and (b)

##### Q75. If the balance weight placed diametrically opposite to the crank at crank radius (r) is cW, then unbalanced force along the line of stroke of the reciprocating engine, is equal to

$\text { (a) } \frac{C W}{g} \omega^{2} r \cos \theta$

$\text { (b) }(1-c) \frac{W}{g} \omega^{2} r \cos \theta$

$\text { (c) } \frac{c W}{g} \omega^{2} r \sin \theta$

$\text { (d) }(1-c) \frac{W}{g} \omega^{2} r \sin \theta .$

Ans: $\text { (b) }(1-c) \frac{W}{g} \omega^{2} r \cos \theta$

##### Q76. The secondary disturbing force due to inertia of reciprocating parts of an engine is equal to the centrifugal produced by the equivalent crank

(a) having an equivalent radius of$\frac{r^{2}}{4 l}$

(b) running at twice the speed
(c) having a weight attached to its end
(d) all of the above

Ans : (d) all of the above

##### Q77. If a weight equal to the weights of reciprocating parts is attached diametrically opposite to crank at crank radius, then

(a) primary disturbing force is completely balanced
(b) primary disturbing force is not balanced
(c) primary disturbing force is completely balanced but an unbalanced vertical force is introduced
(d) none of the above.

Ans: (c) primary disturbing force is completely balanced but an unbalanced vertical force is introduced

##### Q78. The primary forces are balanced partially. The balance weight placed diametrically opposite to the crank is cW, where W is the weight of reciprocating parts. The usual value of c for locomotive is

(a) one-fourth
(b) one-half
(c) one-third
(d) two-thirds.

Ans:  (d) two-thirds.

##### Q79. The number of cycles of motion completed in a unit interval of time is known as

(a) period
(b) frequency
(c) resonance
(d) damping.

Ans: (b) frequency

##### Q80. The time taken, by a vibrating body to complete one cycle, is known as

(a) period
(b) frequency
(c) resonance
(d) damping.

Ans: (a) period

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##### 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