Physics Questions / Tips

capslocked

How might you find an APPROXIMATE value of the focal lenght? (focal lenght of concave mirror mock question)

Also does anyone think it likely that all three experiments -
Concave Mirror
A proportional to F
Specific Heat Capacity
- could be asked - none of them have come up so far

Tips: Wheatstone bridge, doppler effect, simple harmonic motion, optical fibres

mp3guy

capslocked wrote:

How might you find an APPROXIMATE value of the focal lenght? (focal lenght of concave mirror mock question)

Page 21 of your physics book...

sternn

Would you say there is a slim chance of the stuff that came up last year in full questions comming up this year?
So I could probably get away with having a vague knowledge of what came up last year??

mp3guy

sternn wrote:

Would you say there is a slim chance of the stuff that came up last year in full questions comming up this year?
So I could probably get away with having a vague knowledge of what came up last year??

Maybe, sometimes questions come up two years in a row. You could learn most of it over the weekend. Got back through the last 5 years and check the pattern.

carlowboy

sternn wrote:

Would you say there is a slim chance of the stuff that came up last year in full questions comming up this year?
So I could probably get away with having a vague knowledge of what came up last year??

Its very doubtful, there's too much stuff that could come up in long questions that hasn't been asked yet.

sternn

sternn wrote:

Would you say there is a slim chance of the stuff that came up last year in full questions comming up this year?
So I could probably get away with having a vague knowledge of what came up last year??

Sorry, what i mean to say is: Could i almost completely ignore the stuff that came up last year and know everything else?

JC 2K3

Judging by Irish 2, English 2 and History - no.

madgal

I would go by what came up in the pre.

So far paper 2 of Irish covered most of what came up in the pre, and so did the french paper as well.

carlowboy

Sternn- I really doubt it. There's some stuff they love asking every year. (short questions and modern physics)

madgal

Chapter 29 --- Xrays! I spent 3 hours learning that in evening study one night ... and it comes up every year ... its like a definite question!

carlowboy

madgal wrote:

Chapter 29 --- Xrays! I spent 3 hours learning that in evening study one night ... and it comes up every year ... its like a definite question!

Aye, love the X-Rays myself. There's not much in it, so its a simple enough question. If you know your diagram for the production of X-Rays you're set and medical and industrial applications.

Turnip2000

Theres so much choice in physics but the biggest problem i find is that the stuff you know comes up in questions with the stuff you don't know!!:mad:

Its all about choosing the right Q's, And ye i think they repeat theme selfs alot! Well i hope they do anyway!

madgal

I just don't understand Einsteins part of the thing ... why was the guy such a genius ... and why was I such a dumbass?!?

Nehpets

I know what you mean TurnipFace!

Nehpets

madgal wrote:

I just don't understand Einsteins part of the thing ... why was the guy such a genius ... and why was I such a dumbass?!?

What part? (not that I'll be able to answer, but I'm sure someone else might be able to )

Limerick Dude

Nehpets wrote:

What part? (not that I'll be able to answer, but I'm sure someone else might be able to )

e=mc squared......

energy = mass by the speed of light squared....

Pretty easy equation

Nehpets

Limerick Dude wrote:

e=mc squared......

energy = mass by the speed of light squared....

Pretty easy equation

Who asked for that?

Turnip2000

Mass as in the change in mass after the ....watever it is!

RandolphEsq

I left out the Sound and Vibrations chapter as well as The Wave Nature of Light. The last few chapters in the book are what Im hoping come up a good bit; all that nuclear stuff and particle physics

JC 2K3

I want as much mechanics as possible(1.5 Qs?).

Questions on Heat are also easy and nice.

Particle physics should be 56/56, have to go over it though.

I'd like a full question on EMI also, it looks hard but it's so easy after you just learn it.

carlowboy

Anyone get the feeling there'll be something big on semi-conducters? I've only ever seen them come up in Q12 and that was once.

WildCardDoW

It's quite hard to tell what will come up. Just learn it all!

ON another note, does anyone happen to have a list of the questions that have come up previsouly. I.E Pressure was part of Q12. etc.

I was sure I had a lost like this, but I'll be danged if I can't find it! When I need it most of course, it's got lost in a mess of notes.

Maybe this was it, nevermind: http://www.skoool.ie/skoool/examcentre_sc.asp?id=2107

My teacher never gave us any of this stuff, I always had to use teh internets.

Limerick Dude

JC 2K3 wrote:

I want as much mechanics as possible(1.5 Qs?).

Questions on Heat are also easy and nice.

Particle physics should be 56/56, have to go over it though.

I'd like a full question on EMI also, it looks hard but it's so easy after you just learn it.

Whats EMI again? Sometimes the mechanics q6 can be dodgy, like angular velocity, dont like that. Though i find it very easy to derive kepplers law

WildCardDoW

Hate angular velocity, I can define it, just always muck up the questions to work them out.

carlowboy

Limerick Dude wrote:

Whats EMI again? Sometimes the mechanics q6 can be dodgy, like angular velocity, dont like that. Though i find it very easy to derive kepplers law

Electromagnetic Induction.

Cipriana

ye I'd bet on semi conductors and a latent heat one normally comes up

cocoa

Limerick Dude wrote:

Whats EMI again? Sometimes the mechanics q6 can be dodgy, like angular velocity, dont like that. Though i find it very easy to derive kepplers law

umm, do you mean kepler's law (one p)? and that's not on the course...

microbiek

cocoa wrote:

umm, do you mean kepler's law (one p)? and that's not on the course...

