ISRO Scientist or Engineer Mechanical 2018

ISRO Scientist or Engineer Mechanical 2018 - Question 1

Report

An expansion process as per law PV = constant is known as

A

parabolic expansion

B

hyperbolic expansion

C

isentropic expansion

D

free expansion

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 2

Report

Speed of an aeroplane is measured by

A

pitot tube

B

hot wire anemometer

C

venturimeter

D

rotameter

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 3

Report

Euler's dimensionless number relates the following

A

inertial force and gravity

B

viscous force and inertial force

C

pressure force and inertial force

D

viscous force and pressure force

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 4

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A simple compressible substance inside a cylinder undergoes a change of state quasistatically, isothermally and at constant pressure of 1.5 MPa. If the enthalpy change for the system is 4000 kJ at $$150^\circ C$$, what is the corresponding change in its entropy?

A

9.45 kJ/K

B

26.67 kJ/K

C

14.17 kJ/K

D

0

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 5

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The velocity of sound in a gaseous medium at a temperature of 400 K is 400 m/s. If the temperature of the medium is increased to 600 K, the velocity of sound will be nearly,

A

400 m/s

B

490 m/s

C

600 m/s

D

None of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 6

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Stress strain relation of the Newtonian fluid is

A

parabolic

B

linear

C

hyperbolic

D

inverse type

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 7

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Speed of sound in water is equal to (K-bulk modulus, $$\rho$$-density)

A

$$\sqrt{\frac{K}{\rho}}$$

B

$$\sqrt{K \rho}$$

C

$$\sqrt{\frac{\rho}{K}}$$

D

$$\frac{K}{\rho}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 8

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If the stream function of a two dimensional flow is $$\psi = 5 xy$$. then the velocity at a point (3, 4)is

A

25 m/s

B

20 m/s

C

7 m/s

D

5 m/s

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 9

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A glass tube of 8 mm diameter is immersed in water. Surface tension of water is 0.0075 kg/m and rise of water in the tube due to capillary effect is

A

7.5 mm

B

3.75 mm

C

11.25 mm

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 10

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An impulse turbine produces 125 hp under a head of 25 meter. By what percentage should the speed be increased for a head of 100 meter.

A

25%

B

50%

C

75%

D

100%

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 11

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The specific speed of a centrifugal pump, delivering 1000litres of water per second against a head of 16 meter at 800 rom

A

50 rpm

B

100 rpm

C

150 rpm

D

200 rpm

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 12

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A pipe of 0.1 m$$^2$$ suddenly changes to 0.5 m$$^2$$ area. The quantity of water flowing in the pipe is 0.5 m$$^3$$/s. Head loss due to sudden enlargement is nearly

A

0.025 m

B

0.05 m

C

0.8 m

D

1.2 m

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 13

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Efficiency of a centrifugal pump is maximum when the blades are

A

straight

B

forward curved

C

backward curved

D

forward and backward curved

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ISRO Scientist or Engineer Mechanical 2018 - Question 14

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The critical radius of insulation for a spherical shell is

A

$$\frac{thermal conductivity of insulating material}{heat transfer coefficient at the outer surface}$$

B

$$\frac{2 \times thermal conductivity of insulating material}{heat transfer coefficient at the outer surface}$$

C

$$\frac{thermal conductivity of insulating material}{2 \times heat transfer coefficient at the outer surface}$$

D

$$\frac{heat transfer coefficient at the outer surface}{thermal conductivity of insulating material}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 15

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If the temperature of a solid surface changes from $$27^circ C$$ to $$81^circ C$$, then its emissive power changes in the ratio of nearly

A

81

B

9

C

1.49

D

1.94

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 16

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The heat removal rate from a refrigerated space is 7.2 kW and the power input to the compressor is 1.8 kW. The coefficient of performance (COP) of the refrigerator is

