1
GATE ME 2004
MCQ (Single Correct Answer)
+1
-0.3
One dimensional unsteady state heat transfer equation for a sphere with heat generation at the rate $$'{q_g}',$$ can be written as
A
$${1 \over {r^2}}\,{\partial \over {\partial r}}\left( {r{{\partial T} \over {\partial r}}} \right) + {q \over k} = {1 \over \alpha }\,{{\partial T} \over {\partial t}}$$
B
$${1 \over {r^2}}\,{\partial \over {\partial r}}\left( {{r^2}{{\partial T} \over {\partial r}}} \right) + {q \over k} = {1 \over \alpha }\,{{\partial T} \over {\partial t}}$$
C
$${{{\partial ^2}T} \over {\partial {r^2}}} + {q \over k} = {1 \over \alpha }\,{{\partial T} \over {\partial t}}$$
D
$${{{\partial ^2}} \over {\partial {r^2}}}\left( {rT} \right) + {q \over k} = {1 \over \alpha }\,{{\partial T} \over {\partial t}}$$
2
GATE ME 2001
MCQ (Single Correct Answer)
+1
-0.3
In descending order of magnitude, the thermal conductivity of $$(a)$$ Pure iron, $$(b)$$ liquid water, $$(c)$$ saturated water vapour, and $$(d)$$ aluminum can be arranged as
A
$$a\,\,b\,\,c\,\,d$$
B
$$b\,\,c\,\,a\,\,d$$
C
$$d\,\,a\,\,b\,\,c$$
D
$$d\,\,c\,\,b\,\,a$$
3
GATE ME 1996
MCQ (Single Correct Answer)
+1
-0.3
For a given heat flow and for the same thickness, the temp drop across the material will be maximum for
A
Copper
B
Steel
C
Glass wool
D
Refractory brick
4
GATE ME 1994
MCQ (Single Correct Answer)
+1
-0.3
Two insulting materials of thermal conductivity $$K$$ and $$2K$$ are available for lagging a pipe carrying a hot fluid. If the radial thickness of each material is same
A
Material with higher thermal conductivity should be used for inner layer and one with lower thermal conductivity for the outer.
B
Material with lower thermal conductivity should be used for the inner layer and one with higher thermal conductivity for the outer.
C
It is immaterial in which sequence the insulating materials are used
D
It is not possible to judge unless numerical values of dimensions are given
GATE ME Subjects
Turbo Machinery
EXAM MAP