Question

expansion amd contraction​

Answer 1

Answer:

Substances expand (increase in size) when they get warmer, and they contract (decrease in size) when they get cooler. This property can be useful.

For example:

Thermometers work because the liquid inside them expands and rises up the tube when it gets hotter.

Metal parts can be fitted together without welding, using shrink fitting. The slideshow shows how this works: