Physics

Hey guys, I'm struggling a little bit with this physics problem (look at the attachment for a diagram of the situation about to outline). There is a cart, upon which a block of a material of uniform density, with width w and height h rests. The coefficient of friction between the block and the cart is enough so that when the cart begins to accelerate, the block cannot slide, but instead topples over. At what acceleration will the block topple? I need to find a general solution for this situation. These are the forces I can identify: a) the weight of the block, mg (acting through the center of mass, which lays in the geometric center of the object, since it…

im doing physics in year 12. got my exam tomoro wanted to know if anyone could hook me up with a program or applet or something with a sketch or anything for equations with closed and open end pipes. and all the harmonics etc. for the hp 39g + thnks

I hope this is not considered spam as I have posted this elsewhere on the forum but wasn't sure of the right place for it. sorry if it is. To the best of my understanding materials are opaque when the energy of the photons are absorbed by the electrons raising them to the next energy level within the atom/molecule. This energy is then given off as vibrations, heat or as another photon. please correct me if I am wrong thus far. I do not know why this occurs in some materials and not others, I think it's because in opaque materials the wavelength of the electrons match those of the photons in coloured materials and in black materials all the wavelengths of visab…

Hello, Can anyone help me find out who has written on the questions of anthropomorphism in physics? I have found that even such respected physicists as R. Feynman, in his QED (perhaps his most accessible work) speaks of photons "knowing" and "deciding" whether to reflect from a glass surface. Typically, chemistry lessons concerning how electrons fill shells use language such as, "the atom 'wants' to have a full outer shell..." etc. I am trying to teach my youngster something about these matters and am struggling with the language as I don't want to ascribe an agency to atomic and sub-atomic particles that they simply don't have. This has stimulated my own interest in …

Can someone please tell me how a glockenspiel works and the physics behind it :/ Please I really need help

Is it true that blue light can interfere with signals? if so, how?

http://arxiv.org/PS_cache/arxiv/pdf/0711/0711.0770v1.pdf

Is it possible that possibly forms of matter/energy interactions only become such at certain scales? This relates to an earlier question I had about potential energy wells. I have an interest in the reality of looking at the possibility of circular or regular patterns of well interaction giving a certain regular source of energy. Such as say a global warming example. I think if you could get a system of stable or “live” wells occurring overall it would be neat if you could make it visible, say with a colored smoke or fine dust.

Look I'm sure this has been gone over again and again. But for those of us who slept through it...... How can space end?? If it does what is after it? There can't be nothing. As far as I know there is no such thing as nothing. I was thinking that if space does not end then it is all likely that there could be a so called parallel universe of type. The world as we know it is made up of a relatively small number of elements that can only bind together in a relatively small number of configurations (on the grand scheme of things). If the universe was infinite, wouldn't these binding combinations eventually reach a point where they had to repeat those that have already been m…

Being entropy is universal does this mean all work also exists or can in a potential well? What I mean about this is an example if I can from climate studies. Can a storm for instance be viewed as a potential well, or a product of for instance. I imagine multiple potential wells could be existing anytime really in a dynamic environment for instance.

Thanks guys sooo much for helping me with all my questions. Now I understand so much more. I feel really free and comfortable to talk in this forum. I am a very curious boy and I like to learn more about my surrounding world. Anyway another queston: What do you think would happen if you go at the speed of light? Would it become pitch dark because you are ahead of the light? Would you see the light behind you????

I had a question. A friend of mine noticed yesterday that the shadows formed by leaves on the ground are fuzzy little circles/ ovals. I was wondering why that is. How come the shape of the leaf is not even vaguely defined when its shadow is casted on a surface? Does anyone know? I would imagine it has to do with light scattering.

Somehow scientists have slown down light. I didn't read the whole article but I saw the headline. how did they do that?

If work is definied as: [math]W_F = \int \vec{F} \cdot d\vec{r} [/math] And the dot product is: [math] |F||dr| cos(\theta) [/math] then I have [math]W_F = \int \vec{F} \cdot d\vec{r} = \int |F||dr| cos\theta[/math] Let's say that I wanted to show that the work done by gravity on a falling object, from [math] h_0 [/math] to [math] h_f [/math] is [math] W_{grav} = - \Delta U [/math] by using the integral of the dot product above. The displacement vector is in the same direction as the force, so [math] cos\theta = 1 [/math]. Now I have the integral of the magnitude of F, times the magnitude of dr. How do you end up with a negative in front of the cha…

Hoping for a bit of insight with a problem I've been tasked with... I've tried using Z = PV/nkT and then the CS expression for Z: Z = (1+η+η²-η³) / (1-η)³ however we find α = 1/T and β = 1/P which seems far too easy. Could someone please offer a suggestion of which direction I should be looking in? Any help would be greatly appreciated!!

