A copper bar 2.5 m long has a circular cross section of radius 2 cm. One end is kept at 80oC and the other end is kept at 0oC. The surface of the bar is insulated so that there is negligible heat loss through it. If kcopper 401 Wm-1K-1, what is the temperature of the bar 25 cm from the hot end?
under steady state, heat flow rate same through all sections Q watt - k A [80 - 0] / [0 - 2.5] . entire rod let temperature at section 0.25 m away t for given length Q1 watt - k A [80 - t] / [0 - 0.25] steady state Q Q1 [80 - t] / [0 - 0.25] [80 - 0] / [0 - 2.5] ---------------------------- temperature gradients are equal [80 - t]/0.25 80/2.5 80 - t 8 t 72 deg C
