A solid spherical shell with a 12.0 cm inner radius and 15.0 cm
outer radius is filled with water.
A heater inside the water maintains the water at a constant
temperature of 350 K. The outer
surface of the shell is maintained at 280 K. The shell is made of
Portland cement, which has a
thermal conductivity of 0.29 W/(mK).
(a) Starting from the basic equation for thermal conduction, derive
the rate at which heat flows
out of the water....