ive been working on this problem and i have a solution too, but it doenst work. the reason i know that it doesnt work is because we have to submit our answers to a computer system that tells us if our answer is right or wrong. please help? A blackened, solid copper sphere of radius 5.70 cm hangs in a vacuum in an enclosure whose walls have a temperature of 21.0°C. If the sphere is initially at 0.0°C, find the rate at which its temperature changes, assuming that heat is transferred by radiation only. Also assume that the sphere has an emissivity of 1. here is what i did: Pnet = dQ/dt = mc dT/dt one two skip a few and... dT/dt = [3eσ(T^4 – T0^4)]/rρc its right...but it doenst work! please help?