A

4

B

5

C

1.25

D

0.25

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 17

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For a fluid having Prandtl number equal to unity, the relation between hydrodynamic boundary layer thickness ($$\delta_1$$) and thermal boundary layer thickness ($$\delta_2$$)

A

$$\delta_1 > \delta_2$$

B

$$\delta_1 < \delta_2$$

C

$$\delta_1 = \delta_2$$

D

$$\delta_2 = \frac{\delta_1}{3}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 18

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Life of a ball bearing at a load of 10 kN is 24000 hours. If the load is increased to 20 kN (all other conditions are same), its life in hour is

A

1000 h

B

3000 h

C

6000 h

D

12000 h

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 19

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The impact strength of a material is an index of its

A

fatigue strength

B

tensile strength

C

hardness

D

toughness

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 20

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Which of the following order of crystal structure will match with metals lron-Nickel Titanium in that order at room temperature?

A

BCC - HCP - FCC

B

FCC - BCC - HCP

C

HCP - FCC - BCC

D

BCC - FCC - HCP

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 21

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In a machining operation cutting speed is reduced by 50%. Assuming n = 0.5, C = 300 in Taylor's equation. The increase in tool life is

A

2

B

4

C

8

D

16

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 22

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In a linear arc welding process, the heat input per unit length is inversely proportional to

A

welding current

B

welding speed

C

welding voltage

D

duty cycle of power source

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ISRO Scientist or Engineer Mechanical 2018 - Question 23

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The welding process which uses a blanket of fusible granular flux is

A

submerged arc welding

B

tungsten inert gas welding

C

electroslag welding

D

theromit welding

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ISRO Scientist or Engineer Mechanical 2018 - Question 24

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Two non-zero vectors are parallel if their vector productis

A

1

B

0

C

-1

D

$$\infty$$

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ISRO Scientist or Engineer Mechanical 2018 - Question 25

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If eigen value of a matrix A is $$\lambda$$, then the eigen value of A2 is

A

$$1$$

B

$$\frac{1}{\lambda}$$

C

$$\frac{1}{\lambda^2}$$

D

$$\lambda^2$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 26

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The value of $$\lim_{x \rightarrow \infty}\frac{\sin x}{x}$$ is equal to

A

1

B

-1

C

infinity

D

zero

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ISRO Scientist or Engineer Mechanical 2018 - Question 27

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If $$f(x) = \frac{1 - x}{1 + x}$$ then $$f \left(\frac{1}{x}\right)$$ is equal to

A

f(x)

B

-f(x)

C

f(-x)

D

$$\pm$$ f(x)

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 28

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Inverse Laplace transform of $$\frac{S}{S^2 + a^2}$$ is

A

$$\frac{e^{at} + e^{-at}}{2}$$

B

$$\frac{e^{at} - e^{-at}}{2}$$

C

$$\frac{e^{at}}{2}$$

D

$$\frac{e^{-at}}{2}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 29

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One dimensional wave equation is

A

$$\frac{\partial^2 y}{\partial t^2} = \propto^2 \frac{\partial^2 y}{\partial x^2}$$

B

$$\frac{\partial y}{\partial t} = \propto^2 \frac{\partial^2 y}{\partial x^2}$$

C

$$\frac{\partial^2 y}{\partial t^2} + \frac{\partial^2 y}{\partial x^2} = 0$$

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 30

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A composite bar made of Aluminium and Steel is fixed rigidly at supports P and Q as shown in figure. When the temperature of the bar is increased by $$10^\circ C$$, the reactions at the supports are (given $$E_{al} = 70 GPa, E_s = 210 GPa, \alpha_{al} = 11E - 6$$ mm/mm$$^\circ C$$ and $$\alpha_s = 12E - 6 mm/mm^\circ C$$)

A

4060 N

B

6780 N

C

12240 N

D

2412 N

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 31

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Torque, Tis applied at the free end of a stepped rod of circular cross-section as shown in figure. If the shear modulus of the material is G, the angular twist, $$\theta$$ at free end will be

