Related Questions

Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the
A Surrounding temperature
B Average temperature of the fin
C Temperature of the fin end
D Constant temperature equal to that of the base
Heat transfer by radiation from a hot body will be most rapid, if its surface is __________ because of its higher emissivity.
A White & rough
B Black & rough
C White & polished
D Black & polished
Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of
A Graphite powder
B Thoria
C Zircon powder
D Beryllium
The cutting speed for drilling aluminium, brass and bronze with carbon steel drills is _________ cutting speed for drilling mild steel with high speed steel drills.
A Equal to
B Less than
C More than
D None of these
The scales form in heat exchanges after a period of operation and provide additional resistance to heat transfer with some heat transfer coefficient . The reciprocal of this scale heat transfer coefficient is called .
A scaling factor
B forming factor
C resisting factor
D fouling factor
For machining a mild steel workpiece by a high speed steel tool, the average cutting speed is
A 5 m/min
B 10 m/ min
C 15 m/min
D 30 m/min
The allowable tensile stress in structural mild steel plates for steel tank is assumed as
A 95.0 MPa on net area
B 105.5 MPa on net area
C 105.5 MPa on gross area
D 150.0 MPa on gross area
The average cutting speed for turning mild steel with a high speed steel tool is
A 15 to 19 m/min
B 25 to 31 m/min
C 60 to 90 m/min
D 90 to 120 m/min
Mild steel is a/an __________ steel.
A Low carbon
B Medium carbon
C High carbon
D High alloy
With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer
A Decreases
B Increases
C Increases exponentially
D Remains unaffected

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