ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 1

Report

The condition of stable equilibrium fora floating body is:

A

metacentre coincides with centre of gravity

B

metacentre is below centre of gravity

C

metacentre is above centre of gravity

D

centre of buoyancyis above centre of gravity

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 2

Report

The thickness of turbulent boundary layer at a distance x from the leading edge overa flat plate vvaries as

A

$$x^{0.8}$$

B

$$x^{0.5}$$

C

$$x^{0.2}$$

D

$$x^{0.6}$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 3

Report

The diameters of a pipe at the sections 1 and 2 are 10 cm and 15 cm respectively. Velocity of water flowing through the pipe at section 1 is 5 m/s. velocity at section 2 in m/s and discharge in cmm is

A

2.2 & 2.4

B

2.7 & 2.8

C

2.1 & 2.4

D

2.4 & 2.6

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 4

Report

The velocity distribution for flow over flat plate is given $$u = \frac{3}{4}y - y^2$$ in which u is the velocity in m/s at a distance y meter above the plate. Shear stress at $$y = 0.15 m$$ is (Take $$\mu$$ for fluid = 8.5 poise)

A

0.3825 Pa

B

0.3815 Pa

C

0.3835 Pa

D

0.3845 Pa

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 5

Report

A gas weighs 16 N/m$$^3$$ at 288 K and at an adiabatic pressure of 25 N/cm$$^2$$. Its gas constant is

A

532 J/kg K

B

544 J/kg K

C

553 J/kg K

D

523 J/kg K

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 6

Report

A pipe line AB of diameter 30 cm and of length 400 m carries water at the rate of 50 liters/sec. The flow takes place from A to B where point B is 30 meters above A. Pressure
at B is 2 ksc. Pressure at Ais (Take f = 0:008)

A

5.2 ksc

B

5.3 ksc

C

5.0 ksc

D

5.1 ksc

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 7

Report

A nozzle is fitted at the end of a pipe of length 300m and of diameter 10 cm for transmitting water. What is the diameter of the nozzle considering maximum transmission
of powerthrough the nozzle (f = 0.009)

A

2.6 cm

B

2.5 cm

C

2.4 cm

D

2.7 cm

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 8

Report

A turbine develops 500 kW under a head of 100 meters at 200 RPM.Its normal speed and powerunder a head of 81 meters

A

184 RPM and 375 kW

B

180 RPM and 365 kW

C

184 RPM and 370 kW

D

180 RPM and 361 kW

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 9

Report

Number of degrees of freedom in a Ball and socket joint:

A

1

B

2

C

3

D

0

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 10

Report

Two inelastic spheres of masses 10 kg each move with velocities of 15m/s and 5m/s respectively in the same direction. The loss in kinetic energy when theycollide

A

500 Nm

B

0

C

250 Nm

D

1000 Nm

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 11

Report

In order to have maximum powerfrom a Pelton turbine, the bucket speed must be

A

equalto the jet speed

B

equalto half of the jet speed

C

equal to twice the jet speed

D

independentof the jet speed

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 12

Report

The alloying element mainly used to improve the endurancestrength ofsteel materials is

A

Nickel

B

Vanadium

C

Molybdenum

D

Tungsten

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 13

Report

The percentage improvement in powercapacity of a flat belt drive, when the wrap angle at the driving pulley is increased from $$150^\circ$$ to $$210^\circ$$ by an idler arrangement fora friction coefficient of 0.3 is

A

25.21

B

33.92

C

40.17

D

67.85

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 14

Report

In an interchangeable assembly, shaft of size $$25.000_{-0.01}^{+0.04}$$ mm. mates with a hole of size $$25.000_{-0.02}^{+0.03}$$ mm. Maximum interference in micronsin the assembly is

A

40

B

30

C

10

D

20

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 15

Report

A column has a rectangular cross section of 10 $$\times$$ 20 mm and a length of 1m. The slenderness ratio of the columnis close to

