Applications of expansion and contraction


•    Water has a unique property. It contracts on cooling until it reaches the temperature of 4°C.

•    However, when it is cooled further from 4°C to 0°C, it expands. So, ice floats on water.


The jammed metal lid:

•    The jammed metal lid of a jar can be opened by heating.

•    The jar is inverted and just the lid is dipped in hot water. After some time, the lid can be opened easily as the lid gets slightly expanded.


Rubber tyres:

•    The rubber tyres used are slightly smaller in diameter than the wheels.

•    The tyres are heated so that they expand. When they become slightly bigger, they can be easily slipped onto the wheels.

•    When the tyres cool, they contract back to their original size. They press tightly onto the wheels and cannot come off.

•    In this way, mechanics fix tyres around the wheels of cars.