A copper sphere with density 8900 kg/m3, radius 5.00 cm, and emissivity e = 1.00 sits on an insulated stand. The initial temperature of the sphere is 300 K. The surroundings are very cold, so the rate of absorption of heat by the sphere can be neglected. a. How long does it take the sphere to cool by 1.00 K due to its radiation of heat energy? Neglect the change in heat current as the temperature decreases.
b. To assess the accuracy of the approximation used in part A, what is the fractional change in the heat current H when the temperature changes from 300 K to 299 K?