An athlete sweats while running on a warm, windy day. Why does the evaporation of sweat cause her skin to cool down?
The less energetic water molecules in the sweat escape into the air.
The sweat reacts chemically with the wind to create a cool barrier.
The more energetic water molecules in the sweat escape, decreasing the average kinetic energy of the remaining liquid.
The sweat does not evaporate quickly enough, which traps heat on the 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.