Theory Of Machine MCQ Questions & Answers

71

When a mass of a critically damped single degree of freedom system is deflected from its equilibrium position and released, then it will

A) Return to equilibrium position without oscillation B) Oscillate with increasing time period C) Oscillate with decreasing amplitude D) Oscillate with constant amplitude

Discuss

Answer & Solution

Answer: Option B

No explanation is given for this question. Let's Discuss on Board

72

In a reciprocating engine, usually __________ of the reciprocating masses are balanced.

A) One-half B) Two-third C) Three-fourth D) Whole

Discuss

Answer & Solution

Answer: Option B

No explanation is given for this question. Let's Discuss on Board

73

Which one of the following is an exact straight line mechanism using lower pairs?

A) Watt’s mechanism B) Grasshopper mechanism C) Robert’s mechanism D) Peaucellier’s mechanism

Discuss

Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board

74

If there are L number of links in a mechanism, then number of possible inversions is equal to

A) L + 1 B) L - 1 C) L D) L + 2

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

75

Cam size depends upon

A) Base circle B) Pitch circle C) Prime circle D) Outer circle

Discuss

Answer & Solution

Answer: Option A

No explanation is given for this question. Let's Discuss on Board

76

The example of spherical pair is

A) Bolt and nut B) Lead screw of a lathe C) Ball and socket joint D) Ball bearing and roller bearing

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

77

In a simple harmonic motion, the velocity vector with respect to displacement vector

A) Is in phase B) Leads by 90° C) Leads by 180° D) Lags by 90°

Discuss

Answer & Solution

Answer: Option B

Solution:

Simple Harmonic Motion (SHM) is like a swinging pendulum or a bouncing spring.
Imagine a point moving back and forth in a straight line.
Its position changes constantly, this is the displacement.
Its speed also changes constantly, this is the velocity.
In SHM, the acceleration is always directed towards the center point (equilibrium position) and is proportional to the displacement.

Now, let's think about the relationship between the velocity and displacement.
When the displacement is zero (at the center point), the velocity is at its maximum.
When the displacement is at its maximum (at the extremes of the motion), the velocity is zero.

This means that the velocity is not in step with the displacement; there's a difference of 90 degrees (or π/2 radians) between them.
The velocity vector leads the displacement vector by 90°. This is because the velocity reaches its peak a quarter of a cycle *before* the displacement reaches its peak.
Therefore, the correct option is B: Leads by 90°

78

In S.H.M., the velocity vector w.r.t. displacement vector

A) Leads by 90° B) Lags by 90° C) Leads by 180° D) Are in phase

Discuss

Answer & Solution

Answer: Option A

No explanation is given for this question. Let's Discuss on Board

79

For an isochronous Hartnell governor (where r₁ and r₂ = Maximum and minimum radius of rotation of balls respectively, S₁ and S₂ = Maximum and minimum force exerted on the sleeve respectively and M = Mass on the sleeve)

A) $$\frac{{{\text{mg}} + {{\text{S}}_1}}}{{{\text{mg}} + {{\text{S}}_2}}} = \frac{{{{\text{r}}_1}}}{{{{\text{r}}_2}}}$$ B) $$\frac{{{\text{mg}} - {{\text{S}}_1}}}{{{\text{mg}} - {{\text{S}}_2}}} = \frac{{{{\text{r}}_2}}}{{{{\text{r}}_1}}}$$ C) $$\frac{{{{\text{S}}_1}}}{{{{\text{S}}_2}}} = \frac{{{{\text{r}}_1}}}{{{{\text{r}}_2}}}$$ D) $$\frac{{{{\text{S}}_2}}}{{{{\text{S}}_1}}} = \frac{{{{\text{r}}_1}}}{{{{\text{r}}_2}}}$$

Discuss

Answer & Solution

Answer: Option A

No explanation is given for this question. Let's Discuss on Board

80

The effort of a Porter governor is equal to (where c = Percentage increase in speed, m = Mass of ball and M = Mass on the sleeve)

A) $${\text{c}}\left( {{\text{m}} - {\text{M}}} \right){\text{g}}$$ B) $${\text{c}}\left( {{\text{m}} + {\text{M}}} \right){\text{g}}$$ C) $$\frac{{\text{c}}}{{\left( {{\text{m}} + {\text{M}}} \right){\text{g}}}}$$ D) $$\frac{{\text{c}}}{{\left( {{\text{m}} - {\text{M}}} \right){\text{g}}}}$$

Discuss

Answer & Solution

Answer: Option B

No explanation is given for this question. Let's Discuss on Board

Theory Of Machine MCQ Questions & Answers | Mechanical Engineering