Numerical Computation and Estimation - General Aptitude - General Aptitude (GA) Previous Year Questions

1

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

In abrasive jet machining, as the distance between the nozzle tip and the work surface increases, the material removal rate

A

increases continuously.

B

decreases continuously.

C

decreases, becomes stable and then increases.

D

increases, becomes stable and then decreases.

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2

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

In an interchangeable assembly, shafts of size \(25.000^{+0.040}_{+0.010}\) mm mate with holes of size \(25.000^{+0.050}_{+0.020}\) mm. The maximum interference (in microns) in the assembly is

A

40

B

30

C

20

D

10

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3

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

Oil flows through a 200 mm diameter horizontal cast iron pipe (friction factor, \(f = 0.0225\)) of length 500 m. The volumetric flow rate is 0.2 \(m^3/s\). The head loss (in m) due to friction is (assume \(g = 9.81\ m/s^2\))

A

116.18

B

0.116

C

18.22

D

232.36

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4

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

Steam enters an adiabatic turbine operating at steady state with an enthalpy of 3251.0 kJ/kg and leaves as a saturated mixture at 15 kPa with quality (dryness fraction) 0.9. The enthalpies of the saturated liquid and vapor at 15 kPa are \(h_f = 225.94\ kJ/kg\) and \(h_g = 2598.3\ kJ/kg\) respectively. The mass flow rate of steam is 10 kg/s. Kinetic and potential energy changes are negligible. The power output of the turbine in MW is

A

6.5

B

8.9

C

9.1

D

27.0

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5

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

The following are the data for two crossed helical gears used for speed reduction:
Gear I : Pitch circle diameter in the plane of rotation 80 mm and helix angle 30°
Gear II : Pitch circle diameter in the plane of rotation 120 mm and helix angle 22.5°
If the input speed is 1440 rpm, the output speed in rpm is

A

1200

B

900

C

875

D

720

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6

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

A solid cylinder of diameter 100 mm and height 50 mm is forged between two frictionless flat dies to a height of 25 mm. The percentage change in diameter is

A

0

B

2.07

C

20.7

D

41.4

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7

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

The velocity triangles at the inlet and exit of the rotor of a turbomachine are shown. \(V\) denotes the absolute velocity of the fluid, \(W\) denotes the relative velocity of the fluid and \(U\) denotes the blade velocity. Subscripts 1 and 2 refer to inlet and outlet respectively. If \(V_2 = W_1\) and \(V_1 = W_2\), then the degree of reaction is

A

0

B

1

C

0.5

D

0.25

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8

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

Which one of the following configurations has the highest fin effectiveness?

A

Thin, closely spaced fins

B

Thin, widely spaced fins

C

Thick, widely spaced fins

D

Thick, closely spaced fins

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9

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

In the mechanism given below, if the angular velocity of the eccentric circular disc is 1 rad/s, the angular velocity (rad/s) of the follower link for the instant shown in the figure is
Note: All dimensions are in mm.

A

0.05

B

0.1

C

5.0

D

10.0

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10

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

A circular solid disc of uniform thickness 20 mm, radius 200 mm and mass 20 kg, is used as a flywheel. If it rotates at 600 rpm, the kinetic energy of the flywheel, in Joules is

A

395

B

790

C

1580

D

3160

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11

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

Details pertaining to an orthogonal metal cutting process are given below.
Chip thickness ratio 0.4
Undeformed thickness 0.6 mm
Rake angle +10°
Cutting speed 2.5 m/s
Mean thickness of primary shear zone 25 microns
The shear strain rate in s^{-1} during the process is

A

0.1781×10^5

B

0.7754×10^5

C

1.0104×10^5

D

4.397×10^5

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12

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

An incompressible fluid flows over a flat plate with zero pressure gradient. The boundary layer thickness is 1 mm at a location where the Reynolds number is 1000. If the velocity of the fluid alone is increased by a factor of 4, then the boundary layer thickness at the same location, in mm will be

A

4

B

2

C

0.5

D

0.25

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13

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

Calculate the punch size in mm, for a circular blanking operation for which details are given below.
Size of the blank 25 mm
Thickness of the sheet 2 mm
Radial clearance between punch and die 0.06 mm
Die allowance 0.05 mm

A

24.83

B

24.89

C

25.01

D

25.17

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14

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

In a single pass rolling process using 410 mm diameter steel rollers, a strip of width 140 mm and thickness 8 mm undergoes 10 % reduction of thickness. The angle of bite in radians is

A

0.006

B

0.031

C

0.062

D

0.600

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15

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

In a DC arc welding operation, the voltage-arc length characteristic was obtained as V_arc = 20 + 5l where the arc length l was varied between 5 mm and 7 mm. Here V_arc denotes the arc voltage in Volts. The arc current was varied from 400 A to 500 A. Assuming linear power source characteristic, the open circuit voltage and the short circuit current for the welding operation are

A

45 V, 450 A

B

75 V, 750 A

C

95 V, 950 A

D

150 V, 1500 A

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16

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

A large tank with a nozzle attached contains three immiscible, inviscid fluids as shown. Assuming that the changes in h_1, h_2 and h_3 are negligible, the instantaneous discharge velocity is

A

\(\sqrt{2gh_3 \left(1 + \frac{\rho_1}{\rho_3}\frac{h_1}{h_3} + \frac{\rho_2}{\rho_3}\frac{h_2}{h_3}\right)}\)

B

\(\sqrt{2g(h_1 + h_2 + h_3)}\)

C

\(\sqrt{2g \left(\frac{\rho_1 h_1 + \rho_2 h_2 + \rho_3 h_3}{\rho_1 + \rho_2 + \rho_3}\right)}\)

D

\(\sqrt{2g \left(\frac{\rho_1 h_1 + \rho_2 h_2 + \rho_3 h_3}{\rho_1 h_2 + \rho_2 h_3 + \rho_3 h_1}\right)}\)

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17

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

Water ($C_p = 4.18 kJ/kg.K$) at $80^{\circ}C$ enters a counterflow heat exchanger with a mass flow rate of $0.5 kg/s$. Air ($C_p = 1 kJ/kg.K$) enters at $30^{\circ}C$ with a mass flow rate of $2.09 kg/s$. If the effectiveness of the heat exchanger is 0.8, the LMTD (in $^{\circ}C$) is

A

40

B

20

C

10

D

5

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18

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

A solid circular shaft needs to be designed to transmit a torque of $50 N.m$. If the allowable shear stress of the material is $140 MPa$, assuming a factor of safety of 2, the minimum allowable design diameter in mm is

A

8

B

16

C

24

D

32

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19

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

A force of $400 N$ is applied to the brake drum of $0.5 m$ diameter in a band-brake system as shown in the figure, where the wrapping angle is $180^{\circ}$. If the coefficient of friction between the drum and the band is 0.25, the braking torque applied, in $N.m$ is

A

100.6

B

54.4

C

22.1

D

15.7

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20

2012 · General Aptitude (GA) · General Aptitude · Numerical Computation and Estimation

Mechanical Engineering (ME) 2012

The maximum force F in kN that can be applied at C such that the axial stress in any of the truss members DOES NOT exceed 100 MPa is

A

8.17

B

11.15

C

14.14

D

22.30

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