The passenger section of an airplane can be thought to have a shape of a cylindrical tube. For a small airplane, the tube is 35 m long and has an inner radius of 2.5 m. The exterior of the tubular wall is lined up with a 6- cm thick layer of insulating material of thermal conductivity 4 X 10-5 cal/s- cm-K. If the inside temperature is to be maintained at 25 °C, and the outside temperature is -35 °C, determine the rate that heat must be delivered to maintain this temperature difference.
The Attempt at a Solution
dQ/dt = kA(T(inside) - T(outside))/l
I a having trouble identifying y variables
k = 4E^-5, A = this is my confusion, is it the cross-sectional area of the inside or outside of the plane, l = .006 m