Q.1
From the concept of kinetic theory, mean travel velocity of the gas molecules is prescribed by the relation
  • a) V = (3M/GT) 1/2
  • b) V = (3GT/M) 1/2
  • c) V = (6T/GM) 1/2
  • d) V = (3GT/2M) 1/2
Q.2
Low temperature insulation are used when the enclosure is at a temperature lower than the ambient temperature. Which one of the following is not a low temperature insulation?
  • a) Asbestos
  • b) Cork
  • c) Cattle hair
  • d) Slag wool
Q.3
The value of Lorenz number in 10-8 W ohms/K2 is
  • a) 2.02
  • b) 2.35
  • c) 2.56
  • d) 2.45
Q.4
For liquids, thermal conductivity is governed by the relation
  • a) k = A c p p7/3/M1/3
  • b) k = 2A c p p4/3/M2/3
  • c) k = A c p p4/3/M1/3
  • d) k = A c p p8/3/M1/3
Q.5
Consider the following parameters
  • a) i and ii
  • b) i, ii, iii and iv
  • c) i and iii
  • d) i, ii and iii
Q.6
The thermal conductivity and the electrical conductivity of a metal at absolute temperature are related as
  • a) k/σ T
  • b) k/σ
  • c) k σ/T
  • d) k/T
Q.7
The relation Ϫ2 t =0 is referred to as
  • a) Poisson’s equation
  • b) Fourier heat conduction equation
  • c) Solution for transient conduction
  • d) Laplace equation
Q.8
The unit of thermal diffusivity is
  • a) m2/hr-K
  • b) kcal/m2-hr
  • c) m2/hr
  • d) m/hr-K
Q.9
To effect a bond between two metal plates, 2.5 cm andcm thick, heat is uniformly applied through the thinner plate by a radiant heat source. The bonding must be held atK for a short time. When the heat source is adjusted to have a steady value of 43.5 k W/ma thermocouple installed on the side of the thinner plate next to source indicates a temperature ofK. Calculate the temperature gradient for heat conduction through thinner plate. In the diagram, the upper plate is 2.5 cm thick while the lower iscm thick.
Questionheat-transfer-questions-answers9.jpg
  • a) – 1000 degree Celsius/m
  • b) – 2000 degree Celsius/m
  • c) – 3000 degree Celsius/m
  • d) – 4000 degree Celsius/m
Q.10
The diffusion equations
  • a) Temperature doesn’t depends on time
  • b) There is no internal heat generation
  • c) Steady state conditions prevail
  • d) There is no internal heat generation but unsteady state condition prevails
0 h : 0 m : 1 s