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, covering 5.3.1 Emission of radiation and temperature, 5.3.2 Radiation balance and constant temperature, and 5.3.3 The temperature of the Earth. Each one has a worked solution and a mark scheme showing where the marks go.