The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc.

In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of

A

Relative roughness

B

Absolute roughness

C

Friction co-efficient for flows at equal Reynold number

D

All of the above

In a class of 60 students, 20 students like Math, 25 students like English and 30 students like Science. If 5 Students like both Math and Science, 8 Students like both English and Science and 3 students like neither of these subjects, how many students like all of the three subjects?

A

2

B

3

C

4

D

5

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

Which of the following loss in a D.C. generator is dissipated in the form of heat?

A

Mechanical loss

B

Core loss

C

Copper loss

D

All of the above

By which of the following methods major portion of the heat generated in a H.R.C. fuse is dissipated ?

A

Radiation

B

Convection

C

Conduction

D

All of the above

Which of the following losses is not dissipated by the stator core surface in a synchronous motor ?

A

Eddy current losses in the conductors

B

Iron losses in the stator

C

Copper losses in the slot portion of the conductors

D

Windage losses

Design of waste heat boiler for recovery of waste heat from furnace gases depends upon the

A

Quantity & temperature of waste gas

B

Dust concentration & nature of dust in waste gas

C

Corrosive nature of the waste gas

D

All of the above

The rate of heat transfer from a vertical plate by natural convection depends upon the temperature differences (ΔT) between wall and outside bulk. The proportionality is given as

A

$${\left( {\Delta {\text{T}}} \right)^{\frac{1}{4}}}$$

B

$${\left( {\Delta {\text{T}}} \right)^{\frac{1}{2}}}$$

C

$${\left( {\Delta {\text{T}}} \right)^{\frac{5}{4}}}$$

D

$${\left( {\Delta {\text{T}}} \right)^{\frac{3}{4}}}$$

Efficiency of a heat engine working on Carnot cycle between two temperature levels depends upon the

A

Two temperatures only

B

Pressure of working fluid

C

Mass of the working fluid

D

Mass and pressure both of the working fluid

In machining metals, surface roughness is due to

A

feed marks or ridges left by the cutting tool

B

fragment of built up edge on the machined surface

C

cutting tool vibrations

D

all of the mentioned

The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc.

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