A

$$\frac{12 TL}{G \pi d^4}$$

B

$$\frac{24 TL}{G \pi d^4}$$

C

$$\frac{36 TL}{G \pi d^4}$$

D

$$\frac{48 TL}{G \pi d^4}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 32

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In mostbrittle materials, the ultimate strength in compression is larger than the ultimate strength in tension due to

A

Necking in tension

B

Presence of flaws and microscopic cracksor cavities

C

Non-linearity of stress-strain diagram

D

Severity of tensile stress as compared to compressive stress

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 33

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If the natural frequency of a spring mass system on earth is f, its natural frequency on moon where acceleration due to gravity is one-sixth of that on earth will be

A

$$\frac{f}{6}$$

B

$$6f$$

C

$$\frac{f}{\sqrt{6}}$$

D

$$f$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 34

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A solid shaft can resist a bending moment of 6 KN-m and a torque of 8 kN-m applied together. The maximum torque that the shaft can resist when applied alone is

A

7 kN-m

B

48 kN-m

C

10 kN-m

D

14 kN-m

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 35

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Two shafts of the same length and material are connectedin series, if the ratio of their diameters is 2, then the ratio of their angles of twist will be

A

4

B

8

C

16

D

32

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 36

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A concentrated load of F acts on a simply supported beam of span L at a distance of $$\frac{L}{3}$$ from left support, the bending momentat this location C is

A

$$\frac{2FL}{3}$$

B

$$\frac{4FL}{9}$$

C

$$\frac{2FL}{9}$$

D

$$\frac{4FL}{3}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 37

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Euler's critical buckling load for a column fixed at both ends is

A

$$\frac{2 \pi^2 EI }{L^2}$$

B

$$\frac{\pi^2 EI }{2L^2}$$

C

$$\frac{4 \pi^2 EI }{L^2}$$

D

$$\frac{\pi^2 EI }{4L^2}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 38

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A truck hauls a trailer at 60 km/hour when exerting a steady pull of 600 N. If the work is done for 40 minutes, the power required is

A

6 kW

B

4 kW

C

2.4 kW

D

10 kW

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 39

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A perfectly balanced rotor shaft supported between short bearings at both ends shows a deflection of 2mm at middle. Then the critical speed of the shaft in rom will be nearly,

A

335

B

670

C

2010

D

1340

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 40

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If an element is loaded as shownin figure below, the von-Mises stress will be close to

A

180 MPa

B

350 MPa

C

255 MPa

D

495 MPa

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 41

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The pressure P of a gasin terms of its mean kinetic energy per unit volume E is equal to

A

$$\frac{E}{3}$$

B

$$\frac{E}{2}$$

C

$$\frac{3E}{4}$$

D

$$\frac{2E}{3}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 42

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Work done in a free expansion process is

A

+ve

B

-ve

C

zero

D

none of the above

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 43

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If the value of rn is infinitely large in a polytropic process $$PV^n = C$$, then the process is Known as constant

A

volume

B

pressure

C

temperature

D

entropy

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 44

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During the charging of a storage battery, the current | is 20 A and the voltage E is 12.8 V. The rate of heat transfer from the battery is 16 W. At whatrate is the internal
energy increasing?

A

256 J/s

B

272 J/s

C

0

D

240 J/s

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 45

Report

The compression ratio for diesel engines is close to

A

3 to 6

B

5 to 8

C

15 to 20

D

20 to 30

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 46

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One kg of carbon monoxide requires, how much quantity of oxygen to produce 11/7 kg of carbondioxide gas

A

$$\frac{4}{7}$$ kg

B

$$\frac{11}{4}$$ kg

C

$$\frac{9}{7}$$ kg

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 47

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The entropy of water at O K is assumed to be

A

1 J/K

B

-1 J/K

C

10 J/K

D

0

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 48

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For an irrotational flow, $$\frac{\partial^2 \phi}{\partial x^2} + \frac{\partial^2 \phi}{\partial y^2} = 0$$ is the equation given by

