• Physics Discussion
    973 replies, posted
[QUOTE=acds;39521632]I'm actually really torn on whether to take a PhD or not. On one hand, researching and shit is cool, on the other it's 4 more years, I don't really want to spend the rest of my life researching, and you don't get paid much (30000SEK/month here, but you also lose 4 years of experience which are a pretty big deal). Plenty of time to chose, but you can't know what route to take too soon.[/QUOTE] Sounds like you are in quite the pickle. If you could do anything on this green earth, what would it be?
[QUOTE=Mr.SpicyTornado;39522011]Sounds like you are in quite the pickle. If you could do anything on this green earth, what would it be?[/QUOTE] Well, keeping it realistic, probably working in defence (BAE, Bofors, Lockheed Martin, Rheinmetall you name it, mostly tanks, jets and that stuff rather than rifles) since that is the one thing I'm really interested in. Any decently high-tech industry would do, I like heavy machinery, mechanics and such. Problem is, I like almost all aspects of engineering/physics, so there is something I prefer, but it's not a massive difference. Management positions wouldn't be bad either, was close to taking industrial economy and administration instead of engineering in fact.
[QUOTE=Falubii;39516224]I don't see how a particle could have to do with time being passed. Is there a particle for each of our 3 spatial dimensions?[/QUOTE] No, and from that viewpoint, there wouldn't be a particle for time either - if you consider it to be a 4th dimension. However you can also consider time as a force (or energy), strongly related to gravity. It's quite likely that Einstein was right about time being a dimension, a property of space itself, but if it's not then there might as well be some sort of particle related to it. Gravity is universal, it's everywhere, just like time. Just as the Higgs bosons form a Higgs field, spreading out through the entire universe, giving all objects mass, there might be chroniton particles forming a field that would be universal and closely associated with (or even responsible for) the passage of time.
[QUOTE=JohanGS;39521077]This might help you (It's from a handbook published in 2011, so it's most likely up-to-date). [url]http://f2.braxupload.se/1a8hfc.dsc00597.jpg[/url][/QUOTE] Now the only problem is that I am from Finland, doesn't that mean that it's Finland who would take care of my Student benefits? [editline]9th February 2013[/editline] [QUOTE=acds;39522163]Well, keeping it realistic, probably working in defence (BAE, Bofors, Lockheed Martin, Rheinmetall you name it, mostly tanks, jets and that stuff rather than rifles) since that is the one thing I'm really interested in. [B]Any decently high-tech industry would do[/B], I like heavy machinery, mechanics and such. Problem is, I like almost all aspects of engineering/physics, so there is something I prefer, but it's not a massive difference. Management positions wouldn't be bad either, was close to taking industrial economy and administration instead of engineering in fact.[/QUOTE] What about space?
[QUOTE=booster;39523047]Now the only problem is that I am from Finland, doesn't that mean that it's Finland who would take care of my Student benefits?[/QUOTE] Hmm, there has to be some loophole somewhere. Are you planning to stay here for a long time? How long does it take to get a citizenship? I suggest you mail CSN or some authority/school, try to dig out as much as you can.
I was playing through Portal 2 just now and I found this. [img_thumb]http://i47.tinypic.com/bdpie8.jpg[/img_thumb] It's probably old, but it made me smile.
Not strictly related to physics, but how does one animate a plot in MATLAB? I've found a few scattered references to a getframe function, but I'm not sure how to transfer that to a plot. Specifically, I'm trying to animate a plot of the square modulus of a particular wave function (say the free particle's) against x with time, i.e. show how it changes with time. For completeness' sake, the function in question's below, but I'd be fine (and indeed probably better off) with just a point in the right direction rather than being told exactly what to do. [IMG]http://i.imgur.com/CTm182a.png[/IMG]
[QUOTE=JohnnyMo1;39518764]Yeah, I'm confused what there is to fix about them.[/QUOTE] I'll hopefully get the paper next week, since I don't do physics so don't fully understand what we were presented with.
[QUOTE=Greenandred;39528045]Not strictly related to physics, but how does one animate a plot in MATLAB? I've found a few scattered references to a getframe function, but I'm not sure how to transfer that to a plot. Specifically, I'm trying to animate a plot of the square modulus of a particular wave function (say the free particle's) against x with time, i.e. show how it changes with time. For completeness' sake, the function in question's below, but I'd be fine (and indeed probably better off) with just a point in the right direction rather than being told exactly what to do. [IMG]http://i.imgur.com/CTm182a.png[/IMG][/QUOTE] you're on the right track - you probably want to read the documentation on the [url=http://www.mathworks.co.uk/help/matlab/ref/movie.html]movie[/url] function, and associated frame functions
I took up an interest in fluid dynamics and was wondering why in a convergent nozzle, the maximum gas velocity is Mach 1 (assuming choke), but in a convergent-divergent (De Laval) nozzle, the expansion speeds up the gas to >Mach1. How does expanding something accelerate it?
