Theory Of Machine MCQ Questions & Answers

71

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

A) Sliding pair B) Rolling pair C) Surface pair D) Lower pair

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Answer & Solution

Answer: Option D

Solution:

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.

72

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)

A) $${\text{m}}{\omega ^2}{\text{r}}\sin \theta $$ B) $${\text{m}}{\omega ^2}{\text{r}}\cos \theta $$ C) $${\text{m}}{\omega ^2}{\text{r}}\frac{{\sin 2\theta }}{{\text{n}}}$$ D) $${\text{m}}{\omega ^2}{\text{r}}\frac{{\cos2\theta }}{{\text{n}}}$$

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Answer & Solution

Answer: Option B

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73

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)

A) $${\text{m}}{\omega ^2}{\text{r}}\sin \theta $$ B) $${\text{m}}{\omega ^2}{\text{r}}\cos \theta $$ C) $${\text{m}}{\omega ^2}{\text{r}}\frac{{\sin 2\theta }}{{\text{n}}}$$ D) $${\text{m}}{\omega ^2}{\text{r}}\frac{{\cos2\theta }}{{\text{n}}}$$

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Answer & Solution

Answer: Option D

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74

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)

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

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Answer & Solution

Answer: Option A

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75

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

A) Remains unaffected B) Decreases C) Increases D) None of these

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Answer & Solution

Answer: Option C

Solution:

For a given lift of the sleeve, the sensitiveness of the governor increases as the speed range decreases.

76

For S.H.M. cam, the acceleration of the follower at the ends of the stroke and aimed stroke respectively, is

A) Maximum and zero B) Zero and maximum C) Minimum and maximum D) Zero and minimum

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Answer & Solution

Answer: Option A

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77

Which of the below are inversions of slider crank mechanism?
1. Oscillating cylinder engine mechanism
2. Toggle mechanism
3. Radial cylinder engine mechanism
4. Quick return mechanism

A) 1, 2 and 4 B) 2, 3 and 4 C) 1, 2 and 3 D) 1, 3 and 4

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Answer & Solution

Answer: Option D

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78

The unbalanced force due to revolving masses

A) Varies in magnitude but constant in direction B) Varies in direction but constant in magnitude C) Varies in magnitude and direction both D) Constant in magnitude and direction both

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Answer & Solution

Answer: Option B

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79

The relative velocity of B with respect to A in a rigid link AB is

A) Parallel to AB B) Perpendicular to AB C) Along AB D) At 45° to AB

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Answer & Solution

Answer: Option B

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80

A shaft carrying three rotors will have

A) No node B) One node C) Two nodes D) Three nodes

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Answer & Solution

Answer: Option C

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Theory Of Machine MCQ Questions & Answers | Mechanical Engineering