A

200

B

346

C

477

D

1000

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 16

Report

A thin cylinder of inner radius 500 mm and thickness 10mm is subjected to an internal pressure of 5 MPa. The average hoop stress in MPa is

A

100

B

250

C

500

D

1000

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 17

Report

A circular disk of uniform thickness 20 mm, radius 200 mm and mass 20 kg is used as flywheel. If it rotates at 600 rpm, kinetic energy of flywheel in Joule is

A

395

B

790

C

1580

D

3160

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 18

Report

A vibration system consists of a mass of 175 kg, a spring stiffness 700 N/cm and damper with a damping coefficient of 7 N cm$$^{-1}$$ sec. Damping factor of the system is

A

0.15

B

0.25

C

0.2

D

0.1

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 19

Report

Two cutting tools are being compared for a machining operation. The tool life equations are Carbide tool : $$VT^{1.6} = 3000$$; HSS tool : $$VT^{0.6} = 200$$, where V is the cutting speed in m/min and T is tool life in min. The carbide tool will provide higher tool life, if the cutting speed in m/min exceeds

A

39.4

B

15

C

60

D

49.3

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 20

Report

The diameter of suction side of a reciprocating compressor compared to its delivery side is

A

smaller

B

equal

C

bigger

D

varies according to capacity

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 21

Report

Two crossed helical gears are used for speed reduction. Gear A haspitch circle diameter in the plane of rotation 80mm and helix angle 30 deg; Gear B . Gear A haspitch circle
diameter in the plane of rotation 120mm andhelix angle 22.5 deg; If the input speed is 1440 RPM, then output speed in RPM is

A

1200

B

875

C

900

D

700

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 22

Report

The moisture in a refrigerant is removedby :

A

dehumidifiers

B

safety relief valve

C

driers

D

expansion valve

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 23

Report

In an arc welding process, the voltage and current are 25 V and 300 A respectively. The are heat transfer efficiency is 0.85 and welding speed is 8mm/sec. the net heat input (in J/mm) is:

A

64

B

797

C

1103

D

79700

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 24

Report

Hardness of steel greatly improves with

A

annealing

B

cyaniding

C

normalizing

D

tempering

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 25

Report

A

P-2, Q-5, R-1, S-3

B

P-6, Q-3, R-4, S-4

C

P-4, Q-1, R-6, S-2

D

P-5, Q-4, R-2, S-6

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 26

Report

For a perfect gas

A

P-4, Q-2, R-3, S-6

B

P-3, Q-5, R-4, S-1

C

P-2, Q-4, R-1, S-5

D

P-4, Q-5, R-6, S-1

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 27

Report

If a mass of moist air in an airtight vessel is heated to a higher temperature, then

A

Specific humidity of air increases

B

Specific humidity of air decreases

C

Relative humidity of air increases

D

Relative humidity of air decreases

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 28

Report

Threaded bolts of A and B of same material and length are subjected to identical tensile load. If the elastic strain energy stored in bolt A is 4 times that of bolt B and the mean diameter of bolt A is 12mm, then mean diameterof bolt B is

A

16

B

24

C

36

D

48

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 29

Report

In a condenser of a power plant, the steam condenses at a temperature of 333 K. The cooling water enters at 303 K and leaves at 318 K. The logarithmic mean temperature
difference (LMTD)of the condenser is

A

$$16.2^\circ C$$

B

$$21.6^\circ C$$

C

$$30^\circ C$$

D

$$37.5^\circ C$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 30

Report

The shear strength of a sheet metal is 300 Mpa. The blanking force required to produce a blank of 100 mm diameter from a 1.5mm thick sheet is

A

45 kN

B

70 kN

C

141 kN

D

350 kN

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 31

Report

A heat engine is supplied heat at the rate of 1700 kJ/min and gives an output of 9 kW. Thermalefficiency and heat rejection in kW of heat engine is

A

34.0%, 11.0

B

28.3%, 10.0

C

31.76%, 19.33

D

32.3, 9.83

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 32

Report

When we have combinedfree and forced convection, Gr/Re$$^2$$ is

A

greater than 1

B

less than 1

C

almost equal to 1

D

equal to Peclet Number.

