Two identical cups containing equal volumes of water sit on a table. One starts at a temperature of $50 °\mathrm{C}$ and the other at $40 °\mathrm{C}$. State which will cool fastest. Explain your answer.

Imagine you've just made a cup of coffee when someone phones you. You know this conversation will take some time. Using your knowledge of thermal radiation and specific heat capacity, decide, and then explain, whether you should put your milk in before you answer the phone or after, so that the coffee is hottest when you drink it.

The heat sink around the processor in a computer is often piece of aluminium. It is needed to remove thermal energy from the processor whilst the processor is in operation. State and explain two design features that make it an effective emitter of thermal radiation, to allow the processor to remain cool enough to function properly.