A bar of iron is 0.5m long, 0.2m wide and 0.1m high (which means its volume is 1.0 × 10−2m3 and its surface area is 3.4 × 10−1m2 ). Iron has a density of 7900 kg m3 , a heat capacity of 400 J kg◦C , and a coefficient of linear expansion of 1.2 × 10−5 . The bar of iron is initially at 600K. Assuming that the emissivity e = 0.8, what is the rate at which iron radiates energy after it has lost 8.0 × 106J? I know the answer is 220 W, but how do I get that answer? Thanks!