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 33

Report

A refrigerator and heat pump operate between the same temperature limits. COP of refrigerator is 4, COP of heat pump would be

A

3

B

5

C

4

D

data not adequate

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 34

Report

A carnot refrigerator requires 1.25 kW perton ofrefrigeration to maintain a temperature of 233 K.Its higher operating temperature of the cycle

A

318 K

B

313 K

C

315 K

D

316 K

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 35

Report

The work input to air compressor is minimum if the compression law followed is

A

isentropic

B

PV = C

C

$$PV^{1.2} = C$$

D

$$PV^{1.35} = C$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 36

Report

Operating pressures of the refrigerants at the evaporator in the ascending order for any application are

A

R11, R12, R717, R22

B

R22, R717, R12, R11

C

R11, R12, R22, R717

D

R717, R22, R11, R12

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 37

Report

For vapour compression system using R717 the material of pipe is

A

steel

B

copper

C

Brass

D

Aluminium

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 38

Report

Air at DBT of 308 K and DPTof 293 K passes through a cooling coil which is maintained at 298 K. The process would be

A

cooling and de humidification

B

sensible cooling

C

cooling and humidification

D

cannot predict

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 39

Report

Room sensible heat loss is 30000kJ/min and room latent heat loss is 20000 kJ/min. Sensible heat factor is

A

-0.6

B

0.6

C

0.3

D

3

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 40

Report

Domestic refrigerator working on vapour compression cycle uses the following type of expansion device

A

Manually operated valve

B

thermostatic valve

C

expansion valve

D

capillary tube

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 41

Report

An incompressible fluid flows overa flat plate and its boundary layer thickness at certain location is 1mm for Reynolds Numberof 1000. If the velocity is increased by a factorof 4, then the boundarylayer thickness at that location in mm will be

A

4

B

0.25

C

0.5

D

2

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 42

Report

A room contains 35 kg of dry air and 0.5 kg of water vapour. Total pressure and temperature in the room is 100kPa and 298 K.Saturation pressure of water at 298 is 3.17 kPa. Relative humidity of air in that room is

A

67%

B

55%

C

83%

D

71%

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 43

Report

An ideal brayton cycle operating between the pressure limits of 1 bar and 6 bar, has minimum and maximum temperature of 300 and 1500 K. Ratio of specific heat of working
fluid is 1.4. Approximate final temperatures in Kelvin at the end of compression and expansion respectively are

A

500 and 900

B

900 and 500

C

500 and 500

D

900 and 900

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 44

Report

Condition of perfect Vacuumis attained at temperature of

A

$$-273^\circ C$$

B

$$0^\circ C$$

C

273 K

D

can't be attained

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 45

Report

Two identical ball bearings P and Q are operating at loads 15 KN and 45 KN respectively. The ratio of life of bearing P to Q is

A

81

B

27

C

9

D

3

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 46

Report

If a certain amount of dry ice is mixed with same amount of waterat 80°C, then the final temperature of the mixture is

A

$$0^\circ C$$

B

$$80^\circ C$$

C

$$40^\circ C$$

D

$$60^\circ C$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 47

Report

The leaks in a refrigeration system using Freon is detected using

A

smell

B

halide torch

C

sulphur sticks

D

using reagents

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 48

Report

Presence of moisture in the refrigerant affects the working of

A

condenser

B

evaporator

C

expansion valve

D

compressor

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 49

Report

In SI unit, one ton of refrigeration is

A

210 kJ/min

B

21 kJ/min

C

420 kJ/min

D

840 kJ/min

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 50

Report

On the pressure — enthalpy diagram, condensation and de-superheating is represented by a horizontal line because the process