A

Cauchy-Riemann

B

Reynolds

C

Laplace

D

Bernoulli

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 49

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In a centrifugal pump casing, the flow of water leaving the impeller is

A

rectilinear flow

B

free vortex motion

C

radial flow

D

forced vortex

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 50

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For a two stage reciprocating compressor, compression from P1 to P3 is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the
same polytropic process and the atmospheric pressure is Pa, then the intermediate pressure P2 is given by

A

$$P2 = \frac{(P1 + P3)}{2}$$

B

$$P2 = \sqrt{P1.P3}$$

C

$$P2 = Pa\sqrt{\frac{P3}{P1}}$$

D

$$P2 = Pa\sqrt{\frac{P1}{P3}}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 51

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The degree of reaction in an axial flow compressor is defined as the ratio of static enthalpy rise in the

A

rotor to static enthalpy rise in the stator

B

stator to static enthalpy rise in the rotor

C

rotor to static enthalpyrise in the stage

D

stator to static enthalpy rise in the stage

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 52

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The frequency of ultrasonic waves is

A

less than 20 Hz

B

between 20 to 10000 Hz

C

between 20 to 20000 Hz

D

above 20000 Hz

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 53

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Loudness of the sound does not change with the change in

A

frequency

B

amplitude

C

distance from the source of sound

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 54

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The hydraulic diameter, $$D_h$$, of a rectangular channel with sides ‘a’ and ‘b’ is

A

$$D_h = \frac{4ab}{2a + b}$$

B

$$D_h = \frac{2ab}{a + b}$$

C

$$D_h = \frac{2ab}{2a + b}$$

D

$$D_h = \frac{4ab}{a + b}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 55

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Which of the following has maximum value of thermal conductivity?

A

steel

B

copper

C

brass

D

aluminium

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 56

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The value of Biot number is very small (< 0.01) when

A

conductive resistance of the fluid is negligible.

B

conductive resistance with in the body is negligible.

C

convective resistance of a fluid surface of the body is negligible.

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 57

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A steam pipe is to be insulated by 2 insulating materials put over each other. For best results

A

better insulation should be put over pipe and inferior one over it.

B

inferior insulation should be put over pipe and better one over it.

C

both may put in any order.

D

unpredictable.

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 58

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The main objective of ‘shot peening’ is to improve which property of metal parts

A

fatigue strength

B

ductility

C

surface finish

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 59

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A hole is of dimension $$\phi 60^{\frac{+0.015}{-0.000}}$$ and the corresponding shaft is of dimension $$\phi 60^{\frac{+0.011}{-0.001}}$$. When they are assembled they will form a

A

interference fit

B

clearance fit

C

transition fit

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 60

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Which of the following carbon steels is most weldable?

A

1.0% carbon steel

B

0.38% carbon steel

C

0.5% carbon steel

D

0.15% carbon steel

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 61

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A small percentage of Boron is added to steel in order to

A

increase endurance strength

B

reduce machinability

C

increase wear resistance

D

increase hardenability

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 62

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A material that exhibits the same elastic properties in all directions at a point is called

A

homogeneous

B

heterogenous

C

isotropic

D

orthotropic

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 63

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No of atoms per unit cell of a face centered cubic (FCC) lattice is

A

14

B

7

C

4

D

10

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 64

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In asheet metal of 3 mm thickness of a hole of 7 mm diameter needs to be punched. The yield strength in tension of the sheet material is 120 MPa and its ultimate shear strength is 100 MPa. The force required to punch the hole is

A

7.92 kN

B

11.6 kN

C

6.6 kN

D

13.9 kN

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 65

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Profile of a gear tooth can be checked by

A

sine bar

B

bench micrometer

C

optical pyrometer

D

optical projector

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 66

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The reflector combined with auto collimator can be used for checking

A

parallelism

B

circularity

C

surface finish

D

alignment

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 67

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PERT has following time estimate

A

one time estimate

B

two time estimate

C

three time estimate

D

nil time estimate

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 68

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Which of the following is an amorphous material?

