abskebabs

Gotta love Jon Stewart:-) . I think the Celine Dion stuff may be part of Hilary's effort to reach out to the unmarried, single 25-40 year old female demographic, which was identified by political pundits recently as a major one. I'm not sure I really like any of the candidates tbh, none of them seem completely genuine, and even Barack smacks of political oppurtunism. I think I liked one of the lesser known Republican candidates but I doubt he'll get anywhere. Also I'm not even American, so I have no vote on this anyway!

I'm sorry to be pretentious but the correct expression for what you are referring to is a newb, not a noob. The latter is usually referred to ppl who may not necessarily be profficient at what they are doing, but think they are, and in the process pester and annoy others in various ways. This is as far as I am aware anyway:cool:

Even if so, this would be at best patronising and disingenous, and at worst downright manipulative, I guess the lines of morals are probably pretty blurred for a lot of politicians anyway... Even if this were the case, I would have liked to think that if there really was a much more sophisticated goal behind the attacks and occupation of Iraq, the policiy would have been implemented in a much more thoughtful and carefully considered way. Don't you think so? Or perhaps I and most of the world has been expecting too much of governmental forward planning and management skills... Who knows, perhaps one day you will be able to say the word bureacracy without inadvertently synonmising inefficiencey, incompentency and corruption?

If this is the case then I would recommend "Mathematics and the Physical world" by Morris Kline, as personally, this book has inspired me a lot in my studies of Mathematics even though it is a little dated now.

I'm finding the last paragraph of your post incredibly awakening. You mention that obscenities help us "blow off steam", I mean, I would guess that this probably extends beyond the verbal domain. Do you think that ppl like to watch violence or unfair humour to release some sort of "primal tension?" I dont mean this in a personal way at all, I am just purely curious about the possible extension of your point. I can see how it could work in other ways, for example association with obscenities, may help allow their acceptance and this would then be followed by their practice. Also it depends if this kind of behaviour is at all tolerated or sponsored by perceived higher authourities, e.g.; parents, teachers, government etc. While reading this thread I have been wondering myself, if this kind of study, though the grounds or means of which may be ethically questionable, as I feel JohnB has correctly pointed out. However, I dont know much about the actual investigation itself, as has already been alluded to so: Perhaps the intention of this kind of thing may have been made to actually investigate the audience and their own responses to this kind of video. If anything this would be where any material valuable to their research could be found. If this is not the case, then at the moment I am puzzled as to how it could really be called research. If the research is genuine, then perhaps the goal is genuine but I think from what I perceive so far the methods are unnaceptable, but then again; as Pangloss has pointed out we lack information about consent and how other issues have been tackled. Within a controlled scenario, and in a strict context such work could be acceptable.

I guess it can be "shown" to be true, by using some logical mistakes along the way, as has already been shown. I wish they taught me about this stuff at school, so I would know about how basic truths are derived from axioms and be able to apply the logical process involved. It is one of the many neglected areas of mathematical education IMO.

I agree with you strongly, it is much more meaningful to ask a relevant question that you yourself are actually interested in; about or related to the other person, and to give a s**t about the response. You have to be personal, this is how we get to know people in the first place! It's not about you being the most interesting and entertaining person in the world, it's about exploring and appreciating the real things about the people you get to know, and then being honest about your feelings for them, whether friendly, sexual or whatever. Despite this being a thread for lame ass chatup lines, I think what you have put up in your post is much more helpful than anything else I have seen in this thread:-)

Alan2here this is the fundamental principle of relativity, the laws of physics are the same in all inertial frames of reference frames, and by consequence, light propogates at the same speed in all inertial reference frames. The situation you mentioned involves an inertial frame of reference travelling with respect to some other "rest" frame(presumably Earth's), so of coursea person in the ship would observe no difference in how light propogates. The bit about a tennis ball I'm a bit more cautious to answer, but I suppose if you're ship is generating its own gravitational field, there may be no observed difference with throwing a tennis ball up in the "air". The principle of special relativity, is really just a revision of Newtonian relativity. Think about travelling on a steady train at constnt velocity with respect to the ground. Is any difference observed by you when throwing a ball up in the air and catching it, to the doing the same thing on the ground?

I've just completed a first year course in Quantum mechanics(more of an introductory course I would say), and I think you can get by just fine with a basic knowledge of mathematics, differentiation, integration and already with a familiarity with some of the conservatin laws of mechanics. The abillity to solve ODEs, or at least understand how the solutions are obtained and why they make sense was sufficient for me(though personally I prefer solving them). Quantum mechanics does involve PDEs too though, especially the time dependent situations so a knowledge of that will be required too as you get more advanced. Also I agree with the comment about linear algebra, though personally I have not had to use it yet. I think the early quantum theory is not too hard to understand as long as you're comfortable with a little calculus and manipulation of equations. The first few things learned are just the basic principles. A little pre-existing knowledge of wave physics may help a bit too. Once you have the basics sorted out, I would recommend Quantum Mechanics by Alastair Rae. Also a decent website, I would not recommend to learn from but which can be useful as a reference to clear up doubts is hyperphysics. Just search for it in whatever engine you prefer, you'll find it:).

If you haven't joined uni, then it might not matter which you initially pick, because if you change your mind you can easily switch between the 2 courses before the end of your 2nd year, as in most cases ther won't be any difference betweent them till the 3rd year. Apart from that I concur with Klaynos' statements.

It's ironic in a way. A problem originally involving particles cannot get a unique solution unless we consider the shape and relative size of these particles, which initially we neglect. It seems you cannot have a full mechanics for idealised particles, even though they help a lot in simplifying a problem. They do not seem to be self consistent concepts, at least in classical mechanics anyway.

lol:D

Interesting. I'm guessing the angles you are mentioning here are the angles from the line of the momentum vector of the original moving particle right? Also can you perhaps elaborate in any more detail how mathematically we relate a function describing the shape or cross section of the surfaces to the distribution of velocities resulting from elastic collisions that occur between objects?(In CM of course) I have to say its nice learning about the little details or "digging deeper" here:-) .

Hi every1. After my exam today I decided to drop off at the card shop in Uni to buy a sorry card and a chocolate dessert. When I got back to my flat later on, I got the card out and wrote on it how sorry I was and how much I regreted breaking her trust. I also told her that though it didn't make up for what I did, I left for her a chocolate dessert in the fridge. I'm glad to say things turned out ok:-) . About half an hour later I saw her in the kitchen, with 2 of her friends who had come over to help prepare for a dinner party. She immediately told me she saw the card I slipped under her door and gave me a hug and even kissed me on my cheek. Tbh honest I was blushing and even a little uncomfortable. I told her I'd also left her a dessert but she said it was fine. I'm happy again:-). Thanks again for your advice.

I'm sorry to be pedantic, but I acknowledge that if the problem is underconstrained there will be a continuum of possible solutions. I'm guessing therefore from what you have said that each of the infinitude of outcomes will be of equal likelihood, given unconstrained conditions? More mathematically this would mean that if I tried to plot the probabillity density function, I would get a flat line. Is this true or not. If not, is the function that describes the probabillity distribution, whether discrete or not, known?

Even so, by the equations above we shouldn't need to specify this. Each of the solutions the 2d and the 1d should be possible without further information required to gain solutions. If what you say is true, is it really just an exposition of the limited applicabillity of the basic equations of classical mechanics like the ones above which do not take into account the extra information you have mentioned. If a particle hits another particle at rest shouldn't both the 2d and 1d trajectories be possible after the collision? Indeed if we carried out an experiment, shouldn't each of these trajectories occur. If not, I guess you're right and the architecture of these equations need updating. Is there a version of classical mechanics that incorporates this kind of extra info, e.g. lagrangian or hamiltonian?

Maybe they find it funny when the drivers get infuriated drivers and descend into a blearing, insulting frenzy. Ppl can be very silly sometimes(I am no exception to this at all). Personally, I often could not help but smirk or giggle after I got yelled at by my teachers at school sometimes, but I guess this may have been a product of my immaturity at the time.

Hmmm... why would this be? There are no external forces involved in any of the equations, so why would the absence of an external orthogonal force cause a 1-d trajectory to be followed by the particles? I can understand why with external forces orthogonal to the original particle's velocity, it would be imposible for there to be a 1-d trajectory, but I cannot your statement above.

Right! I see, the one dimensional case is a perfectly valid special case of the general solution to the problem. Of course you would get a possible solution being that the vector sum of the velocities remains unchanged, and the magnitudes of one of the velocities equalling zero, thus satisfying the the fact the identity you have quoted is true. Just out of curiosity though, I would like to reiterate the question I had stated in my last post. Is there a difference in the likelihood of these events occurring? For example is it more likely for the particles to take a trajectory perpendicular to each other after a collision, than the moving one coming to rest and the one initially at rest moving off at the original velocity of the 1st one?I guess that both could be equally likely, but the 2nd case where velocities are perpendicular would become much more likely as there would be far many more possible outcomes for which it could be true. Is such a conjecture correct?

I was thinking along the same lines actually. You could equip a breathalyser to the ignition so the vehicle will not start if alcohol is detected. There are ways that this could be manipulated though. Someone could just get a sober person to breathe into the breathalyser, but then both of them would be implicated with the crime, and I think there would be a heavy penalty on the sober person. Also, someone who has drunk alcohol could maliciously hamper someone else's car by breathing into it. I actually got a lot of this, especially the last point from watching an episode of scrubs:D .

