random_soldier1337

Can you sum up the process of how to go about it? Also how does one go about selecting a topic for it?

No it is actually a different school. I am an international student so no such sentimental attachment. I did some looking around. Is the April 15th resolution some hard and fast rule? Maybe the ones who haven't replied yet aren't all that serious about me if it is. Should I ask the University that has made an offer an extension for time? Unless of course the resolution above really is as serious as it is made out to be. Also does the deadline of 15th April mean that the deadline is midnight on the night of the 15th (i.e. when it becomes 16th) or is it earlier?

So currently, I already have a graduate admission offer I am satisified with. However, there are some other US universities (I had only applied in the US) which still have to reply. I have to respond to the offer, I currently have, soon. I am not sure what I should do in case the remaining universities do not respond in time. How should I proceed?

Okay! One no would have sufficed . Anyway, don't you think something like teaching would be even harder for such people? I don't know how big classes are over there but where I come from they can go up to 60-70 students. Being a natural teacher to that many people might be really hard for someone socially awkward, IMO. Not to mention saving face in case such a person gets something wrong and has difficulty getting it right or not knowing how to deal with unruly students (it's a problem where I am from). To the part about industry, I am assuming that when it gets down to it, the research is dictated by what there is or would be a demand for, right?

So basically, the PhDs appointed as professors at universities or group leaders in industries get to propose the actual project while the technicians/analysts/etc. are the ones that actually do the experiment and hand over the collected data? Therefore, the job becomes filled up more often with stuff like teaching for the professors or writing for grants in general, right? Also how would one go about getting the rare dream job in the research labs? Research always seemed like a great profession for someone who is less social but wants to achieve something, theoretically. But some of those responsibilities definitely don't sound like such a person would be able to do well, especially if they had to do something like teaching. How does one do the latter?

I suppose I should be more clear. I understand that some might study particle physics at the LHC and some might study glacier drifts in the arctic region. I also understand that somebody studying polar bear migration patterns throughout the year in the arctic may pretty much never do any teaching since they are always in the middle of nowhere. I am primarily concerned with the secondary responsibilities that most researchers have. I want to know what are the jobs they have to perform during their time as a researcher that are simply not them and what they are observing.

As in do some researchers possess certain responsibilities while certain others choose to undertake different ones? Like some more on the theory and relatively more paperwork while others more involved with the experimental setup of their theories. Or do all share more or less the same responsibilities and duties? Either way, what are they and which are the more social ones (teaching, etc.)?

That's a bummer. I thought I had missed something. I would like to know what would you do if you had to simplify an expression. Further simplify or stop at this point on account of making an expression incorrect? Or does it depend on context like initial conditions for integrals or something?

So what I thought I knew years ago for some reason I am confused with right now. How shameful! Wonder which marble I lost? I must have had a brain fart. Anyway, the identity goes (a - b)2 = a2 + b2 - 2ab Going from right to left, without knowing the left side, how would we know whether the negative term is a or b?

You have done your studies in law? You seem to have a greater interest in science seeing as you hang out here and I didn't ask too many high level physics questions but you seemed to answer them quite appropriately when I had asked earlier. What's your story if you don't mind me asking?

I had applied to several universities and got a positive reply from the University of Florida for the program in MS Nuclear Engineering. Anyway, these are my questions: 1. Is there anything I should be aware of in particular about the university, the program at this university or the region in general? Whatever you guys know is fine. It would be too much of me to ask everybody detailed info on this. 2. My undergraduate background is in Electronics and Communications so that might make people a bit skeptical. However, I have this admission offer now. They must have seen something and regardless of what it is, if something trivial, I will not back off from any and all work it takes me to make the most of this opportunity and beyond that. What preemptive measures can I take prior to joining to ease myself to the greatest degree into my studies? 3. The letter says that I have to respond by April 15. Obviously, I am still waiting for other responses. It is not possible that they would rescind the offer prior to that date, would they? 4. What is the research scene like at this level? My thesis will be the most important, I believe, but is there anything else I can or should do during my MS to improve my credentials as a researcher in this field? I am not particularly familiar with the process it takes to become a fully fledged and recognized researcher. I only know a few bits and pieces such as you have to work well with other recognized professionals in the field on their research projects, internships during summers/after the program, perhaps submitting some papers of your own (though, you have to be affiliated with a recognized institute in my understanding). However, this is a bit vague, so is there anything that I should specifically be informed of? 5. How exactly does writing a thesis work? And how would I find a suitable topic to write one on? Or hot topics for research in general? 6. Given my background, is there an heavy obligation to draw from it at the university, in my studies or otherwise?

