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4

One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m- 1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is

A. 100

B. 900

C. 9000

D. 10000

Correct Answer :

D. 10000


Related Questions

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4

With decrease in the grain size of a material, its creep resistance

A. Increases

B. Decreases

C. Remain constant

D. Either (A) or (B); depends on the material

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4

Which of the following is not a characteristic observed in material failure by fatigue fracture?

A. Plastic deformation of material does not occur

B. Initiation of crack from below the surface does not occur

C. Initiation of crack occurs on the surface of the machine part

D. Presence of both rough & smooth zone with conchoidal markings in smooth zone of the surface

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4

Nickel is a __________ material.

A. Ferromagnetic

B. Semi-conductor

C. Paramagnetic

D. Ferroelectric

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4

Which of the following is an unconventional source of energy?

A. Thermal power

B. Hydroelectric power

C. Nuclear-fusion power

D. Solar power

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4

Which of the following processes follows the hardening process for reducing the hardening strains & increasing the toughness of the steel part?

A. Anodising

B. Tempering

C. Carburising

D. Annealing

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4

Diamagnetic materials

A. Are magnetised by eddy currents only

B. Are non-magnetic and cannot be magnetised

C. Are magnetised in direction opposite to the magnetic field

D. Can be magnetised in one direction only

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4

Breakeven point represents the condition, when the company runs under no profit no loss condition. In break even analysis, total cost comprises of fixed cost

A. Only

B. Plus variable cost

C. Plus overhead cost

D. Plus selling expenses

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4

A gas which is collected over water becomes moistened due to water vapor, exerts its own partial pressure at the gas temperature, which is termed as its

A. Aqueous tension

B. Saturated humidity

C. Vapor pressure

D. Absolute humidity

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4

The softness or hardness of a grinding wheel depends upon the type & amount of bonding material used. For general purpose cutter grinding __________ grinding wheel is normally used.

A. Hard

B. Soft

C. Silicon carbide

D. Aluminium oxide

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4

Super conduction in metals is observed at a temperature of __________ °K.

A. <100

B. >100

C. About 273

D. About 373

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4

For dynamic strain measurement, the Wheatstone bridge used is of __________ type.

A. Voltage sensitive null

B. Voltage sensitive deflected

C. Current sensitive deflected

D. None of these

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4

Compressed dry air is used as the cutting fluid, while machining

A. Steel

B. Cast iron

C. Aluminium

D. None of these

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4

The most economical channel section for the fluid flow is the one for which the discharge is maximum for a given cross-sectional area. Vertical velocity distribution in an open channel for laminar flow can be assumed to be

A. Parabolic

B. Hyperbolic

C. Straight line

D. None of these

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4

Pick out the wrong statement about the machinability of metals. Machinability of a metal

A. Decreases with increase in strain hardening tendencies

B. Decreases with increase in hardness, in general

C. Depend on the composition, microstructure and physical & mechanical properties

D. Decreases with increases in tensile strength & decrease in grain size

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4

The laminar boundary layer thickness in zero pressure gradient flow over a flat plate along the x-direction varies as x0.5 while the thickness of turbulent boundary layer varies as (where, x = distance from the leading edge)

A. x1.5

B. x0.8

C. x-1.5

D. x-0.8

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4

Fibrous fracture is normally encountered in the __________ materials.

A. Hard

B. Elastic

C. Ductile

D. Brittle

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4

In the Bayer's process, bauxite is digested under pressure using

A. H2SO4

B. NaOH

C. NH3

D. HCl

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4

Otto cycle used in spark ignition petrol engines is also known as the constant __________ cycle.

A. Volume

B. Pressure

C. Heat

D. None of these

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4

Wavelength of radiation emitted by a body depends on the __________ of its surface.

A. Temperature

B. Area

C. Nature

D. All 'a', 'b' & 'c'

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4

A polymer is termed as an 'elastomer', if its percentage elongation is more than 100%. An elastomer is termed as 'rubber' if its percentage elongation is more than __________ percent.

A. 150

B. 200

C. 300

D. 400

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4

Coating thickness in case of galvanising of steel sheet generally corresponds to the deposition of __________ gms of zinc per of steel strip.

A. 5-10

B. 1000-1500

C. 120-500

D. 1500-3000

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4

Limestone is added in the blast furnace (during pig iron manufacture) to

A. Form slag by combining with impurities

B. Supply heat by undergoing exothermic reaction with impurities

C. Reduce the coke consumption

D. Reduce slag viscosity

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4

The product of a commercial direct reduction process is

A. Liquid iron

B. Solid iron

C. Sponge iron

D. Iron saturated with carbon

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4

Cementite is in the lamellar form in the __________ phase of steel.

A. Martenistic

B. Bainitic

C. Pearlitic

D. Ferritic

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4

Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity)

A. 1/k

B. k

C. k2

D. 1/k2

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4

Which of the following metals cannot be hot worked at room temperature?

A. Zinc

B. Nickel

C. Lead

D. Tin

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4

__________ is not used as the control rod material in a nuclear reactor.

A. Cobalt

B. Hafnium

C. Cadmium

D. Boron

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4

What is the pH of distilled water?

A. 0

B. 1

C. 7

D. 14

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4

Silicon percentage in the silicon steel used for electrical appliances/equipments is

A. 0.3-0.4

B. 12-14

C. 3-4

D. 20-25

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4

__________ test is the appropriate test to determine whether a material is ductile or brittle.

A. Impact

B. Cupping

C. Hardness

D. Tensile