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Current Affairs January 2024

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4

Solidification time of a molten metal in a casting is proportional to (where, V = volume of metal & A = its surface area; in the casting)

A. V/A

B. V/A2

C. V2/A

D. V2/A2

Correct Answer :

D. V2/A2


Related Questions

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4

Spherical shape of mercury droplets is due to its

A. High viscosity

B. Low surface tension

C. High density

D. High surface tension

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4

Routing in production, planning & control is concerned with the

A. Sequence of operation to be performed

B. Progress of work performed

C. Authorisation of work to be performed

D. Balancing of load on machines

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4

In a good rimming steel

A. Carbon and silicon should be low

B. Silicon should be low but carbon should be high

C. Both silicon & carbon should be high

D. Silicon should be high but carbon should be low

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4

Pick out the wrong statement.

A. Geothermal energy is a non-conventional source of energy

B. Mass is converted into energy in both nuclear fission & fusion reaction

C. Inhalation of mercury vapour is not harmful for human beings

D. Inhalation of arsenic causes cancer

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4

Unit of viscosity in CGS system is

A.

B.

C.

D.

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4

__________ metal is used as a bearing liner material.

A. Pewter

B. White

C. Babbitt

D. Gun

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4

Principal alloying element in Elinvar (used for making hair springs for watches) is

A. Copper

B. Aluminium

C. Nickel

D. Zinc

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4

Ammonia leakage in the refrigeration system is detected by

A. Sulphur stick, which on detection gives white smoke

B. Using chemical reagents

C. Its smell

D. Soap solution

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4

Uniform ramming of sand in green sand moulding process leads to

A. Reduced chance of gas porosity

B. Greater dimensional stability of the casting

C. Uniform flow of molten metal into the mould cavity

D. Less sand expansion type of casting defect

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4

LVDT used for displacement measurement is a/an __________ transducer.

A. Passive

B. Active

C. Capacitive

D. None of these

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4

Which of the following gases cause global warming?

A. Carbon monoxide

B. Carbon dioxide

C. Nitrogen

D. Ozone

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4

Specific gravity of a metal, which weighs 5 kg in air and 4 kg when submerged in water, will be

A. 5

B. 1.25

C. 2.5

D. 3.75

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4

Two wires of the same radius & material having length in the ratio of 1 : 2 are stretched by the same force. The strain produced in the two wires will be in the ratio of

A. 1 : 1

B. 1 : 2

C. 2 : 1

D. 1 : 4

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4

With increase in impurities in metals, their corrosion resistances

A. Increase

B. Decrease

C. Remain same

D. May increase or decrease; depending on the type of metal

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4

__________ is used for tying the steel columns to concrete foundation.

A. Grouting

B. Eyebolt

C. Anchor bolts

D. Refractory castables

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4

During sensible heating of humid air

A. Relative humidity increases

B. Dew point remains constant

C. Dry bulb & wet bulb temperature increases

D. Both 'b' & 'c'

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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

The pressure outside a bubble/droplet of liquid is __________ the internal pressure.

A. Greater than

B. Less than

C. Equal to

D. Unpredictable; depends on the bubble size

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4

The effect of friction on the flow of steam through a nozzle is to decrease the __________ of steam.

A. Wetness

B. Mass flow rate

C. Both 'a' & 'b'

D. Neither 'a' nor 'b'

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4

Blasting of tri-nitro-toluene (TNT) is done by mixing it with ammonium

A. Nitrate

B. Sulphate

C. Carbonate

D. Chloride

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4

Cobalt - 60 is used as a source of __________ in medical therapy & industrial radiography.

A. X-rays

B. γ-rays

C. α-rays

D. β-rays

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4

Good design of the casing of a centrifugal pump aims at minimising the

A. Cavitation

B. Frictional losses

C. Kinetic energy loss

D. Static head

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4

The main constituent of bones is

A. CaF2

B. Ca3(PO4)2

C. CaCO3

D. CaCl2

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4

Pick out the wrong statement about coating/electroplating of metals.

A. Phosphate coating is used as an excellent base for paints & enamels

B. Phosphate coating is less corrosion resistant than chromate coating

C. The base metal to be electroplated is normally made the cathode of the electrolytic cell and coating metal is made the anode

D. Calorising is the process of coating steel with chromium

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4

Tesla metre per ampere (T. m/A) is the unit for the measurement of

A. Magnetic susceptibility

B. Magnetic moment

C. Permeability of free space

D. Flux density

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4

Notched bar test is used for testing the __________ of a material.

A. Impact strength

B. Endurance limit

C. Machinability

D. Corrosion resistance

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4

Steel balls are manufactured by

A. Sintering

B. Casting

C. Cold heading

D. Spinning

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4

Pick out the wrong statement.

A. Ductile fracture of a stressed material, which exhibits a large plastic deformation is commonly caused by the formation and coalescence of voids in the necked region

B. Brittle fracture is caused by the propagation of pre-existing cracks in the material and involves minimum plastic deformation

C. Fatigue fracture of a material is always brittle in nature and takes place due to the existence of line imperfections

D. Brittle materials are generally tested in tension

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4

Lead pencil contains

A. Graphite

B. Lead sulphide

C. Lead

D. Both (B) & (C)

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4

Cold heading or upsetting is categorised as the __________ process.

A. Extrusion

B. Bending

C. Rolling

D. Forging