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How do ice cubes cool a drink? – Helen, age 12, Boston, Massachusetts

How do ice cubes cool a drink? – Helen, age 12, Boston, Massachusetts

I like to make my own iced tea. First, I steep about a quart of terrifically strong hot tea and pour it into a pitcher loosely filled with ice cubes straight from the freezer. The result is about two quarts of delicious, cold tea, with a few ice cubes floating on top.

What’s the science behind my perfect pitcher of iced tea? A simple answer is that the near-boiling tea transferred its hotness to the below-freezing ice cubes. This transfer raised the temperature of the ice cubes so that much of the ice melted. That both cooled the tea to a refreshing drinking temperature and diluted it for a proper taste.

My iced tea process reminds me of physics experiments I worked on that flew on the space shuttle Columbia in the 1990s. I was interested in how liquids turn into solids in the absence of gravity.

Both those space experiments and the making of iced tea depend on liquids or solids getting hotter or colder in just the right combination. The explanation for how it all works depends on two related concepts: temperature and energy.

What are temperature and energy?

The concept of temperature grew out of the sense of what feels hot and cold to human touch. Boiling water is too hot to touch safely, and a candle flame is even hotter. Ice cubes feel cold. A thermometer is a special hotness meter that more reliably and........

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