Physics

Is there any study or research on approximately how much damaging or harmful UV could reach inside a room in an apartment building of a city without any UV film or curtain? It's said most harmful UV is already blocked / absorbed by the glass of windows or other obstacles before reaching inside. Is it validated?

Evening. I am having a problem with a new engineered timber front door which has a man made core and oak veneer surface. The door is painted in three coats with quality paint and has a dark grey finish. The door faces east and is well protected from the rain. Over the past few weeks on sunny afternoons, the door warps approximately 6mm and then returns to its straight shape sometime the next day. The door supplier says this is because the paint system isn't stopping the UV radiation and are refusing to do anything. Surely no paint can stop the warming effect of the sun and as the paint is dark grey presumably it is actually increasing the …

does UV radiation have the ability to break up water molecules? if so please specify the wavelength

Earlier this week i went on a school tour and i was sitting in direct sunlight for 3 hours on the school bus yet i wasnt sunburnt at all ?? I was wondering if UV radiation can pass through glass ??? If not then why?? Does it pass through water(i have been burnt wile swimming)?? Does infra red radiation pass through water or does it just get absorbed ?? P.S I live in south africa 3 hours of light is more than enough to get seriously burnt even now during winter!!! P.P.S thnx in advance

I'm reading The Night's Dawn Trilogy and Haimlton mentions this pretty often. The rest of the story is full of proper scientific concepts, but the only references I found about vacuum ablation say it's nonsense. Certainly, the idea that materials would "boil away" in empty space doesn't sound very convincing. Is vacuum ablation real? At what pace would a spaceshuttle hull ablate? And what is it that really causes the ablation? Radiation? The cosmic microwave background?

Hi. Lost in space on how to calculate, or how to make a nomogram/chart; please some guidance. 1 litre of water at 20C in a regulable vacuum chamber, no heat added. At what amount of vacuum will the litre evaporate in one hour ? Or, if wanted to evaporate 1 litre in one hour, how much vacuum should be applied ? ============== Now, the water can freeze if the vacuum is considerable ( I do not know the figure), so that should be avoided if evaporation is desired, as if frozen, the 'sublimation/evaporation' speed would considerably decrease -Am I wrong there ? The optimal condition could then be to keep the boiling water from freezing (about not less than 5C…

Are there any experiments constructed for detecting vacuum energy ? What role the vacuum energy have ? and how it interacts with matter ?

Sorry, I was unsure which subcategory this should go under. I was having a sci-fi discussion recently and talking about means of intersellar propulsion available to possible advanced cultures. Would it be possible to somehow tap vacuum energy to create a force to propel a spacecraft? What would you need to harness it? Could you, for instance, have positive energy created infront of the spacecraft, pulling it forward, and negative energy created behind, making the spacecraft/space expand away from it?

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.

I've been thinking, we have so many means of power, but all of which begin with the use of a potential/normal energy. However I believe that a chain of energy can be started with a force, a force such as a vacuum. (I don't think as gravity as a force that could start an energy chain because gravitational potential energy is basically gravity.) Nothing is all around our little blue planet right? So doesn't that mean we should utilize it? We could create something that would transform kinetic energy into a usable electrical potential energy. I was thinking a wheel or something that had a constant flow of air fed to it through a tube, and after which is rushed out of the tub…

Newb here... didn't know where else to post this.... I realize there are rigid solids that will hold a vacuum for a very long time, but is there any flexible plastic or fabric that will hold a medium vacuum for a very long time? Another way of asking this... is there a plastic -- or even a coating that can be applied to a plastic-- which will not allow any molecules found in the atmosphere through? An actual zero-permeable material? How long will the bags used in vacuum food storage hold their vacuum?

Can anybody explain to me why holes are found at the top of the valence band, whereas electrons are found at the bottom of the conduction band.

I searched the internet for the last 2 hours learning and understanding the Watt/Watt Hour/BTU conversions using data collected. I am not sure what I might be missing, but Wikipedia has supported that a defined Watt ~ 3.412 BTUs. Some simple constants: 1 Watt (W) = 1 Joule per second 1 BTU Hour (BTU/h) ~ 1055.05585 J 1 hour (h) = 3600 seconds (s) So, inherently, a simple formula can be derived to convert BTUs into what I believe should be Watts: W = Joules(BTUs)/Time Elapsed(seconds) OR 1055.05585/3600 ~ .293 W Rating Their number of 3.412 has apparently been used by applying: W = 1 Hour (Seconds)/Joules OR 3600/1055.05585 ~ 3.412 W Thi…

Is a 1 Newton of gold worth more on the Moon than on Earth?

correct me if i'm wrong but i am under the impression that, put simply, in a van de graaf generator the belt gains electrons from the positive terminal and then the large dome gains electrons from the belt. if it has all these electrons (which have a negative charge), does this not mean that it would gain a negative charge? I'm just confused because on all the diagrams i have seen they put positive signs (+) around the large dome.

The Van der Waals equation of state for gases: [math]\left(p + \frac{n^2 a}{V^2}\right)\left(V-nb\right) = nRT[/math] where "a-prime" is the attractive force between gas particles. My question is, does "a-prime" already account for any paramagnetic interaction that may arise in gases with un-paried electrons like triplet [ce] O_2[/ce]? Or, does "a-prime" only factor in the Van der Waals (induced dipole-induced dipole) interactions present meaning that one would have to account for paramagnetic interactions separately? I realize one could neglect the paramagnetic interactions entirely for most purposes, obviously they shouldn't add up to much in the gas…

Is anyone familiar with van der waals forces in plasma, and or maybe van der waals forces in general? I need some information on them and google has not been very helpful. any help would be appreciated

Is anyone familiar with van der waals forces in plasma, and or maybe van der waals forces in general? I need some information on them and google has not been very helpful. any help would be appreciated

I know that the variation in Earth's gravity varies due to the following (and other) reasons: Altitude Variations in the crust density Celestial objects Distance from the equator (centifugal accelleration due to Earth spinning) But which is the most influential and what is their relative magnitudes?

Hello everyone, I find this so contradictory so please help to understand this. In vasoconstriction, 1. The flow of blood should increase but this would also mean higher resistance so does the flow increase or not. Normally when we constrict something we expect higher speed don't we. 2. In vasoconstriction pressure should be higher but again does the resistance decrease the pressure. My questions for vasodilations are exactly the same but vise versa. Thanks for anyone who is going to help

We are getting used seeing the complicate theory of quanta be raped in every possible way by all new-age people and even by some "convertited physicist". every one sees in it what they want, so it explain karma, god spirituality... I'm kinda sick of this, and I think they have exceeded every limits This time is the Vatican that asserts that quantum physics finally give reason to the aristotelic physics (sorry Galileo ). You may think " how?". Has quantum physics discovered recently that fire goes up because it tries to rejoin himself with the sun? Has it discovered that ,in reality, the world stay still and it is the universe turning around? None of them. Vati…

V speed, cannot be V ^ 2 / t beacuse its fault

dot products, scalar products and inner products... are they same thing?

hi, Was wondering why velocity is squared in motion formulas - such as in - v = squared root of v (squared)x + v (squared)y as in projectile motion and other formulas of motion which have the variable v squared or the subject v squared. Is it do with accounting for resistance, which is like proportional (somehow) to the speed of the object or something...

Can anyone tell me the velocity of a neutrino please? I couldn't find it anywhere...