An athlete is covered in sweat after a race on a warm afternoon. When they stand in front of an electric fan, they immediately feel cold. Why do they feel cold even though the air is warm?
The less energetic sweat molecules on their skin escape quickly.
The more energetic sweat molecules do not escape quickly from their skin.
The sweat on their skin does not evaporate quickly enough to keep them warm.
The sweat on their skin evaporates quickly under the airflow, cooling their skin.
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.