there is even a creature, a small spider, than runs extremely fast, with very powerful legs and a very light body, that can run accross water because of the resistance to deform.
Did you refer to water strider? If so, that's an insect, not a spider.
]]>I heard that if you lie on your back in quicksand you cant sink. Is that really the case??
This says that 'If you are sinking beyond your thighs, lie back and distribute your weight evenly over the surface. Don't lean forward or try to crawl or "swim" out unless you are in really deep! In thicker mud and quicksand, this will only work you in further. Lying back causes you to "backfloat" so that you can slowly and carefully pull your legs free. Once the legs are out, roll over the top and onto firm ground.'
So, I think lying on your back doesn't make you unsinkable, but it might help get you out of sticky situations.
]]>That spider doesn't use viscosity to do that though. If that was the case then it would sink when it stopped, but it can be stationary on the water and still float. Instead, it relies on the fact that its weight isn't enough to break the surface tension.
There are other creatures that can run across water in that way though. Some lizards can, for example.
ah well , i thought that was the case, not that it wouldnt be possible though.
]]>There are other creatures that can run across water in that way though. Some lizards can, for example.
]]>glass is an example of a fluid with an extremely high viscosity, (yes glass is NOT a solid, but a fluid)
quicksand, custard are examples of fluids with an obvious extreme less viscosity, but high enough to give resistance.
its like friction, as the force against the fluid increases, the frictional force increases exponentialy, so apply a small force to the fluid, and you get very little resistance, but apply a large force, and you get an extremely high resistance, the reason why standing still, you would sink, but if you try to move quickly to get out, it feels like a solid, and stops you moving, similarly when walking/running on the custard in braniac, you apply a large force to the fluid, and it gives a large resistance back, enough to let you walk on it
there is even a creature, a small spider, than runs extremely fast, with very powerful legs and a very light body, that can run accross water because of the resistance to deform.
]]>If you're curious as to why scuba divers are able to withstand the pressures of the deep, it's because they are breathing from a pressurized tank. The regulator (mouthpiece) matches the pressure of the air they breathe to the pressure of the water outside (the "atmosphere"), so the balance is maintained and the diaphragm doesn't have to do any extra work. Breathing with a SCUBA feels just like breathing at the surface.
A standard scuba tank holds 3000psi of air. That pressure isn't matched until you get to a depth of about 7125 ft. Of course, at that depth you'd use up your whole 3000psi tank in 3 or 4 breaths. You'd also have a lot of other issues to deal with...
Sorry to go OT; I just love scuba diving.
]]>Haven't you ever been buried in wet sand at the beach?
Yes.
I thought it was a big mound of dry sand I was jumping into, but actually, it was a large pile of wet muddy sand. You can imagine what happened.
And then there was the time I was wearing thongs on the beach and they got suctioned into the sand ...
]]>A sand-water mix would probably be quite restrictive on the movement of your lungs.
Your rib cage does expand when you breath. Pressure upon it makes it so that you can't expand your chest. If you are floating chest up, then your chest is very near or above the top of the quicksand. This means that there is very little weight, and thus, very little pressure upon your chest.
Haven't you ever been buried in wet sand at the beach?
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