How many times have it happened to us walk with a hand cup of tea or coffee and see that suddenly small ones are formed wave On the surface? Waves who, sometimes, force us to walk extremely slowly to avoid overturning the drink on the floor. But is there a scientific method to minimize this annoying effect? This is the question that physics has asked Jiwon Han from the Korean Minjok Leadership Academy and winner of a IG-NOBEL Award in 2017.
The first thing to consider is that the fact of overturning of the coffee (or tea) on a cup it depends only in part on how much we have filled it. If we put the same amount of liquid in one cup and in a chalicewe will see how walking at different speeds the two liquids behave differently.
The oscillation is therefore mainly caused by way we keep the cup. When we walk, in fact, we get rid of oscillate the coffee in the cup And over time our movement can even resonate with that of the drink, amplifying it.
To decrease this effect it has been noted that a first option is walk back: In doing so the movement of our hand is more regular and gives less shocks to the cup. Obviously also the author of the study understood that this is one bad idea Because the chances of falling, stumbling or hitting someone while walking backwards are much higher than not to pour the coffee by walking normally. An alternative method was therefore proposed: the hook hold.
If you grab the cup as in the image above – without burning – The resonance effect is reduced and the chances of pouring coffee are lower! In addition to this, it was also observed that the presence of foam on the cappuccino reduces resonance, as well as having cups with onetighter opening.