Ok, maybe nothing is super about this, but I created this problem when studying for a mechanics test (first year of college) and none of my friends can do it. I gave the problem to my professor, and never got a reply, hmm... Anyway, I am just really interested to see how many people could actually solve it besides me. Just a challenge. You have an massless frictionless inclined plane that is attached to a frictionless rail so that it can only move left and right - no rotation or vertical movement. It has an angle of theta, where theta isnt 0 and is equal to or less than 90. On this incline is a block of mass M. You apply a force of F on the vertical part of the i…

This thread can be for physics-related quibbles of all kinds. Sometimes persistent quibbles can interrupt the flow of discussion on an otherwise good thread. Sometime they're good--and make a valuable point, and then we move on. But sometimes they just obstruct things and promote useless conflict between people. So what I'm hoping is that this thread can be a quibble basket, for when a nitpick conflict begins to obstruct some physics discussion.

Or both really I don’t know. Simple question I think. You take a surface, spray some water onto it say with a misting nozzle or what not. Eventually the beads of water will become so big that gravity for instance takes over and they move down. Question splits to two parts and is derived from my limited understanding of QM. Does the act of gravity on the movement of such bodies basically come from gaining a higher state of energy and attempting to lower such, and is the path such takes, which appears to be random, is actually coming also from the same behavior? Now I know surface has something to do with such, but I think it would not disturb the question to g…

Does the concepts behind a false vacuum apply to the behavior of electrons in attempting to achieve the lowest possible energy state?

Why is that the concept of heat or temperature is only related to IR (Infrared Radiations), when the IR are also just like any other EM waves e.g. visible, UV, Radio etc. ? What accounts for the enhanced movement of liquid molecules when they are heated. I can imagine electrons going to a higher energy orbit on being exposed to say IR, but am not able to figure out how the whole molecules can start scurrying around on being heated ?

I recently bought a power supply off ebay, and with no surprise, isn't working right. Is there any sites that sell replacement parts for power supplies like transformers, etc. Im thinkin it might need a new transformer, but not sure though. Thanks for any help

The minimum energy carried by a wave of electromagnetic radiation is given by E=fh, right? When an object emitting radiation moves away from us, the radiation emitted in our direction is red-shifted, right? But doesn't that imply that frequency (f) should decrease? Therefore, does the minimum energy of the radiation decrease when it red-shifts? (If the answer is yes, I'm assuming energy is one of those dilating variables that relativity predicts - like time, length, mass, etc. - of course, "dilating" would be the wrong word in this case).

What are the implications of nuclear reactions, atomic power and so on in relation to QM. What I mean basically is how does QM come to bear in regards to nuclear activities of any kind really.

[math]{\nabla}{\cdot}{E}=\frac{\rho}{\epsilon_0}[/math] [math]{\nabla}{\cdot}{B}=0[/math] [math]{\nabla}{\times}{E}=-\frac{\partial{B}}{\partial{t}}[/math] [math]{\nabla}{\times}{B}={\mu_0}{J}+{\mu_0}{\epsilon_0}{\frac{\partial{E}}{\partial{t}}}[/math] Where [math]\rho[/math] is electric charge density, B is magnetic field, E is electric field, [math]\epsilon_0[/math] is permittivity of free space, [math]\mu_0[/math] is magnetic permeability of free space, J is current density, and t is time. I have a general idea of what divergence and curl are, so I have a basic understanding of what most of the equations mean. I was wondering, though, how are B, E, …

I was chatting away on a gaming server, minding my own business, when a guy in the channel mentions, "So, I can disprove movement." I was skeptical to say the least. But when he finished I was amazed... He actually disproved movement xD Anyway it goes like this. To go from point A to point B, assuming A =/= B, you'll have to go through a point C. Let's say C is halfway between A and B. What's halfway between those 2 new points? And half way between that? And that? Essentially, it's impossible to move in any direction. How about that? I understand where this is coming from. Movement is essentially time moving through 3 dimensional space. And imo it'…