Physics
Pipelines in cold countries often burst in winter, because

Pipelines expand due to freezing
Pipelines contract in their volume
Water freezes and expands in its volume
Temperature of ice is less than that of water

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Physics
Light houses are places with powerful lights to :

Guide and help large crowds at religious gathering during nights
Indicate to the incoming warships, the location of a harbour during night
Guide and warn the ships coming from different directions in the ocean
Guide and resolve traffic jams in crowded metro-cities during nights

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