Heat Transfer

JKSSB Junior Engineer (Mechanical) · Technical Subjects (Mechanical) · 11 practice questions with answers and explanations: 4 Easy, 7 Medium, 0 Hard.

Sample questions

Sample Easy question 1

Which of these materials has the highest thermal conductivity?

  1. Air
  2. Wood
  3. Copper
  4. Glass wool
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Answer: C. Metals conduct heat much better than insulators.

Sample Easy question 2

The three modes of heat transfer are:

  1. Conduction, convection and radiation
  2. Absorption, reflection and transmission
  3. Fusion, evaporation and sublimation
  4. Conduction, compression and expansion
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Answer: A. Heat moves by contact, by fluid motion, or as electromagnetic waves.

Sample Easy question 3

Fourier's law relates heat flow to:

  1. The velocity gradient
  2. The concentration gradient
  3. The temperature gradient
  4. The pressure gradient
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Answer: C. q = −k (dT/dx).

Sample Medium question 4

The Biot number is the ratio of:

  1. Convection to conduction
  2. Buoyancy to viscous force
  3. Inertia to viscous force
  4. Internal conduction resistance to external convection resistance
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Answer: D. A small Biot number means the temperature inside the body is nearly uniform.

Sample Medium question 5

The purpose of fins on a surface is to:

  1. Increase the heat transfer area
  2. Reduce the surface temperature of the fluid
  3. Reduce conduction
  4. Increase insulation
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Answer: A. More surface area increases the rate of heat dissipation.

Sample Medium question 6

The Prandtl number is the ratio of:

  1. Momentum diffusivity to thermal diffusivity
  2. Convection to conduction
  3. Inertia force to viscous force
  4. Thermal diffusivity to momentum diffusivity
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Answer: A. Pr = μ·Cp / k.

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