# Dynamics of Machinery (3151911) MCQ

### MCQs of Balancing of Reciprocating Masses

MCQ No - 1

#### When the crank is at the inner dead center, in a reciprocating steam engine, then the velocity of the piston will be

(A)

minimum

(B)

zero

(C)

maximum

(D)

none of the mentioned

B
MCQ No - 2

#### The unbalanced primary forces in a reciprocating engine are

(A)

balanced completely

(B)

balanced partially

(C)

balanced by secondary forces

(D)

not balanced

B
MCQ No - 3

(A)

True

(B)

False

B
MCQ No - 4

#### The acceleration of piston in a reciprocating steam engine is given by (where ω = Angular velocity of the crank, r = Radius of crank pin circle, θ = Angle turned by the crank from inner dead center and n = Ratio of length of connecting rod to the radius of the crank)

(A)

$$\omega.r\;\left(\sin\;\theta+\frac{\sin\;2\theta}n\right)$$

(B)

$$\omega.r\;\left(\cos\;\theta+\frac{\cos\;2\theta}n\right)$$

(C)

$$\omega^2.r\;\left(\sin\;\theta+\frac{\sin\;2\theta}n\right)$$

(D)

$$\omega^2.r\;\left(\cos\;\theta+\frac{\cos\;2\theta}n\right)$$

D
MCQ No - 5

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

(A)

$$mr\omega^2\;\sin\theta$$

(B)

$$mr\omega^2\;\cos\theta$$

(C)

$$mr\omega^2\left(\frac{\sin\;2\theta}n\right)$$

(D)

$$mr\omega^2\left(\frac{\cos\;2\theta}n\right)$$

B