Related Questions

The heated parts of an electrical machine dissipate heat into their surroundings by which of the followingmodes of heat dissipation ?
A Conduction
B Convection
C Radiation
D All of the above
3N ও 2N মানের দুইটি বলের লদ্ধি R । প্রথম বলের মান দ্বিগুণ করলে লদ্ধির মানও দ্বিগুণ হয়। বলদ্বয়ের মধ্যবর্তী কোণের মান হবে- (The resultant of two forces 3N and 2N is R. If the first force is doubled then the resultant is also doubled. The angle between the forces is-)
A 30°
B 45°
C 65°
D 120°
For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus-Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of
A 1
B 1.74
C 6.1
D 37
Which device maintains a body at a temperature lower than the temperature of the surroundings?
A PMM1
B PMM2
C refrigerator
D heat pump
Two forces of magnitude 3m and 2m respectively have a resultant R. if the first force is doubled, the magnitude of the resultant is doubled.Find the angle betuween forces?
A 90°
B 120°
C 135°
D 145°
Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because
A Convection becomes important
B Conduction becomes important
C Radiation becomes important
D Sub-cooled boiling occurs
The available energy of a system _____ as its temperature or pressure decreases and approaches that of the surroundings.
A remains constant
B increases
C decreases
D none
A hot liquid is kept in a big room. The logorithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an
A Ellipse
B Straight line
C Parabola
D Circular arc
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
The difference between a two-digit number and the number obtained by interchanging the digits is 36. What is the difference between the sum and difference of the digits of the number if the ratio between the digits the number is 1 : 2?
A 4
B 8
C 16
D 24

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