Facts

Published May 21, 2022

How dangerous is quicksand

Quicksand is a mixture of water and sand or silt. It has the characteristic of thixotropy: it looks solid, but when pressure is applied it liquefies (acts like a liquid). If animals or people stand on it, they sink into it. However, a human or animal does not sink entirely into quicksand due to the higher density of the fluid. It can be difficult to get out: that is the real problem.

Difficult to Get Out Of

Why is it so difficult to escape? The reason, according to a study, is that, after its initial liquefaction, quicksand’s apparent viscosity (thickness or flow resistance) increases. The increase is due to the formation of sand sediment, which has a very high viscosity. It’s the difficulty of moving this dense sand that causes the problem.

Therefore, water has to be introduced into the sand sediment to loosen it, and this requires considerable amounts of force. The study estimates that the force needed for someone to pull their foot out of quicksand at a speed of a centimetre a second would be the equivalent of that required to lift a medium-size car.

Published in Dawn, Young World, May 21st, 2022

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