Physics

Hello everybody I live in a city where it's not always as safe as it should be, therefor I would like to start carrying a small pepperspray can with me at all times. I am paranoid that that this pressurized can would explode in my pocket. I am probably neurotic, I can't help it When I am walking around with the pepperspray in my pocket, the stuff inside the can gets shaken because of the movements of my body. Is this not slowly building up pressure till eventually one day the pepperspray will explode? How big is the chance of a pepperspray can exploding in my pocket? Is there any thing I could do to avoid the can exploding in my pocket? (for example spr…

Hi, I want to make a simple AND logic gate using transistors. I found this diagram: I believe it is using 2 NPN transistors to make an AND logic gate. I've been trying to make a simple gate with two switches but I'm failing miserably. The transistor I bought looks like this: I just can't figure out where the ground end goes and how the switches are wired to the battery. Can someone please help me out? Can someone draw out a diagram including the power source for this AND gate with the two switches and a light bulb? I've tried many times but can't figure out why the light bulb won't turn on when both switches are down. :evil: …

I have many friends that deny that law of the conservation of energy. If it were not true, what would entropy be like? If energy is being created, wouldn't coffee not become room temperature? I am new to the forums so I am not sure if this belongs in the pseudoscience area or not.

My first taxpaying job was at Sonic as a cook. They recommended that, to prevent myself from passing out from the heat, I should soak a rag in water, stick it in their walk-in refridgerator, and, when it gets cold, drape it around my neck. This made me think of an infomercial I saw some time prior: It was about a battery-powered cooling collar. They said that the science behind this was that, if you can cool down the back of your neck, the sensation will seep down into your spinal cord, and therefore, throughout your body. My question: Is this technology legit, even if the product itself (by nature of being on an infomercial) is not? If it is, then why hasn't…

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…

Hello, I came up with the idea of a space elevator being, instead of Konstantins original idea of a straight one,{lse},It Is curved outward and away from earth. In the shape of a sideways j. Obviously the chord would be rooted to the ground, and with a little "push" to launch a load off and get going, it would get into space using earths revoloutions. It would work right? getting back, you would just have to go faster than the chord Is spinning due to earths revoloutions right? Not that fast. Less energy overall? Is this good? Thanks.

Purely coincidentally, the latest film I've posted for my "Sixty Symbols" series of films about physics deals with the first nuclear test... Was intrigued to compare the two.. particularly that the North Korea test is believed to be 20KT, same as Trinity!!!? Or is that not a coincidence?

Hi All. I'm working on a project but I am struggling with temperature control. Basically, Using an element similar to that of a kettle, I need to keep the water temperature at around 90 degrees C. So what is it in a kettle that tells it to switch off at 100 degrees and how could I make/find one to switch at around 90 degrees. Or can you think of a better way of maintaining that water temperature? Thanks p.s. sorry for the poorly written question, I hope you can understand what I mean.

Quantum entanglement, as first explained in the EPR paper written by Einstein and his colleagues, seems to imply that a "spooky" connection exists between particles that have interacted in the past. Does this connection allow us to communicate faster than the speed of light?

At the risk of sounding completely ignorant and naive, I was wondering if you all could tell me some more about anitmatter. I understand that there are elementary particles such as positrons and anitprotons and that they could conceivably form "anithydrogen" (or maybe they already have?)...but what are these particles exactly? Are they made of the same "material" that regular matter is? As far as I know, the touching of matter and antimatter yields a reaction called "annihalation", right? Is this in any way similar to nuetralization reactions in chemistry, or sound waves of opposing "polarities" canceling each other out? And if this reaction (I keep calling it a …

I was thinking about the pumatic pipe packet switching networks such as the one implemented under Paris a long time ago and it occured to me that they were replaced by electronic packet swiching networks for sending information, but that they would still make a good way of transfering goods. For example dried rice could be loaded into a tube in India and next week it would be in England. The longer the pipe the easyer it would be to get a low enough presure at one end to move the tube.

This may seem like a very basic question, but... Since light exhibits two properties, can light intensity be thought of as the amplitude when it's a wave, and the number of particles present in a certain area when it's a particle? Thanks!!!