A

mica

B

lead

C

rubber

D

glass

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 69

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In a party, each person shook hands with every other person present. The total number of hand shakes was 45. The number of people in the part are

A

12

B

10

C

8

D

6

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 70

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Which of the following method is said to be a direct method in numerical methods?

A

Regula-Falsi method

B

Gauss Siedel method

C

Newton-Raphson method

D

Gauss elimination method

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ISRO Scientist or Engineer Mechanical 2018 - Question 71

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‘If X is a normal variable with mean $$\mu$$ and standard deviation $$\sigma$$, then the mean and standard deviation of the variable $$Z = \frac{X - \mu}{\sigma}$$ is

A

1 and 0 respectively

B

$$\mu$$ and $$\sigma$$ respectively

C

O and 1 respectively

D

none of these

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 72

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Example for an elliptic partial differential equation is

A

$$U_{xx} + U_{yy} = 0$$

B

$$U_t = c^2 U_{xx}$$

C

$$U_{tt} = c^2 U_{yy}$$

D

$$yU_{xx} + U_{yy} = 0$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 73

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The solution of the equation $$y'' + y = 0$$ satisfy the condition $$y(0) = 1, y\left(\frac{\pi}{2}\right) = 2$$, is

A

$$\cos x + 2 \sin x$$

B

$$\cos x + \sin x$$

C

$$2 \cos x + \sin x$$

D

$$2(\cos x + 2 \sin x)$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 74

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For the spring system given in figure, the equivalent stiffness is

A

$$\frac{5K}{2}$$

B

$$\frac{2K}{5}$$

C

K

D

3K

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 75

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A round uniformly tapered bar of length L and Young’s modulus E has diameter of ‘a’ at one end and ‘2d’ at the other end. If the bar is pulled by an axial force F, the extension produced will be

A

$$\frac{2FL}{(\pi E d^2)}$$

B

$$\frac{4FL}{(\pi E d^2)}$$

C

$$\frac{8FL}{(\pi E d^2)}$$

D

$$\frac{16FL}{(\pi E d^2)}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 76

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Two blocks A and B of 1 kg each are kept on flat surface, one above other. The coefficient of friction between each contacting pair is 0.2. If the lower block is pulled with a horizontal force F, the minimum value of F for which the slip occurs between the blocks is nearly

A

5.9 N

B

4.9 N

C

18.4 N

D

0

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 77

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A solid metal bar of uniform diameter D and length L is hung vertically. If $$\rho$$ is density and E is the Young’s modulus, then the total elongation due to self weight is

A

$$\frac{\rho L g}{2E}$$

B

$$\frac{\rho L^2 g}{2E}$$

C

$$\frac{\rho E g}{2L^2}$$

D

$$\frac{\rho L^2 g}{E}$$

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 78

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A circular solid disc of uniform thickness 20 mm, radius 400 mm and mass 10 kg, is used as a flywheel. If it rotates at 300 rom, the kinetic energy of the flywheel, in Joules is

A

395

B

790

C

1580

D

3160

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 79

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If the length of the cantilever beam is reduced to $$\frac{1}{4}th$$, the natural frequency of the mass M at the end of this cantilever beam of negligible mass will be increased by a factor of

A

2

B

$$\sqrt{8}$$

C

4

D

8

View Solution

ISRO Scientist or Engineer Mechanical 2018 - Question 80

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The relationship between the linear elastic properties Young’s modulus (E), rigidity modulus (G) and Bulk modulus (K) is given by

A

$$\frac{9}{E} = \frac{3}{K} + \frac{1}{G}$$

B

$$\frac{1}{E} = \frac{9}{K} + \frac{3}{G}$$

C

$$\frac{3}{E} = \frac{9}{K} + \frac{1}{G}$$

D

$$\frac{9}{E} = \frac{1}{K} + \frac{3}{G}$$

View Solution