The best lubricants for a machine working at high temperature & load is
Grease
Solid lubricant
Animal oils
Mineral oils
Correct Answer :
B. Solid lubricant
Related Questions
The main constituent of bones is
CaF2
Ca3(PO4)2
CaCO3
CaCl2
The underground well of a biogas plant is called the
Septic tank
Oxidation well
Digestor
Lagoon
Euler number is defined as the ratio of inertia force to __________ force.
Pressure
Elastic
Gravity
Viscous
The co-ordination number in simple cubic structure is
4
6
8
12
A compact estimate about the amount of materials handling between various work stations is obtained from the
Gantt chart
Bin chart
String diagram
Travel chart
An approximately __________ process exemplifies the flow of a gas through a very long pipe of uniform cross-section.
Adiabatic
Isothermal
Isentropic
Isochoric
The property of material, by which a given amount of energy is absorbed by it, without plastic deformation, is called
Resilience
Toughness
Ductility
Impact strength
The ability of tool steel to resist softening at high temperatures is termed as __________ hardness.
Red
Extended
Super
Extreme
Metalloids
Are good conductor of heat & electricity
Act as electron donors with metals & as electron acceptor with non-metals
Are not necessarily solids at room temperature
Are compounds that exhibit both metallic & non-metallic properties to some extent and are exemplified by elements like germanium, silicon & boron
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
A psychrometer does not measure the __________ temperature of moist air.
Dew point
Dry bulb
Wet bulb
None of these
Cold chisels hammers are made of
High speed steel
High carbon steel
Forged steel
Mild steel
Solute atoms which cause yield point phenomenon in mild steel are/is
Aluminium
Boron
Carbon
Nitrogen
An abrupt and sudden fall in the reading of barometer is an indication of the
Storm
Rain
Clear weather
Cold wave
Probability of cavitation occuring becomes very high, when the local __________ resulting in water bubbles formation, which on rupture cause cavitation
Pressure falls below the vapour pressure
Pressure becomes very high
Temperature becomes low
All 'a', 'b' & 'c'
Normalising of an object does not
Refine coarse grain structure obtained during hot working
Improve ductility
Improve yield strength
Improve mechanical properties
Tin based white metals are used, where bearings are subjected to
High pressure & load
Low pressure & load
High temperature
Large surface wear
Nusselt number is related to Grashoff number (Gr) in turbulent & laminar flow respectively, in respect of free convection over a vertical flat plate as
Gr0.25, Gr
Gr0.25, Gr0.33
Gr, Gr0.25
Gr0.33, Gr0.25
Though tin occurs lower than iron in the electrochemical series, yet it is coated on steel for corrosion protection, because of its
Lower cost
Abundant availability
Resistance to vegetable acids as the tin plate are commercially used in 'canning' industry
None of these
Basic open hearth furnace (BOF) is not used for producing __________ steel.
Killed
Rimming
High alloy
None of these
Viscoelastic behaviour is observed in __________ materials.
Non-crystalline organic polymeric
Ceramic
All crystalline
All amorphous
Out of the following __________ iron has the best capability to bear sudden & excessive shocks.
White
Cast
Wrought
Pig
Reduction in the grain size reduces the __________ of the material.
Fatigue resistance
Tensile strength
Creep resistance
All (A), (B) & (C)
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 same volume of all gases is representative of their
Specific gravities
Densities
Gas characteristic constants
Molecular weights
Powder metallurgy is used to produce
High precision components with complex cavities and sharp features
Components of large size
Porosity free components
Components of such alloys whose constituents do not form alloys readily
Highest cutting speed is achieved by the __________ tool material.
High speed steel
Carbide
Cast alloy
Plain carbon steel
The dew point temperature lines on psychrometric charts are straight inclined sloping downwards to the right. When relative humidity of moist air is 100%, then
Wet bulb temperature=dry bulb temperature
Wet bulb temperature=dew point temperature
Saturation temperature=dew point temperature
All 'a', 'b' & 'c'
__________ joint is usually used for joining cast iron pipes mostly used for temporary pipelines, where it may be necessary to dismantle & reassemble the pipeline very frequently.
Collar
Flanged
Bell and Spigot
Expansion
A steam carrying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted will
Increase
Decrease
Remain unaffected
May increase or decrease; depends on the thickness of each layer