A 3-m-long steel rod (k = 43 W/(mK), = 1.17 105 m2/s) is initially at

Question:

A 3-m-long steel rod (k = 43 W/(mK), α = 1.17 \ 10–5 m2/s) is initially at 20°C and insulated completely except for its end faces. One end is suddenly exposed to the flow of combustion gases at 1000°C through a heat transfer coefficient of 250 W/(m2 K) and the other end is held at 20°C. How long will it take for the exposed end to reach 700°C? How much energy will the rod have absorbed if it is circular in cross section and has a diameter of 3 cm?
GIVEN
Steel rod with one end at fixed temperature and the other end exposed to combustion gases