Questions and answers for exam Preparation

MCQs

Total Questions : 543 | Page 1 of 55 pages

Question 1. The lower pairs are _________ pairs.

Self-closed
Force-closed
Friction closed
None of these

Discuss Question

Answer: Option A. -> Self-closed

Question 2. In considering friction of a V-thread, the virtual coefficient of friction (μ1) is given by

μ1 = μsinβ
μ1 = μcosβ
$${\mu _1} = \frac{\mu }{{\sin \beta }}$$
$${\mu _1} = \frac{\mu }{{\cos \beta }}$$

Discuss Question

Answer: Option D. -> $${\mu _1} = \frac{\mu }{{\cos \beta }}$$

Question 3. In a coupling rod of a locomotive, each of the four pairs is a ________ pair.

Sliding
Turning
Rolling
Screw

Discuss Question

Answer: Option B. -> Turning

Question 4. A kinematic chain is known as a mechanism when

None of the links is fixed
One of the links is fixed
Two of the links are fixed
None of these

Discuss Question

Answer: Option B. -> One of the links is fixed

Question 5. A pantograph is a mechanism with

Lower pairs
Higher pairs
Rolling pairs
Turning pairs

Discuss Question

Answer: Option A. -> Lower pairs

Question 6. If two moving elements have surface contact in motion, such pair is known as

Sliding pair
Rolling pair
Surface pair
Lower pair

Discuss Question

Answer: Option D. -> Lower pair
When two elements of a pair have a surface contact when relative motion takes place and the surface of one element slides over the surface of the other, the pair formed is known as lower pair.

Question 7. The primary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, $$\omega $$ = Angular speed of crank, r = Radius of crank, $$\theta $$ = Angle of inclination of crank with the line of stroke and n = Ratio of the length of connecting rod to radius of crank)

$${\text{m}}{\omega ^2}{\text{r}}\sin \theta $$
$${\text{m}}{\omega ^2}{\text{r}}\cos \theta $$
$${\text{m}}{\omega ^2}{\text{r}}\frac{{\sin 2\theta }}{{\text{n}}}$$
$${\text{m}}{\omega ^2}{\text{r}}\frac{{\cos2\theta }}{{\text{n}}}$$

Discuss Question

Answer: Option B. -> $${\text{m}}{\omega ^2}{\text{r}}\cos \theta $$

Question 8. The secondary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, $$\omega $$ = Angular speed of crank, r = Radius of crank, $$\theta $$ = Angle of inclination of crank with the line of stroke and n = Ratio of the length of connecting rod to radius of crank)

$${\text{m}}{\omega ^2}{\text{r}}\sin \theta $$
$${\text{m}}{\omega ^2}{\text{r}}\cos \theta $$
$${\text{m}}{\omega ^2}{\text{r}}\frac{{\sin 2\theta }}{{\text{n}}}$$
$${\text{m}}{\omega ^2}{\text{r}}\frac{{\cos2\theta }}{{\text{n}}}$$

Discuss Question

Answer: Option D. -> $${\text{m}}{\omega ^2}{\text{r}}\frac{{\cos2\theta }}{{\text{n}}}$$

Question 9. The sensitiveness of the governor __________ as the speed range decreases.

Remains unaffected
Decreases
Increases
None of these

Discuss Question

Answer: Option C. -> Increases
For a given lift of the sleeve, the sensitiveness of the governor increases as the speed range decreases.

Question 10. The velocity of piston in a reciprocating steam engine is given by (where $$\omega $$ = Angular velocity of crank, r = Radius of crank pin circle, $$\theta $$ = Angle turned by crank from inner dead center and n = Ratio of length of connecting rod to the radius of crank)

$$\omega {\text{r}}\left( {\sin \theta + \frac{{\sin 2\theta }}{{\text{n}}}} \right)$$
$$\omega {\text{r}}\left( {\cos\theta + \frac{{\cos2\theta }}{{\text{n}}}} \right)$$
$${\omega ^2}{\text{r}}\left( {\sin \theta + \frac{{\sin 2\theta }}{{\text{n}}}} \right)$$
$${\omega ^2}{\text{r}}\left( {\cos\theta + \frac{{\cos2\theta }}{{\text{n}}}} \right)$$

Discuss Question

Answer: Option A. -> $$\omega {\text{r}}\left( {\sin \theta + \frac{{\sin 2\theta }}{{\text{n}}}} \right)$$