Answer:
the heat transfer from the pipe will decrease when the insulation is taken off for r₂< 
where;
r₂ = outer radius
= critical radius
Explanation:
Note that the critical radius of insulation depends on the thermal conductivity of the insulation k and the external convection heat transfer coefficient h .

The rate of heat transfer from the cylinder increases with the addition of insulation for outer radius less than critical radius (r₂<
) 0, and reaches a maximum when r₂ =
, and starts to decrease for r₂<
. Thus, insulating the pipe may actually increase the rate of heat transfer from the pipe instead of decreasing it when r₂<
.
Answer: False
Explanation: Sandwich materials are usually in composite material form which has a fabrication of two thin layers which are stiff in nature and have light weighing and thick core .The construction is based on the ratio that is of stiffness to the weight .Therefore, the density of the material in the core is not high and are only connected with the skin layer through adhesive .So the given statement is false that sandwich materials typically use a high density core with non- structural cover plates.
Answer:
Explanation:
a) the steady-state, 1-D incompressible and no energy generation equation can be expressed as follows:

b) For a transient, 1-D, constant with energy generation
suppose T = f(x)
Then; the equation can be expressed as:

where;
= heat generated per unit volume
= Thermal diffusivity
c) The heat equation for a cylinder steady-state with 2-D constant and no compressible energy generation is:

where;
The radial directional term =
and the axial directional term is 
d) The heat equation for a wire going through a furnace is:
![\dfrac{\partial ^2 T}{\partial z^2} = \dfrac{1}{\alpha}\Big [\dfrac{\partial ^2 T}{\partial ^2 t}+ V_z \dfrac{\partial ^2T}{\partial ^2z} \Big ]](https://tex.z-dn.net/?f=%5Cdfrac%7B%5Cpartial%20%5E2%20T%7D%7B%5Cpartial%20z%5E2%7D%20%3D%20%5Cdfrac%7B1%7D%7B%5Calpha%7D%5CBig%20%5B%5Cdfrac%7B%5Cpartial%20%5E2%20T%7D%7B%5Cpartial%20%5E2%20t%7D%2B%20V_z%20%5Cdfrac%7B%5Cpartial%20%5E2T%7D%7B%5Cpartial%20%5E2z%7D%20%5CBig%20%5D)
since;
the steady-state is zero, Then:
'
e) The heat equation for a sphere that is transient, 1-D, and incompressible with energy generation is:
