Physics

A stream of water falling down a faucet will experience the force of gravity which makes it accelerate. As its velocity increase, in order to conserve its volume, the stream will get narrower, as it travels down. My question is; is that the only reason why the stream gets narrower when it is falling from a faucet? Water molecules can form relatively strong hydrogen bonds and also the stream experiences air resistance. Don't these forces also contribute to the stream of water getting narrower as it flows down? Thanks.

Hello, I have here a Navier-Stokes equation: It represents the conservation of energy in fluids. This is going into a book I'm writing and my editor says I need to cite my source for this formula. Truth is, I got it from a website that no longer seems to be online. Does anyone know of a source (book, website, journal article) that I can cite confirming this.

Every once in a while The American Journal of Physics has an article which is a list of resourses such as a list of important experiments done to verify relativity. A list of those articles is found here http://ajp.dickinson.edu/Readers/resLetters.html Is this the right forum to post such a list?

I recalled my childhood days favorite movie called ' armageddon'. Its very very funny, might be a bogus movie for some movie goers. But i like its quick story line and stupid cinematography. The sci-fi concepts in that movie are lesser gravity on the asteroid surface. The moon jumping of neil armstrong. The space guys travel motion in zero gravity much further like as flying to some meter distance. Like as in a satellite motion, the falling object travels in a parabola like as if flying concept of ironman movie. Another thing to note that passing through time frame in zero gravity does it occur to neglify time? Or the time itself acts to slow down as gravity tend…

Two separate teams announced plans last month to do asteroidal and lunar mining: Google billionaires, James Cameron backing space resource venture. By Alan Boyle Renowned scientists join tech visionaries at Moon Express to mine the Moon for planetary resources. There has been alot of skepticism evinced about the possible profitability of such plans. However, in regards to the justification for these endeavors, several studies have shown many of the important metals for high technology such as platinum at present global growth rates, especially in the emerging economies such as China, will be depleted within decades: Earth's natural wealth: an audit …

http://www.youtube.com/watch?v=iFRKJ6PZZ3c&feature=g-vrec I for one think this could be bullshit, but since you people know more about different sciences than I do, I thought you could help me determine whether or not these "UFO" sightings were real.

Noether theorem says that with symmetries come conservation laws and so because of time, translation and rotation symmetry, EM field itself guards energy, momentum and angular momentum conservation. While atom deexcitation there clearly appears energy and (orbital) angular momentum difference, so there should be created EM field configuration carrying this difference. Photon's angular momentum is usually imagined as something only "quantum-transcendental", but in fact it is very real angular momentum. For example Richard Beth in 1936 has measured the tiny reaction torque due to the change in polarization of light on passage through a quartz wave plate: http://prola.aps…

I am trying to use an infrared LED and photodetector to make a crude obstruction sensor. The problem is that it has to work outside and the infrared radiation from the sun is causing false readings (non-blockage when there is a blockage.) I had an idea of maybe using a polarized film to block out most of the sunlight. I've read that most reflected sunlight (off of the ground is my main problem I believe) is polarized horizontally. So I would install my film (right in front of the detector) so that it is vertically polarized. Is my thinking correct or is it flawed? Any other ways to deal with the sun? Thanks in advance for your help!

I would call it applied chemistry or inorganic chemistry more than physics because there is no study in the physical behaviour of the matter but on the composition of the matter...

In church the other day my friend and I were thinking of something profound. Taking physics for a long time I thought I would find a logical answer. We were thinking about something. If there was a hole trough the earth and someone jumped in, what would happen? Would they fall through and land on the other side? Would they fall through and continue into the sky towards space on the other side? Would they fall through and get halfway and be stuck in the middle of the magnetic pull (like the earth has gravity going one way for each degree of it and they would be stuck in the middle of them all)? I chose the latter of the choices due to an "educated guess". Does anyo…

Hi, We made an experiment in class where we measured the evolution of temperature over the course of 5 weeks. I'd like to show that the increase in temperature is accelerating as summer is coming. Is it enough to calculate the slope of the linear trend over the full 5 weeks and show that it is smaller than the slope of the linear trend over the past week (increase in trends) to deduce that it is accelerating ? I'm asking because my teacher said that comparing linear trends over different time periods is not always appropriate and can be biased, but i don't understand why. Thanks.

