Have you ever wondered how much? physics hiding inside a cup coffee? What can one discover while preparing his morning refreshing drink?
These are two questions that can be answered through the explanation of an equal number of “experiments”, which are not only related to our everyday experience but also to physics.
For the first one experiment, take a mug and pour in a spoonful of instant coffee (or more if you’re sleepy..). Then fill it with hot water and mix with a spoon. Pick up the mug and with the same spoon start tapping the base of the mug, you will notice that as you tap the sound that is heard becomes more and more sharp. The volume will continue to increase as you tap for about a minute. After a while mix again. When you start to “rattle” the bottom of the mug with your spoon again, you will realize that the volume of the sound starts to decrease!
The “melody” pouring out of your coffee mug is due to the hot chocolate effect (Hot chocolate effect). Its name comes from a research publication by the physicist Frank Crawford (Frank Crawford), who was working at the Lawrence Berkeley National Laboratory in the USA and noticed the phenomenon while drinking his hot chocolate with a friend.
The cause of this phenomenon is the bubbles (trapped air) that are created inside the drink after mixing. Essentially, when I hit the mug with the spoon, I create a sound wave, a disturbance, which starts at the bottom of the mug and travels at a certain speed through the molecules of my coffee. These molecules in the presence of the sound wave begin to oscillate back and forth, creating concentrations and dilutions in the medium (ie, my coffee). The sound that reaches my ear is spread through these thickenings. The square of the speed at which the sound wave propagates is inversely proportional to the density of the medium, so bubbles which are areas of high density within the coffee have the effect of reducing the speed of propagation. But because the speed of propagation is linked to the frequency carried by the wave (the two quantities are proportional), a reduction in speed brings about a reduction in frequency, so a heavier, reduced sound. But when the bubbles gather on the surface of the coffee cup, then less and less of the solution contains points of high density (i.e. lower sound speed), so the sound intensity increases approaching the value it would have for a liquid without bubbles.
For the second experiment, let’s take a cup of coffee again. We notice the black, vast, color of coffee covering the inside of the mug. Now pour some milk into the coffee. You will notice that the black color of the coffee starts to acquire white highlights due to the milk. If you leave the coffee mug alone for a while, without stirring, you will notice that the coffee mixture has acquired a uniform brown color.
As a consequence of this redistribution of the black and brown areas in my drink, is the second law of thermodynamics, which explains to us that for a closed, isolated system (cup of coffee with milk), its entropy (the measure of the disorder of the milk molecules inside in coffee) constantly increases, leading to mixing of the molecules inside the drink. The end result is a drink of high entropy, i.e. a situation where it is difficult (I would say impossible) to separate the coffee molecules from the milk molecules. In other words, we have reached what I call in the world the natural, irreversible state.
From the above “experiments” it becomes clear that the everyday life that surrounds us can be explained simply through physics. The music of a cup of coffee or the entropy in its system is simply the beginning before the great road of our unexplored world.
#Natural.. #drink #mug
