Cooling of a black body in vacuo a thin black body of very high thermal conductivity has a volume V, surface area A, density p, and heat capacity Cp. At time t = 0, this body at temperature T1 is placed in a black enclosure, the walls of which are maintained permanently at temperature T₂ (with T₂ < T1). Derive an expression for the temperature T of the black body as a function of time.