A

involves no change in volume

B

takes place constant temperature

C

takes place at constant pressure

D

takes place at constant entropy

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 51

Report

Generation of heating at one junction and cooling at other by passing direct current through a pair of dissimilar materials is

A

Seebeck effect

B

Joule effect

C

Peltier effect

D

Thomson effect

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 52

Report

Power consumption of centrifugal fans varies with speed (N) and diameter (D) as

A

$$N^3D^4$$

B

$$N^5D^3$$

C

$$N^2D^5$$

D

$$N^3D^5$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 53

Report

Sol-air temperature for a wall of absorptivity 0.9, exposed to ambient temperature of $$35^\circ C$$, solar radiation of 260 W/sqm, outside heat transfer coefficient 23 W/sqm K is

A

$$45.2^\circ C$$

B

$$48^\circ C$$

C

$$41.2^\circ C$$

D

$$47.2^\circ C$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 54

Report

The recovery factor in flow of gases is a function of

A

Reynolds Number

B

Prandtl Number

C

Peclet Number

D

Rayleigh Number

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 55

Report

Adiabatic wall temperature is

A

equal to stagnation temperature

B

greater than stagnation temperature

C

less than stagnation temperature

D

the temperature of adiabatic surface

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 56

Report

A composite slab has two layers of different materials having thermal conductivities k and 2k. If each layer has the same thickness, the equivalent thermal conductivity of the slab is

A

3 k

B

$$N^5D^3$$

C

$$\frac{3}{2k}$$

D

$$\frac{4k}{3}$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 57

Report

Whena liquid flows through a tube with subcooled or saturated boiling the processis known as

A

Pool boiling

B

bulk boiling

C

Convection boiling

D

forced convection boiling

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 58

Report

For filmwise condensation, the heat transfer coefficient will be equal whether the tube is horizontal or vertical, when the ratio of length to diameter is

A

1.3

B

2.87

C

0.77

D

> 10

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 59

Report

Insulated tip temperature of a rectangular longitudinalfin will be equal to

A

$$\theta_o \tan h$$ ml

B

$$\frac{\theta_o}{\sin h}$$ ml

C

$$\frac{\theta_o \tan h ml}{ml}$$

D

$$\frac{\theta_o}{\cos h}$$ ml

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 60

Report

The characteristic length computing Grashof number in the case of a horizontal cylinder is

A

diameter ofthe cylinder

B

length of the cylinder

C

radius of the cylinder

D

perimeter of the cylinder

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 61

Report

In liquid metal heat transfer for a fluid flowing through a tube, Nusselt number is a function of

A

Reynold Number

B

Prandtl Number

C

Peclet Number

D

Reynolds and Peclet Number

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 62

Report

Absorptivity of the grey body

A

varies with temperature

B

varies with wavelength of the incident ray

C

varies with wavelength and temperature of the incident ray

D

does not vary with wavelength and temperatureof the incident ray

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 63

Report

Gases have poor

A

transmissivity

B

absorptivity

C

reflectivity

D

emissivity

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 64

Report

Intensity of solar radiation in KW/sqm is about

A

1

B

3

C

5

D

2

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 65

Report

Match the following:

A

A-4, B-3, C-2, D-1

B

A-3, B-4, C-1, D-2

C

A-1, B-2, C-3, D-4

D

A-2, B-3, C-4, D-1

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 66

Report

In $$MLT \theta$$ system, the dimension of thermal conductivity is

A

$$ML^{-1}T^{-1} \theta^{-3}$$

B

$$MLT^{-1} \theta^{-1}$$

C

$$MLT^{-3} \theta^{-1}$$

D

$$MLT^{-2} \theta^{-1}$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 67

Report

For infinite parallel planes with emissivities 0.4 and 0.2, the interchange view factor for a radiation from surface 1 to surface 2 is about

A

0.4

B

0.6

C

0.2

D

0.15

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 68

Report

A chromel — alumel thermocouple of diameter 0.7mm is used to measure the temperature of a gas stream for which h= 600 W/sqm K. Acceptable reading of the temperature can be
taken after (specific heat = 400 J/kg K, Density = 8600 kg/cum)

