Two identical cans contain equal masses of water and have different surface finishes. Both start at 75 ∘C75\,^\circ\mathrm{C}75∘C. After 5.0 min, the matt black can is at 65 ∘C65\,^\circ\mathrm{C}65∘C and the shiny can is at 71 ∘C71\,^\circ\mathrm{C}71∘C.
What is the ratio of their mean rates of temperature decrease, matt black to shiny?
5:25:25:2
2:52:52:5
65:7165:7165:71
71:6571:6571:65
96 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.