For example, I noticed that when I pour a soda on the side of a glass instead of directly into the cup, it forms less bubbles. This is also evident with rootbeer floats. Is this an actual scientific phenomenon or am I just imagining things?


It's absolutely true. The bubbles are formed because of the speed with which the stream of liquid hits the surface. When you pour along the side, you take advantage of two things:

  • first, the liquid slows down (because of viscous drag against the wall)
  • second, by giving the liquid a solid surface, you prevent the formation of Rayleigh instability which tends to break a liquid stream into drops.

The bubbles are formed because of the violent distortion of the surface when you hit the water quickly, or with a rapidly changing force. Both the above effects reduce this - and no, you are not imagining things.

The above mentioned link contains a subsection that has a particularly practical example of how the above physics affects men every day...


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