I read that PET scans read the gamma ray signatures from the decay of antimatter from the radioisotopes they inject you with. That's pretty cool, who knew antimatter could save your life. [i]Positron Emission Tomography[/i]
Is it possible to find the velocity of an object if you are only given mass, distance, and v-initial? The object is not falling so I assume acceleration=/=9.81. But then what do I use?
[QUOTE=Sharker;39543128]Is it possible to find the velocity of an object if you are only given mass, distance, and v-initial? The object is not falling so I assume acceleration=/=9.81. But then what do I use?[/QUOTE] Distance from what?
Velocity is a vector so I assume the question is fairly easy but I am on my phone, so someone else please write the two formulas.
[QUOTE=Yahnich;39543874]depends, is it being thrown upwards or sidways, is v0 = 0 and is it just falling down????[/QUOTE] It's a cart rolling on a flat table. And the distance is just how far it moved from it's original point if that's what you're asking. I'm pretty sure the formula is vf^2 - vi^2 = 2ad, so that'd give me vf^2 - 0m/s = 2a(.83m). I just don't get what "a" would be.
[QUOTE=Sharker;39543128]Is it possible to find the velocity of an object if you are only given mass, distance, and v-initial? The object is not falling so I assume acceleration=/=9.81. But then what do I use?[/QUOTE] in what direction is the moving? if it's upwards you can just use v^2=u^2+2as where a -9.81. if it's being thrown sideways you can find the horizontal component by using v=d/t. I don't know how mass comes into play unless there's some more advanced mechanics that I don't know which uses it. [editline]11th February 2013[/editline] [QUOTE=Sharker;39545052]It's a cart rolling on a flat table. And the distance is just how far it moved from it's original point if that's what you're asking. I'm pretty sure the formula is vf^2 - vi^2 = 2ad, so that'd give me vf^2 - 0m/s = 2a(.83m). I just don't get what "a" would be.[/QUOTE] if the cart is just rolling along the flat table after being pushed and there's no friction then a=0 so unless they specify that there is a force acting on it then it's speed will remain the same.
Sounds like it's just a particle moving in 1-dimension with no acceleration. [editline]10th February 2013[/editline] I got [I]The Large Scale Structure of Space-Time[/I] by Hawking and Ellis from the library. It's actually really fantastic. Quite rigorous, but also really good explanation of what concepts mean intuitively. [editline]10th February 2013[/editline] Had no idea this girl was studying physics [media]http://www.youtube.com/watch?v=_nSFG5otT3g[/media]
[QUOTE=Yahnich;39545544]if it's a flat table velocity will never change unless you're given the friction component and then you'll have to solve a differential equation and figure out the forces and stuff[/QUOTE] Do you really need a differential equation? Couldn't you just use a coefficient of friction?
yeah I don't see why a differential equation needs to be involved, we did problems like that back in high school physics and mine wasn't even calc-based.
The face of people at parties when you tell them you study physics....
[QUOTE=booster;39523047] What about space?[/QUOTE] Pretty cool, but I don't know, don't feel as "attracted" to satellites and shuttles as I do to say, a Mercedes or a jet fighter. [QUOTE=Killuah;39547424]The face of people at parties when you tell them you study physics....[/QUOTE] I know that all too well. Usually it's followed by some question like "So can you build a car?" or "How much do they pay afterwards?". It does impress the girls though (as long as you aren't the stereotype engineer that has the social skills of a piston, in that case it's just gonna make you look even more of a stereotype).
[QUOTE=acds;39547873]Pretty cool, but I don't know, don't feel as "attracted" to satellites and shuttles as I do to say, a Mercedes or a jet fighter. [/QUOTE] Well one thing is for sure, there is a lot of money in the military business. And I'm not sure if this is applied in today's world, but in "Cosmos" Sagan stated that a huge bunch of graduated engineers get drafted by the military, so there is probably work in that field aswell.