That sounds like doing more than necessary. If the gun is sighted such that while aiming it points slightly upwards, then why do you need to aim a little below target? Why not just directly at it if the gun is already sighted to compensate the gravitational pull? I don't actually know anything about guns. The little bit that I do know comes from video games and that isn't reliable at all. Look, for the sake of simplifying the explanation, let's just take one of the very first hand guns such as a revolver, the likes of which were used during the time of the cowboys. No fancy scopes or adjustments, just the gun and the marksman. What about these? Then once an explanation is made for a simple, old time, revolver, can you guys please try to explain how a modern high tech sniper rifle would/does work? From the sounds of all the calibration that goes on and from what I heard elsewhere, a marksman needs to adjust the sights and what not while thinking of the various factors that could affect the trajectory of the bullet. Also from google, apparently some of the adjustments need to be made by a gunsmith and can't be made by the shooter in the middle of the field. For the purpose of this explanation, lets also say that a soldier given the top of the line sniper rifle is in the middle of a combat situation and is trying to get as many kills without getting killed himself (hopefully he is at least taking potshots from a good hidey-hole). Now what with all the calibration that needs to be done, how is he supposed to fare in such a situation? He has to shoot over a varying number of long distances for which, from what I understand so far, he may or may not have to make calibrations. How is he supposed to quickly and efficiently go about taking accurate shots?

If a gun is aimed while the barrel is perfectly parallel to the ground and the ground itself is perfectly even, then how is it that the bullet lands where the tiny bit on top of the gun was pointing?

@imatfaal, I think I understand. I just went for my method because I wasn't really thinking that far. Also just in case anyone else refers to this thread in the future, the 676 m in my initial equation was listed on the wrong side as well but other than that, the amendments made to the initial attempt get the correct answer.

@imatfaal, That is indeed the correct answer. I just don't understand how the assumption for the single root could be made. With that assumption in most cases generally, the answer we may require (even if only one), would change by putting the discriminant as zero, if there are two roots, wouldn't it? How then could we guarantee that whether the assumption would be correct? It worked out here but how do we know generally? I also don't understand how my method did not work. Isn't it implied that the acceleration should be large enough that the train should stop just before touching the locomotive? Then we could use the equation for final velocity to replace time in the quadratic and find the acceleration from that. I got -0.946 m/s^2 (so close yet so far!) and both of the sides are equal in the original distance equation the quadratic was derived from (approx. 1057 m).

@imatfaal, Yeah, I believe the textbook itself has stated a wrong figure. If the assertion that the car ends at rest is taken, then it takes ~46.9 s after the first ~12.8 s to stop from the speed achieved during the first 225 m but it stops at 825 m. If it is assumed to stop at 675 m and either of the times is used, in the case of ~26.9 s, the car is not at rest (~15 m/s) at 675 m and if the time is taken as ~66.9 s, the final velocity is ~ -14 m/s which doesn't make any sense. Well at least for the method I used. Maybe one or the other figures given in the statement needs to be changed. Anyway, thanks for the info. I still don't know how to do the third one, though.

So basically, it was qualitative? And people would basically say that, "So and so has been seen to bear this much weight but I can't say about more." Or something to that effect I take it. But don't atoms have angular momentum? Also I never actually asked why rotating objects can't be point objects. Why is that so?

