Satellites burn off during re-entry to earth's atmosphere, because of the
Combustion with air
Gravitational pull by earth
Friction with earth's atmosphere
Loss in weight of the satellite
Correct Answer :
C. Friction with earth's atmosphere
Related Questions
Which of the following materials has the poorest electrical conductivity?
Carbon
Aluminium
Silver
Stainless steel
Maximum permissible sulphur content in steel is __________ percent.
0.015
0.055
0.505
0.805
Super conduction in metals is observed at a temperature of __________ °K.
<100
>100
About 273
About 373
Dielectric
Is an electrical insulating material
Of low resistivity is preferred
Should have high thermal conductivity
Need not defy the corrosive action of chemicals
If the head is doubled in & centrifugal pump, the power required will increase in the ratio of
23
23/2
25/2
21/3
In a furnace with heating element temperature at 1700°C, the dominant mechanism of heat transfer will be
Conduction
Radiation
Natural convection
Forced convection
Parallel straight line pattern of temperature distribution for both hot and cold fluids is observed in case of heat exchanger of the type
Parallel flow with equal heat capacities
Counter flow with equal heat capacities
Counter flow with unequal heat capacities
Parallel flow with unequal heat capacities
The size of the tetrahedral void in the closest packing of atoms is __________ that of the octahedral void.
Equal to
Greater than
Less than
Either (A), (B) or (C); depends on the size of atom
Nusselt number/Biot number varies
Inversely with thermal conductivity
Directly with heat transfer co-efficient
Directly with thermal conductivity
Inversely with the dimension of the solid
Fatigue limit improvement by over stressing the metal by successively increasing the load is called coaxing. In fatigue failure, the material fails
Below the yield point
Above the yield point
Below the elastic limit
At the elastic limit
Increase in temperature, in general results in the
Decrease in the viscosities of both liquids & gases
Increase in the viscosities of both liquids & gases
Increase in the viscosity of liquids and decrease in that of gases
Decrease in the viscosity of liquids and increase in that of gases
Pick out the wrong statement.
The X-rays cannot be deflected by electric field unlike cathode rays
The intensity of X-rays can be measured by ionisation current produced due to the ionisation of gas by X-rays
The quality of X-rays can be controlled by varying the anode-cathode voltage
Crystal structure of a material can be studied by an electron microscope
Solidification time of a molten metal in a casting is proportional to (where, V = volume of metal & A = its surface area; in the casting)
V/A
V/A2
V2/A
V2/A2
Copper deposits are found in India at the following location:
Kudremukh
Kolar
Khetri
Ramagundam
Even though heat transfer co-efficient in boiling liquids is large, use of fins is advantageous, when the entire surface is exposed to __________ boiling.
Film
Nucleate
Transition
All modes of
The best lubricants for a machine working at high temperature & load is
Grease
Solid lubricant
Animal oils
Mineral oils
Insulation of liquid surface can be achieved by __________ on top of its surface.
Floating hollow polypropylene spheres
Spraying alumina powder
Putting cement
None of these
A jet engine turbine blade is normally manufactured by
Forging
Shell moulding
Investment casting
Pressure die casting
A material in which the atoms are arranged regularly in some directions but not in others, is termed as 'mesomorphous material'; an example of which is
Lead
Glass
Mica
Silver
Shampoos are commercially not available in the form of
Powder
Gaseous mixture
Solution
Emulsion
Resistance of an electrical conductor is proportional to its (where, l = length and A = cross-sectional area of the conductor)
A
l
A2
Both 'a' & 'b'
Blow off cock is provided in steam boiler to
Guard the boiler in case of abnormal rise in steam pressure
Drain out water and sludge during its repair
Regulate the supply of water in boiler
Put out the fire in the furnace when the water level in the boiler falls to unsafe limit
The most abundant metal present in the earth's crust is;
Iron
Copper
Titanium
Aluminium
Which of the following metals cannot be hot worked at room temperature?
Zinc
Nickel
Lead
Tin
Which of the following performance characteristics of a S.I engine is not affected by the front end volatility of the petrol used?
Vapour locking
Hot starting
Spark plug fouling
All 'a', 'b' & 'c'
Which of the following emissions in the exhaust gas of an I.C. engine causes the formation of photochemical smog?
Nitrogen oxides
Hydrocarbons
Both 'a' & 'b'
Carbon monoxide
Consider the equilibrium A(g) + B(g) = AB(g). When the partial pressure of A is 10-2 atm, the partial pressure of B is 10-3 atm and the partial pressure of AB is 1 atm, the equilibrium constant 'K' is
10 atm-1
105 atm-1
10 (dimensionless)
105 (dimensionless)
On decreasing the grain size of a polycrystalline material, the property most likely to deteriorate is
Creep
Toughness
Tensile strength
Fatigue
__________ property of steel increases by addition of large amount of silicon in it.
Mechanical
Machining
Magnetic
Refractory
Speed of a submarine in deep sea & that of an aeroplane is measured by a/an
Pitot tube
Hot wire anemometer
Rotameter
Stroboscope