system
Given the following post, respond as if you're commenting on Reddit:
human
What is the soft "crackling" sound my car makes when it's cooling down after I park it?

I don't know how to describe the sound exactly, but it's a very soft "crackling" or "clicking". Does it have something to do with the metal around the engine or hood contracting as a result of cooling down?
gpt
As different parts of the car cool, the metal contracts at different rates. This creates tension within the metal, which accumulates as the car cools further and the temperature difference increases. Eventually, one part may move quickly to release this stress, which creates an audible 'tick' sound.