A hot iron block at 300 ºC of sides 15 cm by 20 cm by 25 cm is placed on insulated horizontal surface with its 15 cm side oriented vertically. There is negligible heat loss from the bottom surface of the block. Calculate the heat loss from the block's five surfaces by free convection to the surrounding quiescent air at atmospheric pressure and 25 ºC. Break the problem into 4 vertical surfaces and one horizontal surface.