Physics

I know there is venous pooling due to gravity but how does this exactly affect pressure exerted on the walls of blood vessels. Does diastolic or sytolic blood pressure decrease? Thanks!!

http://www.backgroundscity.net/data/detailthum/4/clouds%20In%20Jamaica.jpg Look carefully. Why is there a "shadow" of this cloud visible?

Why may one not have a complete vacuum? How does every single particle both function as a particle and a wave? How does quantum tunneling work? ~Cyf

Hello everyone, Quick question. When there is a pipe and you constrict it there is higher pressure loss. Is this pressure lost permanent? What is this pressure loss, is it loss as heat, are liquid molecules converted to heat, are they lost? What happens to liquid molecules if the hydrostatic pressure drops to zero do they stop or do they still move because of the kinetic energy? Thanks!!

I recently graduated high school and it only made me realize how much I fudged it up. I slept every day in math class and I never took physics or chemistry. The thing is that I know I'm a smart person and I have an incredible yearning to learn everything about the fundamentals of the world we live in. I just want to expand my knowledge more than anything. The only thing I lack is the resources. I can't make it to college, not at the moment anyway. I was just wondering if anyone could direct me to a website where I could teach myself the basics of physics and the math I need to understand physics. I just need something temporary to teach myself until I can get back in scho…

How did space come into existance?

Hi: What is the minimum intensity laser possible? 1-photon-per-second is too small an intensity. Thanks, Green Xenon

I am looking to start a business up which will be producing sea salt. I am looking at ways to reduce the energy costs and would like to explore vacuum evaporation of sea water. My question is how much energy would this require if had to evaporate 75% of the water in a vacuum to obtain the salt. Assuming I am starting with one litre of water.

how many watts is deadly to a human?

Are the space trash really dangerous for an ordinary man that is living on the planet earth or no? if so, what is its danger? i know they're dangerous in some ways; but i want t know 'bout their influence on ordinary people.

if one had two glass bottles filled in with, say aluminium, with a metal rod sticking out of the top, and connected the metal rods to a battery, would the bottles build up charge/ become charged?

Hi: Is it possible to generate coherent light with a device other than a laser? If so, has this ever been done before? Thanks, Green Xenon

I was just thinking,which I try not to do, But it occured to me that everything since the dawn of our planet is still here, What I mean is that all living things and non living things never left our planet into space. This means that all mater is still here but in a differant. Kinda like a recycleing proccess..

Hi: Is it possible to design and build a laser that emits 400 nm light at the extremely low intensity of 1-photon-per-second. This is one extremely low power laser! Thanks, Green Xenon

First of all I have to say I have really confused myself on this one by overthinking and I'll ask my questions step by step. Any help would be greatly appreciated. General rule is when blood vessels constrict blood pressure increases. 1. Ok there is a container and gas molecules in it. If I decrease the volume of the container the pressure increases. This analogy can not be used for blood vessels right? I mean it is a liquid and has a blood flow. 2. It is said that when blood vessels constrict blood pressure increases. Blood pressure means the pressure at which the heart pumps the blood right? So when they say an increase do they mean an increase in blood pressu…

am i right in thinking that transformers can step up voltage to much higher levels? if so then what is the point in voltage multipliers? they are pretty complicated in comparison so surely it is alot simpler to use transformers?

Someone recommended I view lectures by Fibel or Sasel, at least that's how he pronounced the names. Say it out loud and if you can recognise it, please tell me the correct names (I tried googling either) So Fibel or Sasel/Cecil. Please if you have the time, Cyf

A-----------------------------B If static pressure in A is higher how does it create a flow from point A to B. If static pressure is acting perpendicular to the dotted line how can it push molecules in the horizontal direction, which is the direction of flow? Why do you need a pressure difference to drive a flow. Can't supplying liquid with a high pressure pump to a pipe cause flow?

In the journal physical review B, there is a section devoted to "Inhomogenous, disordered and partially ordered systems". Could someone please explain to me what each of them means?

Let's say you have a container and it is in high pressure? If the pressure is force exerted on the walls of the container. Each time particles hit the wall won't they encounter resistance? So doesn't high pressure, mean more resistance and results in low pressure overall. I mean with more force you hit the walls, higher the resistance force so at the end it is low pressure. Is the reason that this doesn't happen is because normally resistance is not high enough? Also what do they mean by hydrostatic pressure loss? I understand what is hydrostatic pressure. If it is lost due to friction, what do they mean do the particles turn into heat or just stay there with no energ…

Ok after hours of contemplating I think I finally understood the concept(hopefully ). However I still need 1 quick clarification. When water flows suddenly from a larger to a small dimater Bernoulli says 1. Pressure decreases 2. Velocity of fluid increases I'll put numbers just for easy understanding This is according to Bernoulli assuming no loss Energy in large diameter (Hydrostatic pressure=4 Kinetic energy=2) Energy in small diameter(Hydrostatic pressure=2 Kinetic energy=4) Ok in real life when you consider resistance in the smaller tube is it the K.E that is lost to create lower fluid velocity. If hydrostatic pressure is the pressur…

Hi all, I was wondering why is it that some coins need to be rubbed in order to be accepted by vending machines. Is it making the edge more conductive by removing some grease and thus allowing for a resistivity measurement inside the machine ? Any bright ideas, references ? Thanks in advance, McCrunchy

I'm so confused with bernoulli principle. Let's say there is a pipe and a constriction in the middle third. 1. When fluid moves from greater cross sectional area to less (constriction) how does pressure decrease. I mean more molecules are hitting the walls inside the constricted area shouldn't this increase pressure? 2. Why does velocity of fluid increase? I mean when something is constricted isn't it hard to fluid to go through it, meaning output is less volume. 3. When a blood vessel is constriced there is higher blood pressure? How does Bernoulli explain that. Thanks

Hey everyone! I am struggling with an assignment for an Bioelectricity subject....if anyone has a bit of knowledge on GHK and cable theory, please contact me...I would really really appreciate your help! Thanks! Aimee

If a blood vessel consticts, the resistance increases and kinetic energy decreases, if kinetic energy decreases hyrdrostatic pressure must go up but why does other occur? "The average capillary hydrostatic pressure is determined by arterial and venous pressures (PA and PV), and by the ratio of post-to-precapillary resistances (RV/RA). An increase in either arterial or venous pressure will increase capillary pressure; however, a given change in PA is only about one-fifth as effective in changing PC as the same absolute change in PV. Because venous resistance is relatively low, changes in PV are readily transmitted back to the capillary, and conversely, because arterial…