A block of material with a cross-sectional area of 15 cm2 and length of 8.0 cm is at hand. A temperature difference of 30°C is established and maintained across the block. Find the rate of heat flow through it if:
a. The material is copper (K = 397 Js-1 m -1C -1 ).
b. The material is air (K = 0.0234 Js-1 m -1C -1 ).
c. The material is wood (K = 0.08 Js-1 m -1C -1 ).