Telephone lines made of copper wire are installed between poles on a hot summer day. The engineer leaves some slack in the wires, allowing them to sag slightly.
Why are the wires not pulled tightly to make them completely straight?
They will contract on cold winter days.
They will contract on hot summer days.
They will expand on cold winter days.
They will expand on hot summer days.
96 exam-style questions on CIE IGCSE Physics 2.2.1 Thermal expansion of solids, liquids and gases. Each one has a worked solution and a mark scheme showing where the marks go.