During a hot summer day, overhead power cables between two utility poles are observed to sag more than they do on a cold winter day. Why do the cables sag more in summer?
The cables expand due to the higher temperature in summer.
The cables contract due to the higher temperature in summer.
The utility poles move closer together when it is hot.
The air pressure is lower in summer, allowing the cables to hang lower.
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.