Beer easier to carry than coffee
Seemingly-obvious discovery as French scientists slosh beverages around
FRENCH and American researchers have made a scientific breakthrough in discovering why beer is easier to carry without sloshing than coffee.
It may seem obvious, but they have proved that the difference is in the foam.
The discovery is not just a question of how stable coffee cups are compared to beer glasses as the boffins compared like with like - showing that if you walk with a beer glass filled with fresh-brewed coffee and then suddenly stop, it sloshes more violently and for longer compared with the same glass filled with beer.
They examined the effects – called damped harmonic oscillation – with a set-up including a mechanical vibrator and a high-speed camera.
It turned out the foam on the beer was the vital element: the more foam, the more damping – so 1cm of foam damps more than 0.3cm (a single line layer of bubbles) and 3cm of foam damps more still.
The bubbles (preferably five layers thick or more) stick to the glass walls forming a shield which disperses and absorbs energy from the liquid rubbing against it.
They concluded that “foam damps sloshing through viscous dissipation on the container walls” – which, translated, proves that “beer is easier to carry than coffee”. The same is true for latte, as it is easier to carry than ordinary black coffee.
While this might seem like useless information, the scientists, from the CNRS and Princeton, think their research, published in Physics of Fluids, may be of use in transport of liquids by tankers or as cargo – so it is not as silly as it sounds.
For the complete scientific explanation see: Fluid Motion.
