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Why does runny honey stop dripping when there is still plenty left on the spoon?
David Muir
Edinburgh, UK
There are two competing forces at play here: viscosity and gravity.
Gravity is pulling the molecules in the honey downwards and causing them to separate and start flowing. On the other hand, intermolecular forces between the particles within the honey resist the flowing motion, and the viscosity of the honey is directly proportional to their strength.
The honey stops dripping when the intermolecular forces between its molecules overcome gravity. The intermolecular forces in petrol (gasoline), for example, are much weaker, so…