[QUOTE=booster;39547896]Well one thing is for sure, there is a lot of money in the military business. And I'm not sure if this is applied in today's world, but in "Cosmos" Sagan stated that a huge bunch of graduated engineers get drafted by the military, so there is probably work in that field aswell.[/QUOTE] Military, petroleum, cars (mid to high class at least), and good contracts are all very well paying industries. Know a guy who works as engineer recruiter, he had found some engineers for some rich guy from the Middle East that needed a yacht built, at work done they got paid a "hefty sum" (he didn't specify, but apparently was more than most earn in a year) on top of the paychecks. Also yeah here in Sweden there is plenty of weapon manufacturing. Didn't stay neutral in the world wars by trading flowers with the big powers that's for sure. [editline]11th February 2013[/editline] I don't think anything can be better, for an engineer, than getting hired by a Saudi that needs his extremely expensive shit built and doesn't care for what he calls "pocket change".
[QUOTE=acds;39547951]Military, petroleum, cars (mid to high class at least), and good contracts are all very well paying industries. Know a guy who works as engineer recruiter, he had found some engineers for some rich guy from the Middle East that needed a yacht built, at work done they got paid a "hefty sum" (he didn't specify, but apparently was more than most earn in a year) on top of the paychecks. Also yeah here in Sweden there is plenty of weapon manufacturing. Didn't stay neutral in the world wars by trading flowers with the big powers that's for sure. [editline]11th February 2013[/editline] I don't think anything can be better, for an engineer, than getting hired by a Saudi that needs his extremely expensive shit built and doesn't care for what he calls "pocket change".[/QUOTE] damn if only computer scientists were valued this much
[QUOTE=Goodthief;39548071]damn if only computer scientists were valued this much[/QUOTE] Different markets. Plenty of ways for a CS to make money outside of normal employment, but not by being hired by Saudis. I assume CS has plenty of programming, which has a pretty big money making potential for relatively low effort (app market, many apps make a tonne of money while needing a relatively low amount of effort, Angry Birds being a great example).
I think my elementary particle physics prof likes to give me 9/20 on every exam (second time this happened now) :(
I just aced a math exam I failed twice with a 2.
[QUOTE=acds;39548150]Different markets. Plenty of ways for a CS to make money outside of normal employment, but not by being hired by Saudis. I assume CS has plenty of programming, which has a pretty big money making potential for relatively low effort (app market, many apps make a tonne of money while needing a relatively low amount of effort, Angry Birds being a great example).[/QUOTE] yeah my only fear is having my work lost in a sea of programs, It's going to be hard to be innovative in the future unless some new tech come into play. before that though I have to pass my physics exam, would anyone care to help me with part ii) of question 2 [url]http://www.freeexampapers.com/index.php/directory/download?location=A%20Level/Physics/CIE/2006%20Jun/9702_s06_qp_4.pdf[/url] What I did was I calculated the number of moles in the canister, and the number of moles in a full balloon and divided one by the other to find out how many balloons I could fill, apparently that's wrong. Anyone care to explain?
[QUOTE=Goodthief;39548696]yeah my only fear is having my work lost in a sea of programs, It's going to be hard to be innovative in the future unless some new tech come into play. before that though I have to pass my physics exam, would anyone care to help me with part ii) of question 2 [url]http://www.freeexampapers.com/index.php/directory/download?location=A%20Level/Physics/CIE/2006%20Jun/9702_s06_qp_4.pdf[/url] What I did was I calculated the number of moles in the canister, and the number of moles in a full balloon and divided one by the other to find out how many balloons I could fill, apparently that's wrong. Anyone care to explain?[/QUOTE] 1 mol in the canister fills much much less volume than 1 mol in the balloons(lower pressure->expansion). You need to calculate the volume of the gas in the cylinder if it had the pressure of the balloon and divide that volume by the volume of 1 balloon. [editline]11th February 2013[/editline] Tip: Calculate constant_cylinder for the given numbers. If you let that gas "out" into balloons, the constant stays the same, the pressure changes(but is given) and you can calculate the new volume. No need for mols here :D
[QUOTE=Killuah;39548748]1 mol in the canister fills much much less volume than 1 mol in the balloons(lower pressure->expansion). You need to calculate the volume of the gas in the cylinder if it had the pressure of the balloon and divide that volume by the volume of 1 balloon.[/QUOTE] oh right I see, thanks for the help [editline]11th February 2013[/editline] [QUOTE=Killuah;39548748] [editline]11th February 2013[/editline] Tip: Calculate constant_cylinder for the given numbers. If you let that gas "out" into balloons, the constant stays the same, the pressure changes(but is given) and you can calculate the new volume. No need for mols here :D[/QUOTE] that's pretty brilliant, I hate using mols
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