Well, to put it differently, is there ever a practical physics problem where the model of simple kinematics in linear motion apply? 3) Well... it didn't specifically say the time period. I'm guessing unless otherwise specified or needed to be observed (as in that is where the answer is), 0 to +infinity is the time period to observe. 4) If even now instantaneous velocities and accelerations are derived from either graphs or other indirect methods, then how do speedometers work? I have a hunch it is the same indirect way either with some sort of spring mechanism as you said or electrical transducer or the like. Well I'm just curious how one without access to industrial machinery of any sort would do their own experiments, back then or even now, like say measuring the force required to bend an iron rod of some specific dimensions or the force required to cause a fracture in a rectangular baked clay brick.

So in general, it will not work for more practical cases, where one is trying to describe the motion of most realistic objects?

1. Oh right! I was right all along. Should have known that. Silly me! 2. I don't know how you are getting those values. I even checked the zeros of that same curve graphically with my TI-84 calculator and the zeros occur at roughly the same time as the values I had previously calculated by hand. According to the calculator they are 67.001661 (bad approximation since the y-value on the calc is 10^-10) and 26.865006.

And one practical one. Hope this is the right place since these are mostly beginner questions. 1. When can we treat objects as point masses/behaving like particles for the sake of simplification of calculations? I ask this question because my physics textbook said that a stiff pig sliding down a slide could be treated as one whereas a tumbleweed could not which I'm not quite sure about. I would think that the pig's limbs and snout jutting out would cause changes in its motion due to the collisions with the slide. Likewise, isn't the tumbleweed a relatively cohesive mass? Maybe if one were to analyze the movement of the tumbleweed itself, I would think it would matter more then but not when its motion is being analyzed relative to a surrounding. Anyway, what can you guys tell me about this? 2. If two objects are in freefall in an ideal vacuum and ideally constant gravitational field, is it absolutely true that the two objects will fall at the same rate? As in nothing short of a constant force applied in the opposite direction will change it's rate? Maybe I've been conditioned to look at objects falling in our atmosphere but is there really nothing like an associated rotational motion to the object or anything that would change its rate of freefall? Or is that just a beginner's simplification/concept? 3. When do we observe the negative x-axis? I ask this question because a question asked me to find the maximum positive distance achieved by a particle with motion defined by the equation x = 12(t^2) - 2(t^3). Graphically, that would be +infinity at the time -infinity. But the answer is a finite value at t = 4, which is 64. Hence, my question. 4. How were instantaneous velocities, accelerations and forces measured before modern times i.e. without any digital indicators or industrial machinery and the products thereof? And did these give numerical values or only a qualitative indication?