T^2 is proportional to R^3

Feddd

When the exam is being made out, the short questions are done last (Q5). They are the things that "Didn't get a go" that year and are likley to come up the next year in long Qs. Static elec and doppler are looking good for Longs this year.
personally, 3 mechanics exps and 5 mechanics long Qs would be sweet. Applies maths ftw!

microbiek

Feddd wrote:

When the exam is being made out, the short questions are done last (Q5). They are the things that "Didn't get a go" that year and are likley to come up the next year in long Qs. Static elec and doppler are looking good for Longs this year.
personally, 3 mechanics exps and 5 mechanics long Qs would be sweet. Applies maths ftw!

that would hardly happen

Fobia

cocoa wrote:

umm, do you mean kepler's law (one p)? and that's not on the course...

He seems to be correct, actually...

Leaving Cert Physics Syllabus

How odd.

cocoa

microbiek wrote:

T^2 is proportional to R^3

O_o, calling it "kepler's law" is a bit of stretch, considering there was three laws, and they referred to eliptical orbits, not just circular ones, and you derive a formula, not just that proportion, and nowhere in the syllabus do they call it kepler's law...

microbiek

cocoa wrote:

O_o, calling it "kepler's law" is a bit of stretch, considering there was three laws, and they referred to eliptical orbits, not just circular ones, and you derive a formula, not just that proportion, and nowhere in the syllabus do they call it kepler's law...

ive seen it they do call it that and its sumtin lik T^2=GMm/R^3(4pi^2) is the formula nt sure!!

cocoa

microbiek wrote:

ive seen it they do call it that and its sumtin lik T^2=GMm/R^3(4pi^2) is the formula nt sure!!

have a look at fobia's link to the syllabus, nowhere is the word "kepler" in it. You haven't got the formula right, but I think you're thinking of the right thing. Kepler's third law mentions the proportion between T^2 and R^3, not the formula...

Nehpets

Feddd wrote:

When the exam is being made out, the short questions are done last (Q5). They are the things that "Didn't get a go" that year and are likley to come up the next year in long Qs.

Where did you get that info?

carlowboy

That's not one of Kepler's laws though. What exactly is it called?

cocoa

carlowboy wrote:

That's not one of Kepler's laws though. What exactly is it called?

it is, technically, a very special case of the third law. It's not given a special name in the syllabus, I don't know if it has one, I've always just called it "formula for the period of a satelite (in a circular orbit)"

microbiek

cocoa wrote:

have a look at fobia's link to the syllabus, nowhere is the word "kepler" in it. You haven't got the formula right, but I think you're thinking of the right thing. Kepler's third law mentions the proportion between T^2 and R^3, not the formula...

oh ryt yeah its T62=4pi62R^3/GM you derive it by saying newtons grav equals centripetal force ye its just pat doyle goin into extar detils just sayin that it states t^2 is prop to R^3

microbiek

motion of a satellite: The moon is a satellite of the earth Keplers 3rd law states that the periodic time squared is proportional to the radius cubed

Tomlowe

it's keplers third law and its derivation has come up before.

microbiek

Tomlowe wrote:

it's keplers third law and its derivation has come up before.

came up in the mocks

carlowboy

Tomlowe wrote:

it's keplers third law and its derivation has come up before.

They didn't word it as Kepler's law in the question though did they?

cocoa

Tomlowe wrote:

it's keplers third law and its derivation has come up before.

no, it's a formula which happens to be very special case of kepler's third law. You don't have to know the law, or have any extra knowledge about the proportion which happens to be contained in the formula.

microbiek

where can you get all the syllabuses paticularly the engineering one???

microbiek

cocoa wrote:

no, it's a formula which happens to be very special case of kepler's third law. You don't have to know the law, or have any extra knowledge about the proportion which happens to be contained in the formula.

it just works out that way when you let w=2pi/T

carlowboy

cocoa wrote:

no, it's a formula which happens to be very special case of kepler's third law. You don't have to know the law, or have any extra knowledge about the proportion which happens to be contained in the formula.

Well its not a very special case. It deals with circular orbits not eliptical ones (which Kepler's 3rd law was about). But most planet's orbit and satellites orbit are very close to circular so it is reasonably argument. Its not relevant at all in comets though.

You're right though.

cocoa

there's no w in that formula, you don't have to study the link between simple harmonic motion and circular motion. There's no "working out" necessary, the formula is an equation, as it happens everything other than R and T are constant, so they are proportional, simple, but totally unnecessary for the LC course.

syllabuses

microbiek

cocoa wrote:

there's no w in that formula, you don't have to study the link between simple harmonic motion and circular motion.

syllabuses

ther is at the start as centripetal f = mw^2R its not w its a greek letter........thanks for the syllabuses

cocoa

microbiek wrote:

ther is at the start as centripetal f = mw^2R its not w its a greek letter........thanks for the syllabuses

oh, you mean omega, angular velocity. It's still not in the formula for the period of a satelite, you mean the derivation? I suppose if you do let omega equal that then it works out that R^3 and T^2 are equal, but that's really beside the point...

JC 2K3

cocoa wrote:

there's no w in that formula, you don't have to study the link between simple harmonic motion and circular motion. There's no "working out" necessary, the formula is an equation, as it happens everything other than R and T are constant, so they are proportional, simple, but totally unnecessary for the LC course.

syllabuses

syllabi.

carlowboy

JC 2K3 wrote:

syllabi.

Thought I'd come across as a pedantic git if I said that