Physics Shows Us The Best Way To Cool Down Our Coffee

Photographed by Alexandra Gavillet.
Back in high school, I was horrible at physics. To this day, I still don't understand the Doppler Effect, how to calculate velocity, or what exactly causes black holes to form. After almost 10 years, though, I have finally found some physics that I actually do care about, and that's because it holds the secret to cooling my morning coffee.

A science writer for Wired named Rhett Allain recently performed an experiment to try and figure out the most efficient way to cool a cup of coffee, and the results may save us from ever burning our tongues again. The investigation started with three cups of coffee. One was cooled down by blowing into the small hole in the coffee cup's lid, one was cooled by removing the lid altogether, and one (the control cup) was left untouched, with its lip on. Allain gave each cup its own thermometer to keep track of cooling rates. The very scientific study revealed that — drumroll, please — the lid removal methods is the best and most efficient way to cool down your coffee.

In his article, Allain says that physics is what's behind this method's cooling success. Specifically, we have to thank a little something called "cooling by evaporation." If you think back to what you learned in those basic science classes, you might remember this term. Allain explains, "As water on the surface of the coffee evaporates, it leaves behind lower energy water molecules, resulting in a lower coffee temperature." When you remove the coffee cup's lid, there's a greater area for the water on the surface to evaporate. So, it cools down more quickly.

Based on the grade I receive in that 9th-grade physics class, I'd never have thought I would one day be thanking physics, but there's no denying, in this situation, the subject really comes in handy.

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