Application of thermal expansion:

1. In thermometers, thermal expansion is used in temperature measurements.
2. To open the cap of a bottle that is tight enough, immerse it in hot water for a minute or so. The metal cap expands and becomes loose. It would now be easy to turn it to open.
3. To join steel plates tightly together, red hot rivets are forced through holes in the plates. The end of the hot rivet is then hammered. On cooling, the rivets contract and brings the plates tightly gripped.
4.  Iron rims are fixed on wooden wheels of carts. Iron rims are heated. The thermal expansion allows them to slip over the wooden wheel. Water is poured on it to cool. The rim contracts and becomes tight over the wheel.