Honey drips due to a combination of gravity and a phenomenon called the Rayleigh-Plateau instability.
Here's a breakdown of the process:
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Gravity's Role: Gravity pulls the honey downwards, initiating the drip. As honey flows from a spoon or container, it forms a thin stream or jet.
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Rayleigh-Plateau Instability: As the stream of honey descends, its weight causes it to stretch. This stretching makes the stream thinner and more susceptible to the Rayleigh-Plateau instability. This instability refers to the tendency of a cylindrical jet of fluid (like honey) to break up into smaller droplets to minimize its surface area. Imagine tiny fluctuations in the diameter of the honey stream. These fluctuations grow over time because a smaller diameter has higher surface tension causing the higher surface tension area to pull liquid from the area of larger diameter.
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Viscosity's Limited Influence: Surprisingly, according to the reference, the dripping and stretching process is primarily gravitationally driven. While honey's viscosity (its thickness and resistance to flow) influences the speed at which it flows and stretches, it doesn't negate the fundamental effect of gravity and the Rayleigh-Plateau instability causing it to break into droplets. Essentially the viscosity of the liquid causes the dripping to be slow and controllable, but is not the driver of the drip itself.
In simpler terms, gravity starts the drip, the honey stream stretches, and instability causes it to pinch off and form individual droplets.
