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

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.

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

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

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

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,

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

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

The pictorial view of the frustum of a square pyramid is shown in figure 'X'. Its top view, when viewed in the direction of the arrow, will look like which of the given alternatives 1, 2, 3 and 4?

A

1

B

2

C

3

D

4

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