Physics

I'm in first year of physics in my high school but I really don't get this concept. Say I'm on scale and going up on the elevator with a positive acceleration. Then my force is F = m(a+g) But my teacher told me that it's different if the elevator is goin' up and slowin' down or if the elevator is goin' down and speedin' up. I do not get those differences in terms of Force. Can anyone explain it? Example will be nice. Thnx!

Here I attempt to show how if you understand what distance *really is* then you understand what everything *really is*, in nice, mathematically precise terms. Oh, and you also need to understand some calculus. The explanation for the title is that it is a salute to another poster who likes to tell us what stuff really is. Each definition is given in terms of previous definitions and physical laws, though I have occasionally added an alternative definition which doesn't, but serves more as clarification. Except, of course, for distance distance [math]\vec{r}= ? [/math] Well, I don't actually understand distance, unless we are talking about a flat space (which doe…

Hi, I would like to make a "floating" thingy experiment, I'm new to this forum but I've always been curious to science, I have two ring shaped magnets (found em in the trash) one of them is pretty strong and the other not so much, So any advice? I'd like it for a "desktop ornament", not my PC desktop of course..

Does a unitary operator itself denote that a finite amount of stuff exists in the universe?

can some one please explain to me the structure(s) of an atom? (i know its a very "open ended" question... but i really don't ave any clue were to start.) any input at all is a lot of help thank you

Is the size of an atom in relation to say electron movement part of the reason we say wave particle duality. What I mean is electrons in an orbit are to move rather fast, and at the distances such objects are moving would it almost make time non existent? I mean to move a billionth of an inch at almost light speed for example. The amount of time there I think is my question, simply put if time for instance is basically an abstraction of material reality reacting for instance, well at such scales would not time also be different then say time for a massive star?

Usually a periodic force is used for the forced vibration. However when the potential is not harmonic, we often get insufficient amplification by the periodic force. In that case the aperiodic pulse excitation might be effective. I tried to simulate how the non-linear oscillator is excited by pulsed external force in the follwoing site; http://hecoaustralia.fortunecity.com/forced/forced.htm

I've been toying around with an apparatus for levitating my magnets of ownage (you know what I mean; neodymium rocks!). First off: Is it a better idea to try to levitate the silver dollars or the magnets themselves? I have a greater volume of silver, so I'm guessing I would levitate the magnets. Next: Since I don't have access to fancy building materials (obviously true; I would have bismuth otherwise...), how can I get a stable system of levitation set up? I've been just dangling magnets over the makeshift lump of silver coins and magnets. How can I improve upon my primitive method? By the way, anyone who hasn't tried this but has magnets and silver, just try wavin…

Hey everyone, I'm new to the forums, this my first post. I'm working on building an electric power generator using rotating magnets. I'm trying to work every thing out on paper before I start building, but I'm struggling with the equations. Say I have a three magnets of arbitray strength rotating within a solenoid with arbitrary length and amount of coils. What equations specifically would I use to calculate the amount of electricity this system could produce? I assume the speed at which the magnets are rotating matters, as well as what material the wire in the solenoid is made of, say I'll use copper. I know this has something to do with Faraday's Law, and magne…

Can anyone Please help me with this problem? I'm trying to use this formula (velocity = radius * angular velocity), but somehow it's not right Thank You. The diameters of the main rotor and tail rotor of a single-engine helicopter are 7.60 m and 1.02 m, respectively. The respective rotational speeds are 450 rev/min and 4150 rev/min. Calculate the speeds of the tips of both rotors. main rotor? tail rotor? Compare these speeds with the speed of sound, 343 m/s.

I am not great at physics... Can you help me with one problem, or just explain what should I use to solve it, which formula. Oops.. it probably should have been in "homework help"

does sound really pass through strings? my best example for this is the "telephone cans" which is made up of a string and 2 tin cans. children use it as a telephone, the cans act as their mic and speakers while the string connects the two cans.