A

1 second

B

4 seconds

C

2 seconds

D

3 seconds

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 69

Report

On a hot summerday, surface of the concrete highway may reach 328 K. Suppose a stream of wateris directed on the highwayso that the surface is suddenly lowered to 308 K. Time
taken in hours to cool the concrete to 318 K to a depth of 5 cm below the surface is:(Thermal diffusivity = 1.77 E-03 m$$^2$$/h)

A

1.2

B

1.4

C

1.8

D

1.6

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 70

Report

Hot surface at temperature 400 K having emissivity of 0.5 dissipates heat by radiation into a surrounding of 375 K.Its radiation heat transfer coefficient (W/sqm K) is

A

14.6

B

7.3

C

1.83

D

9.4

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 71

Report

Hot steel sphere of diameter 40mm is immersed in oil. If the heat transfer coefficient between the sphereand oil is 300 W/sqm K , then Biot Number is:(Take $$k_{steel}$$ = 50 W/m K and $$k_{oil}$$ = 0.2 W/m K)

A

0.04

B

0.12

C

10

D

0.24

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 72

Report

A metallic surface is maintained at 1000 K, the wavelength at which maximum spectral intensity occurs

A

$$289.8 \mu m$$

B

$$28.98 \mu m$$

C

$$0.2898 \mu m$$

D

$$0.002898 mm$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 73

Report

Air at 293 is flowing with velocity of 3m/s over a heated flat square plate. Plate is 0.3 m wide and is maintained at 330 K. Average heat loss from the plate due to convection is (Take $$v = 16.768E-6 m^2/s, Pr = 0.7, k = 0.027 W/m K$$)

A

33 W

B

37 W

C

45 W

D

41 W

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 74

Report

Twofluids A and B exchange heatin counterflow heat exchanger. Fluid A enters at 700 K and fluid B enters at 300 K. Mass flow rate of A & B is 1 kg/s. Specific heat of fluid A and B is 1000 J/kg K and 4000 J/kg K. Net Effectiveness of heat exchange is 75 %. Exit temperature of Fluid B is

A

380 K

B

385 K

C

375 K

D

370 K

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 75

Report

If the following equations are consistent, then value of k is
4x - 3y + 1 = 0
kx - 8y + 10 = 0
x + y - 5 = 0

A

-6

B

7

C

6

D

-7

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 76

Report

If $$\omega$$ and $$\omega^2$$ are cube roots of unity, then $$(2 - \omega + 2 \omega^2)(2 + 2 \omega - \omega^2)$$ is

A

0

B

-9

C

8

D

9

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 77

Report

Area of the ellipse $$\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1$$

A

ab

B

$$\frac{a}{b}$$

C

$$\pi ab$$

D

$$\frac{ab}{\pi}$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 78

Report

find $$\lim_{x \rightarrow 0} \frac{1 - \cos x}{x^2}$$

A

0

B

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

C

$$\frac{-1}{2}$$

D

1

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 79

Report

Equation of the plane parallel to the x axis and passes through the point (4,6,2) and (4, -5, 3)

A

$$y + 11 z + 28 = 0$$

B

$$y - 11 z + 28 = 0$$

C

$$y + 11 z - 28 = 0$$

D

$$y - 11 z - 28 = 0$$

View Solution

ISRO Scientist or Engineer Refrigeration & Air-Conditioning 2014 - Question 80

Report

$$\overline{a}$$ and $$\overline{b}$$ are vectors such that $$2 \overline{a} - 4 \overline{b}$$ and $$10 \overline{a} + 8 \overline{b}$$ are perpendicular to each other. Angle between the vectors $$\overline{a}$$ and $$\overline{b}$$ is

A

$$90^\circ$$

B

$$120^\circ$$

C

$$110^\circ$$

D

$$100^\circ$$

View Solution