1. Question: Rachel walks 2.80 Km to a gym at 6.00 Km/h. Upon reaching, she walks back the same distance at 7.70 Km/h as the gym was closed. Find her average velocity. Attempt: I find the total time by: (2.8/6)+(2.8/7.7) ~=0.830 h. Divide 5.6 by this to get approximately 6.74 Km/h. First thing I am confused by is, why is the average velocity simply not zero since her displacement over the entire time period is zero? (I actually calculated this since the back of the book gave a finite answer) Second can someone please confirm this answer? The back of the book says 3.27 Km/h but I don't know how that would be achieved. 2. Question: A car moves 0 to 900 m, starting and ending at rest. Through 225 m, it's acceleration is 2.75 m/(s^2) and through the remainder, the acceleration is -0.750 m/(s^2). What is the total travel time of the car through the 900 m? Attempt: For the 225 m, from x-x0 = v0t + 0.5a(t^2), 225 = 0.5(2.75)(t1^2) => t1 = sqrt(1800/11) ~= 12.8 s. Find initial velocity from this for the rest of 675 m as v = v0 + at => v = 2.75sqrt(1800/11). Then from the equation for distance, 675 = 2.75sqrt(1800/11)t2 - 0.5(0.75)(t2^2), which is a quadratic and I solve it to get either approximately 66.9 s or 26.9 s neither of which help since the solution is around 55.2 (actually I had to use a solution book for this which uses slightly different values and gives 56.6 s as an answer, FYI). However, when I assume the 675 m to be covered in reverse so that the equation formulated is basically in reverse i.e. 675 = 0.5(0.75)(t2^2) this gives me t2 = sqrt(1800) ~=42.4 s, so that total time is 55.2 s. So you can see why I am confused since I actually used a hunch to arrive at the answer and don't actually know what the correct method is i.e. consider the motion of the 675 m in forward with a finite initial velocity or in reverse with zero initial velocity? 3. Question: A train traveling at 161 Km/h, rounds a bend and the engineer is shocked to a see a locomotive 676 m ahead traveling in the same direction, on the same track at 29.0 Km/h. The engineer applies the brakes immediately. What must the constant deceleration be if the collision is to just be avoided? Attempt: 161 Km/h = 805/18 m/s and 29 Km/h = 145/18 m/s. Dl = Dt + 676, where Dl = distance covered by locomotive over time to near collision and Dt = distance covered by train over time to near collision. Replacing values according to the formula for distance covered with constant acceleration, I get the equation, (145/18)t = (805/18)t - 0.5a(t^2) + 676. Since I need to find the acceleration I assume that the train wants to reduce speed to 0 m/s and from v = v0 + at => 0 = (805/18) + at => t = -(805/18a). Then replacing this value for t in the earlier equation, I basically solve for a and get a ~= 3.91 m/(s^2). Seems reasonable but it is not the answer according to the answer book and when I replace this in the first equation to get a quadratic equation to help me find time, I get t ~= 30.2 s but replacing this in the original quadratic, the sides are unequal. I have tried checking where I went wrong but I cannot find the answer, not to mention that I did not have much of an idea of how to proceed with this question to being with.

@blue89, I guess I've covered till five and maybe some/most of 8 in your list of mathematics. For the sake of my knowledge in physics, I think it's better to just assume that I studied till high school level. As for the remainder, I am sorry but It's really hard for me to understand what you mean in this part: @studiot, My interests i.e., fields in which I want to pursue further studies (now that my bachelor's in Electronics and Comms Engg.is done) are: 1. Particle Physics 2. Quantum physics a. Quantum information science (computing, information theory, etc.) b. Quantum Field theory/Quantum gravity 3. Nuclear Physics/Engineering/Technology or Solar Physics 4. Photonics 5. Photovoltaics 6. Astrophysics 7. Condensed Matter physics 8. Dynamic systems theory (Control Theory, Chaos Theory, Quantum chaos, etc.) 9. Neural Engineering 10. Study of Complex Systems 11. Nanotech 12. Metamaterials Though, that's probably not the most important thing at this moment. For now, the most important is for me to give the Physics GRE (I also have to give general and TOEFL as well as a side note just so you know where my other time is going) which is why I need help in building some sort of a streamlined plan to study for it. I just got Halliday and Resnick for general as well as Modern Physics by Krane. My plan was to cover these two first so that a fairly large chunk of the exam is doable. I have planned on obtaining texts for more specialised topics like thermodynamics, mechanics text (with Hamiltonian and Lagrangian mechanics), etc., but the thing is that I have studied electrodynamics as part of my Syllabus in engineering and it was very involved/time-consuming and very little knowledge of it, if anything, has remained with me which is why I thought it better to cover the general texts prior to specialised texts. Most of them seemed similar to the text I had to refer for Electrodynamics (DK Cheng) so I wasn't really sure how to cover the syllabus for the GRE in time if I decided to get into the specialised texts.

I can't seem to find it. Just a lot of videos and text covering the concepts. Can you give me a sample? Most of those courses seem fairly advanced and specific. Anything starting from the basics? I know basic calculus and have studied physics in high school. I think I can spare maybe some 3-4 hours daily. I'm not sure how answer that personality question but I can be patient if I need to be. I have just graduated from college and again I don't know how to answer that question on economic status.

Covering concepts is not too much of a problem. Finding practice questions is the bigger issue and the right ones, at that.