hmt mid sem paper

1Answer the following

What factors effect the thermal conductivity of insulating material?

For a given heat flow and for the same thickness, the temperature dropacross the material will be maximum for [GATE-1996](a) Copper (b) Steel (c) Glass-wool (d) Refractory brick

A steel ball of mass 1kg and specific heat 0.4 kJ/kg is at a temperatureof 60C. It is dropped into 1kg water at 20C. The final steady statetemperature of water is: [GATE-1998](a) 23.5C (b) 300C (c) 35C (d) 40C

In descending order of magnitude, the thermal conductivity ofa. Pure iron, [GATE-2001]b. Liquid water,c. Saturated water vapour, andd. Pure aluminium can be arranged as(a) a b c d (b) b c a d (c) d a b c (d) d c b a

Consider the following statements: [IES-1998]The Fourier heat conduction equation Q kA dTdx= presumes1. Steady-state conditions2. Constant value of thermal conductivity.3. Uniform temperatures at the wall surfaces4. One-dimensional heat flow.Of these statements:(a) 1, 2 and 3 are correct (b) 1, 2 and 4 are correct(c) 2, 3 and 4 are correct (d) 1, 3 and 4 are correct

Thermal diffusivity of a substance is: [IES-2006](a) Inversely proportional to thermal conductivity(b) Directly proportional to thermal conductivity(c) Directly proportional to the square of thermal conductivity(d) Inversely proportional to the square of thermal conductivity

Match List-I with List-II and select the correct answer using the codesgiven below the lists: [IES-1996]List-I List-IIA. Momentum transfer 1. Thermal diffusivityB. Mass transfer 2. Kinematic viscosityC. Heat transfer 3. Diffusion coefficientCodes: A B C A B C(a) 2 3 1 (b) 1 3 2(c) 3 2 1 (d) 1 2 3

In MLT system (T being time and temperature), what is thedimension of thermal conductivity? [IES-2009](a) ML T 1 1 3 (b) MLT1 1 (c) ML T1 3 (d) ML T 1 2

Heat flows through acomposite slab, as shownbelow. The depth of the slabis 1 m. The k values are inW/mK. the overall thermalresistance in K/W is:(a) 17. (b) 21.9(c) 28.6 (d) 39.2[GATE-2005