When inertia of gearing is taken into consideration, then an additional shaft must be introduced in the equivalent system of the rotors connected by the shaft.

A torsional system with discs of moment of inertia $${I_1}$$ and $${I_2}$$ as shown in the below figure, is gear driven such that the ratio of speed of shaft B to shaft A is 'G'. Neglecting the inertia of gears, the equivalent inertia of disc on shaft B at the speed of shaft A is equal to
Theory of Machine mcq question image

A

$${\text{G}} \times {I_2}$$

B

$${{\text{G}}^2} \times {I_2}$$

C

$$\frac{{{I_2}}}{{\text{G}}}$$

D

$$\frac{{{I_2}}}{{{{\text{G}}^2}}}$$

In a gearing system, pump speed is one third of the motor. Shaft from motor is 6 cm in diameter and 30cm long, the impellar shaft is 10cm diameter and 60cm long. Mass moment of inertia is 1500 Kg-m2, C = 80Gn/m2. Neglecting the inertia of shaft and gears calculate the frequency of free torsional vibrations in Hz.

A

4.7

B

5.7

C

4.5

D

5.5

For a gearing system, the equivalent system is made consisting of two rotors. How many nodes will this new equivalent system will have?

A

0

B

1

C

2

D

3

For a gearing system, the equivalent system is made consisting of three rotors. How many nodes will this new equivalent system will have?

A

0

B

1

C

2

D

3

Which of the following is/are appropriate care and maintenance of centrifuges? I. Proper balancing of centrifuge tubes. II. Avoid long time exposure of the rotors to alkaline solution and acidic buffers. III. Cleaning centrifuges and rotors with coarse brushes and then wash them with distilled or de-ionized water after every run. IV. For overnight storage, the rotors are left upside down and then positioned in a safe and dry place.

A

I, II, III only

B

II, III and IV only

C

I, II, and IV only

D

II only

When inertia of gearing is taken into consideration, then which of the following should be taken into account.

A

Addition of rotor

B

Addition of gear

C

Addition of shaft

D

Addition of pump

A single cylinder oil engine works with a three rotor system, the shaft length is 2.5m and 70mm in diameter, the middle rotor is at a distance 1.5m from one end. Calculate the free torsional vibration frequency for a single node system in Hz if the mass moment of inertia of rotors in Kg-m2 are: 0.15, 0.3 and 0.09. C=84 kN/mm2

A

171

B

181

C

191

D

201

A single cylinder oil engine works with a three rotor system, the shaft length is 2.5m and 70mm in diameter, the middle rotor is at a distance 1.5m from one end. Calculate the free torsional vibration frequency for a two node system in Hz if the mass moment of inertia of rotors in Kg-m2 are: 0.15, 0.3 and 0.09. C=84 kN/mm2

A

257

B

281

C

197

D

277

Two heavy rotating masses are connected by shafts of lengths $${l_1},\,{l_2}$$ and $${l_3}$$ and the corresponding diameters are d₁, d₂ and d₃. This system is reduced to a torsionally equivalent system having uniform diameter d = d₁ of the shaft. The equivalent length of the shaft is

A

$$\frac{{{l_1} + {l_2} + {l_3}}}{3}$$

B

$${l_1} + {l_2}{\left( {\frac{{{{\text{d}}_1}}}{{{{\text{d}}_2}}}} \right)^3} + {l_3}{\left( {\frac{{{{\text{d}}_1}}}{{{{\text{d}}_3}}}} \right)^3}$$

C

$${l_1} + {l_2}{\left( {\frac{{{{\text{d}}_1}}}{{{{\text{d}}_2}}}} \right)^4} + {l_3}{\left( {\frac{{{{\text{d}}_1}}}{{{{\text{d}}_3}}}} \right)^4}$$

D

$${l_1} + {l_2} + {l_3}$$

A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the maximum speed of the intermediate shaft if the driving shaft has a constant speed of 500 r.p.m.

A

532.1 r.p.m

B

469.85 r.p.m

C

566.25 r.p.m

D

441.5 r.p.m.

When inertia of gearing is taken into consideration, then an additional shaft must be introduced in the equivalent system of the rotors connected by the shaft.

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