1 telephone cables sag during summer

2 railway tracks are provided with expansion slots

3 a tight bottle lid can be loosened by running hot water on the lid etc.

when you heat something up it expands. if you could measure a pot of water as you heat it ,it would get a little fuller

another example.

some engines have cylinder sleeves. you cant put them in the engine because the size is to close.

so you put the sleeves a freezer to shrink them.

you cant see that they shrunk but with a micrometer you can measure it .after you put them in the engine they warm up and expand so they fit tight.

a simple test to show you. fill a glass jar with water

and put the lid on tight. now put the jar in a plastic bag. place the bag in the freezer after the water freezes ith jar should break. that’s from the water expanding.

water is the only thing that expands when it gets colder. everything else shrinks