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<br> <img src="/images/question-image/mechanical-engineering/theory-of-machine/1528355323-41.JPG" title="Theory of Machine mcq question image" alt="Theory of Machine mcq question image">

An electric motor drives a machine through a speed reducing gear of ratio 9:1. The motor armature, with its shaft and gear wheel, has moment of inertia 0.6 kg-m2. The rotating part of the driven machine has moment of inertia 45 kg-m2. The driven machine has resisting torque of 100 N-m and the efficiency of reduction gear is 95%. Find the power which the motor must develop to drive the machine at a uniform speed of 160 r.p.m.

A

1764 W

B

2764 W

C

3764 W

D

4764 W

A gear train consist of spur gear as shown. Gear A receives 4kW of power at 750rpm through its shaft and rotates in CW direction. A gear train consist of spur gear as shown. Gear A receives 4kW of power at 750rpm through its shaft and rotates in CW direction. Calculate the torque on the gear C if number of teeth on gear A, B and C are 40, 70 and 30.

A

66N-m

B

68N-m

C

53N-m

D

45N-m

Consider two shafts connected with two gears as per the following options: 1. One on each shaft 2. Through an intermediate gear mounted on an intermediate shaft, and every shaft having one gear only 3. Through an intermediate gear mounted on an intermediate shaft, with the intermediate shaft having two gears, whereas the other shafts have one gear each Which of the above represent(s) a simple gear train?

A

1 only

B

1 and 2 only

C

2 and 3 only

D

1, 2 and 3

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

The moment of inertia of a uniform sphere of radius, r about an axis passing through its centre is given by $$\frac{2}{5}\left( {\frac{{4\pi }}{3}{r^5}\rho } \right).$$ A rigid sphere of uniform mass density $$\rho $$ and radius R has two smaller spheres of radii $$\frac{R}{2}$$ hollowed out of it as shown in the figure given below.
Classical Mechanics mcq question image

The moment of inertia of the resulting body about Y-axis is

A

$$\frac{{\pi \rho {R^5}}}{4}$$

B

$$\frac{{5\pi \rho {R^5}}}{{12}}$$

C

$$\frac{{7\pi \rho {R^5}}}{{12}}$$

D

$$\frac{{3\pi \rho {R^5}}}{4}$$

Let $${I_1}$$ and $${I_2}$$ represents mesh currents in the loop abcda and befcb respectively. The correct expression describing Kirchhoff's voltage loop law in one of the following loops is,
Electronics mcq question image

A

$$30{I_1} - 15{I_2} = 10$$

B

$$ - 15{I_1} + 20{I_2} = - 20$$

C

$$30{I_1} - 15{I_2} = - 10$$

D

$$ - 15{I_1} + 20{I_2} = 20$$

A planetary gear train is shown in the figure. Number of teeth on the sun gear A, planet gear B and fixed ring gear D are given by 30, 70 and 140 respectively. Module is taken as 5mm. A pair of spur gears consist of 25 teeth pinion meshing with a 115 teeth gear. The module is 5mm. Calculate the gear ratio.

A

5

B

4.6

C

5.2

D

4

The natural frequency of free torsional vibrations of a shaft is equal to (where q = Torsional stiffness of the shaft and $$I$$ = Mass moment of inertia of the disc attached at the end of a shaft)

A

$$2\pi \sqrt {\frac{{\text{q}}}{I}} $$

B

$$2\pi \sqrt {{\text{q}}I} $$

C

$$\frac{1}{{2\pi }}\sqrt {\frac{{\text{q}}}{I}} $$

D

$$\frac{1}{{2\pi }}$$

A multi-disc clutch has 3 discs on the driving shaft and 2 on the driven shaft. The outer radius is 100 mm and inside radius 40 mm. Considering uniform wear and µ = 0.25, find the maximum axial intensity of pressure between the discs for transmitting 30 kW at 1000 r.p.m.

A

0.4071 N/m2

B

40.71 N/mm2

C

407.1 N/m2

D

0.4071 N/mm2

Following is the data for transmission system of a Gear box reduction ratios.
1^st gear - 4.3 : 1
2^nd gear - 3.00 : 1
3^rd gear - 2.71 : 1
4^th gear - 1 : 1
Final drive reduction is 5.0 : 1
The overall reduction when the vehicle is driven in 2^nd gear is

A

3.00 : 1

B

13.55 : 1

C

5 : 1

D

15 : 1

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

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