[Closed] The I LOVE SCIENCE Thread

Can the airplane/conveyor people get their own thread? Or, better, do some Googling, reading and thinking?

Or you could just explain it to us

thats what ive been trying to do.

my question was related to the statment you made that water is non-newtonian in nature

I thought water was one of the few Newtonian (or near as damnit) fluids

thats what ive been trying to do

I know, and you've done very well, it's just that there are still some big gaps in my understanding. But given that mike asked us to go our own way and I guess he's the thread owner or boss or something, we'll have to leave it for now

The first 1.5 pages of this thread were great.

i didnt intend to ruin it. its just been a very slow day.

Or you could just explain it to us

It takes off, because of science.

I know what a non newtonian fluid is, although it has been a long time since I studied them at Uni, my question was related to the statment you made that water is non-newtonian in nature as there is nothing that I can find that indicates any sort of time or shear rate viscosity variation.

Pump the water through a pipe, add a heat source to the pipe, does the viscosity of the water change along the pipe? Yes, therefore it's non-Newtonian as you've introduced a time dependance to the viscosity .

You make an assumption that a fluid is newtonian to make the maths simple, pretty much all liquids are going to thin with a change in temperature. In reality it will be non-newtonian to a degree. Just like the ideal gas law is applicable to most cases even though we know it doesn't model the behavior of real gasses.

Pump the water through a pipe, add a heat source to the pipe, does the viscosity of the water change along the pipe? Yes, therefore it's non-Newtonian as you've introduced a time dependance to the viscosity .

Err, no. You haven't introduced a time dependancy you've introduced a temperature dependancy. Variation in viscosity due to temperature is nothing to do with whether or not a fluid is Newtonian or not. A time dependant non newtonian fluid will change viscosity after a period of time at constant temperature.

Err, no. You haven't introduced a time dependancy you've introduced a temperature dependancy. Variation in viscosity due to temperature is nothing to do with whether or not a fluid is Newtonian or not. A time dependant non newtonian fluid will change viscosity after a period of time at constant temperature.

du/dt is non newtonian then surely you can see that if du/dT is applicable to most fluids, and a heat source gives dT/dt then du/dT * dT/dt = du/dt (where u is 'mu' for viscosity). The water is less viscous after some period of time.

the shape of an aircraft wing is such that the air passing over the top of it has to travel further than the air passing under it. to do this is has to travel faster. this creates low pressure above the wing and that in turn creates lift. how much air is needed and at what speed is dependant on the shape, size and orientation of the wing.

I thought the Bernoulli effect had been proven to be a minor contributor to the lift generated by an aircraft wing and everyone was now taught it was newtons 2nd law.

It takes off, because of science.

Good science or bad science?

[IMG] [/IMG]

And more to the point - if plane takes off and someone switches the conveyor belt off - and so the plane crashes - where do they bury the survivors?

in a non nutonian fluid.
and spoon, i had not heard that. interesting.

Seeing as all of science is based on maths....

e^i? = ?1

......end of thread

du/dT * dT/dt = du/dt

but t has no effect on u, only on T. If you hold t constant, all the variation in u is due to T.

this might be a correlation causation conflation confusion

Sorry TINAS, but just because something is temperature dependant over time, and hence density/viscousity dependant over time, doesn't make it [b]primarily[/b] non neutonian, imo of course 🙂

The water is less viscous after some period of time.

Only as a result of the heat, not due to the passage of time. For it to be a time dependant non newtonian fluid the viscosity would have to change over time at constant temperature.

the shape of an aircraft wing is such that the air passing over the top of it has to travel further than the air passing under it.

IIRC, this is "GCSE science" and somewhere between a gross simplification and wholly wrong. I'll try and dig something up after I've done cooking.

Cougar is correct - the "goes faster because it has further to travel" notion is wrong. Why should the flow over the top of the wing have to arrive at the same time as the flow under the wing?

In fact, the shape of the wing causes the airflow to compress and this is why it moves faster - and why the pressure drops (Bernoulli's theory). This is still a bit of a simplification, but a better one!

Why should the flow over the top of the wing have to arrive at the same time as the flow under the wing?

Well because the faster flow underneath would create an area of lower pressure at the back of the wing to suck it over. Stevomcd's explanation boils down to the same thing.

Well if the air over the top didn't go faster then more air woulbe passing under the wing and as air is not compressible at subsonic speeds, conservation volume results in the air going faster over the top.

The sirflow does not compress, steve.

Well if the air over the top didn't go faster then more air woulbe passing under the wing and as air is not compressible at subsonic speeds,

Umm air is most certainly compressible at "subsonic speeds". All gases are.

Ok, but in terms of flight dynamics, in free air for mathematical models it is in effect incompressible.
Further it only becomes about 5% compressible at M0.5 and the Bernoulli model for flight applies at much lower speeds

Edit.

this therory works upon the princables that toast always lands butter side down and that cats always land on their feet. what you do is strap 4 peices of toast butterside up to the cats feet this means that the toast cannot land on its butter side and the cat cannot land on its back so you get levitation now wrap the cat in a thin layer of copper wire and place between two magnets and you have an unlimited frictionless supply of energy.

ill get my coat

Toast does land butter side up if you carry it butter side down. I can't believe this is not widely known.

I could come up with some equations given a bit of time. I might do this tonight for a laugh.

Toast does land butter side up if you carry it butter side down. I can't believe this is not widely known.

It's related to the height from which it's dropped. Which is usually worktop height. Which is based on the human form. The human form is limited by the physical properties of bone. This is caused by atomic structures and bonding. These depend upon the weak and strong nuclear forces, which were set during the Big Bang.

So, [b]the fact that toast always lands butter side down was built into the very fabric of the universe at the dawn of time[/b].

It's been a good week for science.

We might have cured AIDS.

http://www.abc.net.au/news/2013-01-16/scientists-hail-potential-cure-for-aids/4466766

We might have cured Alzheimer's.

http://www.sciencedaily.com/releases/2013/01/130115143852.htm

And in our spare time we're still exploring.

Hmmm that cure for AIDS isn't a cure for HIV. Don't get me wrong if it pans out then it's fantastic news but the headline is misleading.