While on a trip to Iran, he came across a body of quicksand near a lake. One particular example was conducted by Daniel Bonn from the University of Amsterdam. Interestingly, some scientific experiments have been conducted in the past to attempt to simulate and study quicksand under more controlled conditions and without risking anyone's life. It is thought, though nobody really knows why, that this is where quicksand gets its public reputation for being incredibly dangerous. However, it is theoretically possible to be killed by quicksand if you lose your balance and fall in such a way as to drown. On top of this, quicksand pits are rarely more than a few feet deep, allowing most adults to touch bottom while still only waist deep. However, even with these denser materials, the human body has a density close to, but still less than water at around 8.3 lbs/gallon (1,010 kg/m3).įor this reason, if you were unfortunate enough to accidentally step into quicksand, you should only sink up to about your waist if no effort were made to escape. While the human body is primarily made of water (about 60%), it has other denser materials within it, like muscle, that can increase the average density of the human body. In other words, 1 kilogram of water takes up 1 liter of space. Water's density, for example, is 62.4 lbs/ft3 (1 kg/L). The density of sand and water that make up a body of quicksand exceeds that of a human body, and so, you cannot easily completely sink within it. This is because quicksand, while a hazard, cannot defy other basic laws of physics - namely buoyancy. Quicksand can also be found where sand, mud, and vegetation mix together in bogs.Ĭontrary to popular belief, however, you can never actually completely become submerged in quicksand. Instead of weakening and thinning, like quicksand, these materials react to a sudden addition of stress of force by rapidly stiffening, providing a form of a shock absorber.Ĭertain places are prone to quicksand formation like, for example, hollows at the mouths of large rivers, along flat stretches of stream, beaches where pools become partially filled up with sand, and where an underlying layer of stiff clay or other dense material prevents drainage. Such materials are ideal for impact protection for things like bullet-proof vests and motorbike armor. There are other materials that have the exact opposite properties of " shear-thinning thixotropic non-Newtonian fluids", appropriately called "shear-thickening thixotropic non-Newtonian fluids." One example is cornstarch in water (also known as oobleck). If, however, you do struggle, you will continue to disrupt the system, worsening your problem fairly quickly. If you take our advice and stay calm, eventually the equilibrium of the quicksand will be restored, preventing you from sinking further. This is primarily because the frictional forces between sand grains that would normally be able to resist your weight are temporarily lubricated. This leaves a layer of densely packed wet sand that cannot support your weight and causes you to sink. This causes the body of sand to liquefy resulting in the water and particulate matter separating. This sudden "shock" disrupts the careful balance of sand and/or clay or mud and water. This is exactly what can happen when an unfortunate individual accidentally stumbles upon some quicksand and steps into it. This is called its "yield stress", which, in the case of quicksand, is fairly low, at around a 1 percent increase in the weight on top of the quicksand.
Just like quicksand, they may appear solid initially but are able to flow when an increase in pressure or force is applied to them - like squeezing a toothpaste tube for example.įor this to happen, enough stress or force must be applied to enable the substance to flow like a liquid.
Toothpaste, some syrups, and hair gels are all other examples of them you'll meet every single day. Interestingly, there are plenty of examples of similar non-Newtonian fluids in your home too. Scientifically classified as " shear-thinning thixotropic non-Newtonian fluid", colloids like quicksand do not follow the normal laws of physics associated with liquids and/or solids. It tends to form when saturated loose sand is suddenly agitated and the suspension water cannot readily escape. A colloid is a special kind of mixture of microscopically dispersed insoluble particles (clay, sand, silt for example) suspended in another substance, like water.
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