I have been trying to preform the "HOT ICE" experiment lately and it just has not been working, and i would love some advice on what i might be doing wrong or if its just not possible... HOT ICE experiment ----> can some one pleas explain what is happening here? so i might have a better understanding of were i am going wrong.

Right, so I am taking a physics class this semester. Most of it is just reminding myself of my Highschool physics, but I encountered a conceptual problem I still remember struggling with in High School too. Disclaimer: I have no problems understanding the *formulas*. That's not my problem; I can either memorize them, or add them up to my formula page. The "what is torque Mathematically" is not the question here. What is Torque? Physically. Can anyone please explain to me what is this force? I understand it is created by rotation, but I can't manage to imagine it, or understand how I can 'feel' it. If I rotate something around my hand - like a wheel - where …

I know the earth absorbs matter from the universe and I imagine some matter escapes. I'm gonna guess and say the earth is gathering more than it lets go. Would raises a question of mine. A certain number of things have to stay generally the same for something to stay in orbit right? Like size, speed and distance from the object it's orbiting. The sun is pulling the earth in as the earth is trying to get away at just the right amount to keep earth in orbit. My question is how much can the earth gain or lose before the orbit is dangerously interrupted. I read or heard somewhere (maybe it was this forum) that if we ever mined on the moon that we would have to be careful how …

Well, the title speaks for itself really. This is a reaction to a post made some time ago about what element fire was. Well, it's plasma. But how much does it weight? Or, to be more precise, what is it's density? How do you measure it? If it even has a density, does that mean that when you blow at a candle and the flame gets smaller, it's density increases? Or does the energy somehow dissipates? Thanks in advance for any and all answers.

What can be expected if we lived on a heavier planet? The stress on the body would resemble weight lifting on this planet wouldn't it? I'm not sure if muscles would grow stronger or just die on us and even if we did grow stronger if our bodies would get worn out quicker. I'm wondering if we would have any other troubles biologically? After some generations we'd develop an equilibrium like we have here on Earth when we are at rest wouldn't we? How much of a gravity boost can the average person handle before they just can't even get themselves off the ground? Would everyone end up being ripped or would our muscles change so that they don't have to be as big as they do on Ea…

Just woundering about fire? what element is that, eg. solid,liquid,gas,etc sorry I don't know if its the right section

Can we call the outcome of a chaotic phenomena like for example evolution or weather to be random? Isn't such an outcome just unpredictable due to inherent nature of numbers and other not so precisely defined factors but not random? Is it right to say that the unpredictably arising in chaotic system is just unpredictability while the unpredictability which is a property of quantum system is actual randomness? Please discuss. Thanks!

http://www.metacafe.com/watch/877471/bunker_buster/ why does the blast get sucked back in like that?

I'm wanting to calculate the experimental uncertainty in the following function: N = f(x,y) = a*exp(-x/y) where a is a constant. I've applied the following technique: For z = f(x,y), Δz = sqrt[ (∂f/∂x * Δx)² + (∂f/∂y * Δy)² ] And calculated: ΔN = sqrt [ ( (-a/x)*exp(-x/y)*Δx )² + ( (ax/y²)*exp(-x/y)*Δy )² ] However this is giving me an error far in excess of what I should be getting... can someone advise where I've gone wrong?

I have a friend who is an experienced photographer. He said that an exposure with the "same bucketful of photons" at high or low level for a shorter or longer time with the same aperture, yields pictures of discernably different quality. The low-level exposure gives a clearer picture, and I am curious why.

Well, I have technically two questions and they are as following. 1.) I found this diagram which I'm sure many of you have already seen, but it's a diagram of Nikola's Tesla's famous no wire light bulb. http://upload.wikimedia.org/wikipedia/en... the website for the picture. Anyway, I was just wondering if anyone could please explain the diagram and the parts and of course if anybody knows, how it works. As I am a student trying to research upon this topic, I was wondering if anyone could please shed some light upon whether this could be easily built and if so how, and any tips or experiences. 2.) A PHD student at MIT (which im sure many have also heard of) has …

How do we do physics without forces?

I would want if you guys can tell me whyand how do forces occur?? Thanks:doh: