An athlete cools down after a vigorous workout as sweat (mostly water) evaporates from their skin.
Which molecules escape from the sweat and what happens to the average kinetic energy of the water molecules that remain on the skin?
Escaping molecules: the less energetic ones. Average kinetic energy of remaining water molecules: decreases.
Escaping molecules: the less energetic ones. Average kinetic energy of remaining water molecules: increases.
Escaping molecules: the more energetic ones. Average kinetic energy of remaining water molecules: decreases.
Escaping molecules: the more energetic ones. Average kinetic energy of remaining water molecules: increases.
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.