Two identical copper flasks, P P\,P and QQQ, are filled with equal volumes of hot water at 90∘C90^{\circ}\text{C}90∘C and left to cool in a draft-free room at 18∘C18^{\circ}\text{C}18∘C. Flask P P\,P has a dull, matte black surface, whereas flask Q Q\,Q has a highly polished, shiny chrome surface.
Explain why the temperature of the water in flask P P\,P decreases at a faster initial rate than the temperature of the water in flask QQQ.
7 exam-style questions on Edexcel GCSE Physics 5.3 Black body radiation (physics only). Each one has a worked solution and a mark scheme showing where the marks go.