A 17 Tesla magnet being use to levitate a droplet of beer

Since my last thread was specifically referring to gravity and the 5th dimension I decided to post this new one to explore some more vaguer ideas. It is my understanding that dimensions only come in sets of threes, our X,Y, and Z. But what of the zero dimension? How do you describe an indefinitely small point in a way that makes sense? One way to look at it is that a point represents a system of no change in the next higher dimension. The line y=0 is only one dimensional system with no change in the next higher dimension, so to the second dimension the line is a point; To imagine this picture our line y=0 in x,y coordinates. The line or system takes every value possi…

I have learnt a module about phase transformation. It states that melting occurs at the melting point because the liquid can always wet its solid,mathematically, it is [math]\gamma_{SV}>\gamma_{SL}+\gamma_{LV}[/math]. I am wondering does it mean that melting can occurs a bit lower than the melting temperature because the interfacial energy also perform as a kind of driving force. In addition, can anyone think a way that make melting starts from inside the solid not the surface?

I've had it up to here with people saying that science is about explaining things. It isn't. Science is about predicting things, and any explanation is a bonus. Anyone who's studied the scientific method will realize this is true. If science were about explanations, there would not be any need for experiments to verify the predictions. I realize that when scientist say a theory "explains" something, they are implicitly saying it makes predictions. However, I'd like to ask them to avoid that since it may confuse laymen. For example, "God did it" will "explain" an object falling, but not in the same scientific sense as Newton's theory of gravity explains an object falli…

Simple question i guess, but one i dont have an answer for...

Other than simply hacking away at an object with a weapon or tossing it off a building, there are two primary ways to have an object damaged. The first is to simply use it in the way it was intended, and the object will become damaged naturally. This process is called wear and tear. The second is to simply let it sit, and the object will become damaged simply by not using it. A good example of this is an old, abandoned house. It will have cobwebs and unstable floors galore, simply due to years of not being lived in. I'm sure this phenomenon has a name, but I don't know what it is. Maybe one of you guys can tell me what it is. My question is: If all else is e…

Impressive work shown live on NASA TV; and I wonder... All those items, assemblies, tools they are handling, replacing, touching... at what temperature are they ??

Randomness is the new god. Well, I think so anyhow. To explain the result of a quantum measurement where you can predict the probability of getting various results, but cannot predict which of them you will get, it seems reasonable to say that it appears random. But if you go on to add that it is random; that is to say, that the reason you got a result is inherently unknowable (ie, metaphysical, not part of physics) -- that is an extra statement that does not explain anything new, hence could be removed by Occam's Razor. Not only that, but that extra statement completely changes the universe -- whereas without randomness the universe was considered deterministic, with eve…

I just found this (sketchy) paper on the web, and I'm curious why RF disassociation of h2o isn't considered to be possible? Let me know what you think. http://www.rustumroy.com/Scans/Observations%20of%20polarized%20MRI%20vol%2012%20is%201.pdf Thanks.

In kidsgeo they write that as air is heated it expands becoming less dense, and as a result, lighter. http://www.kidsgeo.com/geography-for-kids/0070-adiabatic-temperature-changes.php But why is that really?

So I bought a voltmeter and I hooked it up to a electric motor. I want to see how much power the motor can produce in Watts. The voltmeter reads .5 in the 20V DC mode. How much power, in Watts, is this?

in this article i was reading about how a Tesla coil works the article says "An inductor converts an electrical current (symbol I, measured in Amperes) into a magnetic field (symbol B, measured in Tesla [yes, named in honor of Nikola Tesla]), or a magnetic field into a current. Inductors are formed from electrical conductors wound into coils." http://users.tm.net/lapointe/HowItWorks.htm how is it possible to to convert an electrical current into a magnetic field and vice versa ? and by doing this is does the area effected by the magnetic field have electricity in the "air", and is that house Tesla was able with without wires or anything make light bulbs glow…

Since I am new at this, I am wondering if I am in the right place. I am in the middle of a project and have a need to better understand flywheel momentum. Can someone help me with the math and physics of such mechanical devices?