We have an $80-degreecupofcoffeeand$5-degree milk to pour into it. In order to get the highest temperature coffee drink possible, should the milk be poured into the coffee as soon as it is ready or just before drinking?

Which of the following affect the temperature of water poured from one container to another?

On average, the heat output of a pupil is $200W$. This means that the pupil releases $200J$ of energy into the medium every second. How much heat does the student give off to the class in $1\text{hour}$ ($60\text{minute}$)?

How much energy is released when two litres of $100$-degree water cools to $20$ degrees?

The power of the coffee pot is $1200W$. How long does it take to boil one litre of ${21}^{\circ }C$ water? Try it!

What is the temperature of the water obtained by mixing $0.4,\text{litres}$ of $20,\circ ,C$ water and $0.6,\text{litres}$ of $80,\circ ,C$ water?

In which case does it take more energy to heat a metal ball to the same temperature - when the ball is hanging on the end of a thread, or when it is floating on a base? Note that the base and the thread do not absorb energy.

Is it a good idea to use water as a heat transfer medium in heating systems?

Describe how the temperature of the heater stones changes when the stove is thrown into the sauna.

The picture shows the inside of a kiln for firing clay. Discuss what the thermal conductivity and heat capacity of the material inside such a kiln should be. Is the density of such a material rather high or rather low?