do anyone think that time has a speed and if its broken than things will go faster and why.

ok.. simple question... I am asking for help. does anyone know how to isolate, EASILY.. CHEAPLY.. the isotopes of mercury??? I seek and desire Hg 196... which naturally.. is .15% of all naturally occuring mercury. Any thoughts??? -Mosheh Thezion

I am creating a coil gun using a capacitor bank consisting of 3 470uF capacitors rated for 500V. They charge to about 250V using a Cockroft -Walton voltage multiplier. A switch controls the amount the capacitors are charged and a voltmeter gives and accurate reading of the current voltage of across the capacitors. An SCR is in place to control the triggering of the gun, but is being shorted at the moment to test. The coil specs are Inductance = 0.673mH, Resistance=1.3 Ohms, 412 turns, 4 layers of 103 turns, 22 gauge magnet wire, turn density of 14.8 turns/cm, wrapped around a copper pipe. I tried firing a bb and it didn't even move. I'm assuming there isn't enough current…

I have prepared a draft about Stochastic scientific quantities and states. It includes the usual material (variances, medians, fluctuations, correlations), but I have added material which is not discussed in usual statistical physics literature, such as the stochastic Schrödinger equation. I have included an important remark by NG van Kampen about misconceptions regarding the concept of ensemble and some other criticism. If you find some mistake let me know. Criticism and suggestions are welcomed.

In agreement with one administrator I am posting this here. The topic is multidisciplinary but my main doubts are for physicists. I have just uploaded a draft about Open, closed, and isolated systems. I am using the standard terminology, although, in the discussion section, I notice that some physicists use a coarse-grained terminology. I suppose that their terminology is motivated by their lack of interest in problems of chemical or biological interest. I do not recommend the use of this coarse-grained terminology, because I do not find any reason for using it. If someone disagree, please state your views. I also criticize the textbook by physicists Walter Gr…

hey guys what is the entropy change in an adiabatic reversible process. i thought its 0 as U=W+Q and for an adiabatic process Q and W are 0. thanks guys

i am looking to order some super-strength magnets, but i am confused by something it says on one product it says: '26kg pull (South)' and on another, otherwise identical product, it says: '26kg pull (North)' what is the difference between these two magnets? surely they both have a north and a south pole...?

I don't know what these bowls are made of except that they are plastic but when they come out of the microwave, the bowl is hotter than the food. I thought I had read that microwaves are only absorbed by water and pass through or are reflected by other materials, which is why they penetrate the food and heat it evenly instead of from the outside inward as with conventional/infrared ovens.

If you were to throw some, lets say Volvic (other brands available) water into an ocean of Volvic water, would the water you have thrown in sink or float? I'm not a physicist, as you can probably tell. In fact, I'm not sure whether this should be in the physics or chemistry section, but I was just wondering. Thanks lol

A 60 year old mechanical engineer speaking (MSc etc etc). If space is expanding what is the opposite? You get nothing for nothing therefore a 'force' must be created for every cubic metre of space that is being created as the universe expands. Fair enough, but this means each cubic metre of space in the universe contains some sort of force that was required to create it during the original expansion? Answers in less than 1000 words please.

I know that it is a mixture of layers of glass and a polycarbonate, and obviously the more layers the greater the bullet resistance. And that you need a lot of heat and pressure to bond the layers together, what else is there to know?

When someone tosses an object into the air, the trajectory is a parabola as I have learned in Physics. But why do planets follow ellipses? I ask this since both the object and planets are being pulled by gravitational force.

Thinking about convection currents. If you had a closed-loop of pipe full of liquid, in the shape of a square, stood it uupright, and then heated the left vertical side whilst cooling the right vertical side, would the liquid flow in a clockwise direction? Rising in the left side and sinking in the right etc? If not, could it be made to do so by maaking some kind of adjustments to the set up?

In definition of matter, it comes that matter is one, which occupies space, and have the mass. Matter occupy space, meant, what ? Which are the things, do not occupy the space? (In definition of matter, is there any necessity of saying that matter is one which occupy the space ?) Why the two matters do not occupy same place, at same time ? (please try to answer by avoiding of pauli exclusion, if necessary include this too)