A solid aluminium ball, when quenched in a water bath maintained at 40°C, cools down from 550°C to 450°C in 20 seconds. The expected temperature of the ball after next 20 seconds may be about __________ °C.
370
340
320
300
Correct Answer :
A. 370
Related Questions
In fluid flow, and heat and mass transfer, one encounters (i) kinematic velocity (μ), (ii) molecular diffusivity (θ) and thermal diffusivity (α). The units of these quantities are.
μ , α and θ all have units of m/s
μ , α and θ all have units of m2/s
α and θ have units of m2/s, while μ has unit of m/s
α and θ have units of m/s, while μ has unit of m2/s
Carbide tipped cutting tools are manufactured by powder metallurgy techniques and have a composition of
90% tungsten carbide and 10% cobalt
70% aluminium oxide & 30% silica
30% nickel, 15% chromium & 55% tungsten
65% tungsten & 35% zirconium
Wrought iron is not
Ductile & resistant to corrosion/rusting
Weldable easily
Having uniform strength in all directions
Having maximum tensile strength along the lines of slag distribution
While the thermosetting polymers are amorphous in nature, the thermoplastic polymers are either amorphous or crystalline. The crystalline polymers are characterised by the
Low impact strength
High flexibility
Better finish and surface appearance
High plastic deformation
Which of the following materials has the least scrap value?
Aluminium
Stainless steel
Brass
Copper
Venturimeter is used to measure the flow rate of fluids in pipes, when the pipe is in __________ position.
Horizontal
Vertical
Inclined
Any
at 1173E; at equilibrium, what will be the number of moles of CO gas required to reduce one mole of 
at 1173 K?
1.0
1.3
2.3
3.3
Which of the following varies as the square root of oil pressure during atomisation of fuel oil through a pressure jet burner?
Output & fineness
Velocity
Both (A) & (B)
None of these
Common salt is produced from sea water in India generally by the __________ method.
Freeze drying
Solar evaporation
Electrolytic
None of these
Which of the following is not used as a bearing material?
Copper-lead alloys
Babbitts
Bronzes
Cermets
Maximum change in the hardness of martensite occurs in the carbon content range of __________ percent in steel.
0.01 to 0.10
0.2 to 0.4
0.5 to 0.7
0.8 to 1.0
Maximum permissible sulphur content in steel is __________ percent.
0.015
0.055
0.505
0.805
Electrical conductivities of semi-conductors are of the order of __________ ohm/cm.
10-3
103
10-15
1015
Cold chisels hammers are made of
High speed steel
High carbon steel
Forged steel
Mild steel
__________ fluid force is not considered in the Navier-Stokes equation.
Turbulent
Viscous
Gravity
Pressure
Pick out the correct statement about the condensation.
Filmwise condensation gives a lower heat transfer rate than the dropwise condensation
Suitable coating or vapour additive is used to promote film wise condensation
If a condensing liquid does not wet the surface dropwise, even then condensation will take place on it
Reynolds number of condensing liquid is based on its mass flow rate
The usual energy consumption in electric arc furnace steel making is __________ KWh/ton of steel.
60 - 100
400 - 700
1200 -1500
2000 - 2300
Steel containing low percentage of nickel, chromium & tungsten are termed as the __________ steel.
Wrought
Tool
Alloy
Plain carbon
Speed of a submarine in deep sea & that of an aeroplane is measured by a/an
Pitot tube
Hot wire anemometer
Rotameter
Stroboscope
If the demand for an item is trebled and the order cost is reduced to one third, then the economic order quantity
Is trebled
Remains unchanged
Decreases by a factor of 3
Decreases by a factor of 1/3
Titanium is produced by __________ of Ti Cl4.
Electrolytic reduction
Calcium reduction
Magnesium reduction
Thermal dissociation
Which of the following mainly decides the current to be employed is arc welding?
Electrode size
Plate thickness
Voltage across the arc
Welded portion length
Liquor poisoning generally occurs due to the presence of __________ in it.
Ethyl alcohol
Impurities
Methyl alcohol
Carbonic acid
__________ flux is used for the extraction of metal from its self fluxing ores.
No
Acid
Basic
Neutral
Pick out the wrong statement.
Copper is the metal having the highest electronic conductivity
Hardenability & Weldability of metals are inversely related
Covalent bonding formed by sharing of electrons is present in all semi-conductor materials
Glass transition temperature applies to 'polymers' but not to 'glasses'
Cupola produces __________ iron.
Pig
Cast
Wrought
Carbon free
Strain hardening effect in metals subjected to cold working is due to the __________ mechanism.
Slip
Fracture
Winning
Dislocation
Age hardening is connected with
Babbitt metal
Gun metal
Stainless steel
Duralumin
Quartz is a __________ material.
Diamagnetic
Ferromagnetic
Ferroelectric
Piezoelectric
Which one is neutral in character?
N2O4
N2O
N2O5
N2O3