It was her who made it nor her mum. Thanks for the advice btw, I will carefully consider it before deciding what to do. Also we're in student accomodation so there isnt the possibillity of kicking someone out, I just feel really bad, and so I should I suppose until this is sorted out. Also I don't mean to make myself sound better by saying this but the 2 other ppl who took some of the cornflakes themselves have not admitted to it, and I don't think are bothered by what they did at all. I feel like this is a bit of wake up call. Somehow, I think telling her it was delicious while apologising might just piss her off even more, I don't know...

I see, so does that mean that the 1st result only applies when motion is constrained to one dimension? I realise that the word orthogonal has no meaning in 1 dimensional motion. Actually, as opposed to what I have just put above does this mean that the vector sum of momenta in the original direction of motion of the ball after the collision equate to the momentum of the moving ball in that direction before the collision? I can see how such a result would could actually make the results of both equations consistent. Actually that would depend on the angles of each of these from the original direction of motion, as well as the individual magnitudes of the resultant momenta. I guess there are a lot of uncertainties involved in examining even elastic collisions. Do these equate to probabillities, if we carry out a statistical assessment of an experiment based on this? I guess it would be intriguing to find if the individual outcomes are equally likely if the above premise is correct. If not, things would become very interesting I think...

Imagine we have 2 equal masses, one at rest and the other coming towards it at a velocity v. If we take Kinetic energy to be conserved during the collision, and therefore that the collision is elastic we can analyse it in 2 different ways and yield different conclusions. For example, if we look at what I will call the 1 dimensional case: [math]mv=mv_1+mv_2[/math] Where [math]v_1[/math] and [math]v_2[/math] represent the velocities of both masses after the collision. As the masses are equal, we can say: [math]v=v_1+v_2[/math] Also as energy is conserved: [math]\frac{1}{2}mv^2=\frac{1}{2}mv_1^2+\frac{1}{2}mv_2^2[/math] Therefore: [math](v_1+v_2)^2=v_1^2+v_2^2[/math] So: [math]v_1^2+2v_1v_2+v_2^2=v_1^2+v_2^2[/math] As we can see, for this to be true we need either [math]v_1[/math] or [math]v_2[/math] to equal zero. Therefore, if the collision is elastic, and the ball that has been hit starts moving, it will have all of the other ball's original energy and momentum and the other ball will have stopped in its tracks. Notice motion is confined to 1 dimension in this case. We can look at this problem slightly differently however, if we look at the vector properties of momentum. If:[math]\vec{p}=\vec{p_1}+\vec{p_2}[/math] and we take the dot product: [math]\vec{p}\cdot\vec{p}=p^2=(\vec{p_1}+\vec{p_2})\cdot(\vec{p_1}+\vec{p_2})[/math] Then we get: [math]p^2=p_1^2+2\vec{p_1}\cdot\vec{p_2}+p_2^2[/math] If we now divide both sides by 2m to get an expression of the total Kinetic energy: [math]\frac{p^2}{2m}=\frac{p_1^2}{2m}+\frac{p_2^2}{2m}+\frac{\vec{p_1}\cdot\vec{p_2}}{2m}[/math] From observing the equation, we can see that if the collision is to be elastic the last term shown above has to equal zero. Therefore the dot product of both velocities after the collision has to equal zero, so that both particles will recoil from the collision travelling at velocities orthogonal to each other, as opposed to one stopping and the other moving. As can be seen both results are different to each other. My question is how can they be reconciled? Also is the 1st one just the result if the collision is constrained in a situation where only one dimenson, and which of these results would be valid in a "real" elastic collision?

Fair enough, also I think I should stop using these smiley faces so much. About buying her another box, the problem is these were homemade. Could I just get her a "I'm sorry" card or something like that?

I guess this may be considered a minor issue but I decided to post it anyway. The other day, me and my 2 of my flatmates were looking in our fridge when we noticed one of our other flatmates had left some chocolate cornflakes in their(my other 2 flatmates draw). They decided to take one each, and just pretend that if someone asked they would say they thought it was each other's. In the process I decided I would have a piece too, justifying myself by thinking that I didn't take it out of the fridge, and I was having what was already taken. it was delicious btw:-) . However, I am also pretty much incapable of lying, as I cannot do it(in the long run I guess its a good thing) most of the time. So when my other flatmate asked me if I knew what happened I tried dodging the question, but ended up telling the truth. Now she's understandably pissed with me, and says she won't forgive me:-( . I guess the issue more than anything else is trust. I consider myself quite good friends with her so I have betrayed whatever trust she had in me. The fact I told the truth doesn't make up for what I did. But thinking about it I think this just exposes a flaw in human character, and makes me think of how important forgiveness is as we are all susceptible to our flaws. I suppose you may think I am making a big deal out of nothing, but what's your take on this? Also any general advice? Cheers