Consider a 1.25 cm diameter carbon steel (1% C, k = 40 W/m-K) sphere to be cooled from 500oC to 100oC by a cooling air flow at 25oC with convection coefficient of 110 W/m2-K.
a) Determine the time required.
b) Determine the instantaneous heat transfer rate 2 minutes after the start of cooling.
c) Estimate the total energy transferred from the sphere during first 2 minutes.