Post by: falafail on November 14, 2009, 02:43:25 pm
so if you're doing past papers or whatever, post the tricky questions here.
and if you're revising, post about stuff you think is important, or stuff you don't get here.
etcetc
maybe we can help each other get awesome grades ;D
Post by: Tumble Bug on November 14, 2009, 03:17:07 pm
the ans 108cm
Post by: falafail on November 14, 2009, 03:25:40 pm
please check june 2002 paper 2 ques no 3 b (iii) how will v solve this...i suppposed x from the pivot ...but... nuthing
the ans 108cm
okay, let's assume the distance from x to the center of gravity is d.
so 950d = (570 x 0.4) + (380 x 2.1) <-- you use 950 because it's the weight, so it acts on the center of gravity. and 2.1 because it's 2.5 - 0.4
then you just solve for d.
the answer is 1.08 m.
Post by: Tumble Bug on November 14, 2009, 03:31:37 pm
okay, let's assume the distance from x to the center of gravity is d.
so 950d = (570 x 0.4) + (380 x 2.1) <-- you use 950 because it's the weight, so it acts on the center of gravity. and 2.1 because it's 2.5 - 0.4
then you just solve for d.
the answer is 1.08 m.
*gasp* OMG i really AM a blonde!! :o :P
thanks a bunch!! :)
Post by: falafail on November 14, 2009, 03:32:46 pm
*gasp* OMG i really AM a blonde!! :o :P
thanks a bunch!! :)
s'okay, i cheated :P hahaha
Post by: Tyserius on November 14, 2009, 05:53:19 pm
Post by: wannapass on November 14, 2009, 06:14:02 pm
Post by: falafail on November 15, 2009, 12:57:40 pm
get your past papers out, haha
june 05 question 6 (b) (ii)
nov 04 question 6 (b) (i)
nov 03 question 4 (a) how are you supposed to find the frequency from the graph(s)? :-\ and, same question, part (b) (iii) wtf
nov 03 question 5 (a) (i) how do you know which one's the positive plate and which one's the negative? also, same question part (b) (ii)
phew.
Post by: saadiyah on November 15, 2009, 01:05:47 pm
A point source of sound radiates energy uniformly in all directions. At a distance of 3.0 m from source, the amplitude of vibration of air molecules is 1.0 X 10-7 m. Assuming that no sound energy is absorbed, calculate the amplitude of vibration at a distance of 5 m from source.
Answer is 6.0 x 10-8 m.
Post by: falafail on November 15, 2009, 01:18:12 pm
plz can u help me with this question?
A point source of sound radiates energy uniformly in all directions. At a distance of 3.0 m from source, the amplitude of vibration of air molecules is 1.0 X 10-7 m. Assuming that no sound energy is absorbed, calculate the amplitude of vibration at a distance of 5 m from source.
Answer is 6.0 x 10-8 m.
what paper is this from?
Post by: Tumble Bug on November 15, 2009, 01:42:25 pm
okay this ques...the plates..ur suppoused to look at the terminals of the battery...from there u knw k which is =ve and -ve...
and part bii...the energy u find in part b i is equal to the kinetic energy...make V the subject.... and u get 1.25*10 raise to power 7
m checking the other ques...i'll lrt u knw ..By the way..what does it mean wen they say k an ammetere or voltmeter has infinite resistance??
Post by: Tumble Bug on November 15, 2009, 01:48:13 pm
okay ur supposed to look at the time period from the graph and divide that by i as f = 1/tu get frequency....
part b m nt really sure about this but i saw in one of the past papers that when frequency is halfed...wavelrnght is doubled..nt sure...cnfrim this okay..
Post by: Tumble Bug on November 15, 2009, 01:54:19 pm
this question ur supposed to take out the perpendicular distance from the source...use sin thete = p/h u get sin 35* 2.5*10^-3 which is equal to 1.43*10^-3...multiply by force u get torque an d the oct 04 question..i dont knw that one :S
Post by: Tumble Bug on November 15, 2009, 02:24:30 pm
how are we suppouse to find area under tha graph????
???
Post by: saadiyah on November 15, 2009, 02:31:23 pm
what paper is this from?I guess it's paper 2. the question is from nov 85 paper.it's very old.
Post by: falafail on November 15, 2009, 02:32:35 pm
oct 2005 Q4 (a) (ii)
how are we suppouse to find area under tha graph????
???
i found the area of one big square then estimated the number of squares under the graph and multiplied it by the area that i got lol
thanks for answering my questions By the way, i'll check them out when i'm done with the paper i'm doing ;D
Post by: Tumble Bug on November 15, 2009, 02:33:46 pm
thanx...
Post by: Tumble Bug on November 15, 2009, 02:34:51 pm
i found the area of one big square then estimated the number of squares under the graph and multiplied it by the area that i got lol
thanks for answering my questions By the way, i'll check them out when i'm done with the paper i'm doing ;D
Np... :D
Post by: khi2ruh on November 15, 2009, 03:09:57 pm
oh and Q5 part c (i)and(ii) of the same paper...
thanx...
U have to use the relationship I is proportional to A^2
I is proportional to (3*10^-4)^2
take x as the intensity of wave B so then x is proportional to (2*10^-4)^2
((2*10^-4)^2)I=((3*10^-4)^2)(x)
solve the equation
x= 4/9 I
Post by: Tumble Bug on November 15, 2009, 03:13:36 pm
Post by: Tyserius on November 15, 2009, 03:26:00 pm
Post by: falafail on November 15, 2009, 03:27:51 pm
I hate questions where they ask you to explain what will happen when the scenario changes... Must make sure it is with reference to the equations, logic and physics principles. So annoying!agh, yeah. i don't like written questions, i'd rather calculate thingssssssss
By the way, can you check out the questions i posted on the first page? tumble bug did a few but she/he didn't know about some of them D:
Post by: Tumble Bug on November 15, 2009, 03:31:47 pm
agh, yeah. i don't like written questions, i'd rather calculate thingssssssss
By the way, can you check out the questions i posted on the first page? tumble bug did a few but she/he didn't know about some of them D:
lol...im a SHE...hheheh...
Post by: MaNi_DaDuDe on November 15, 2009, 03:32:16 pm
plz can u help me with this question?
A point source of sound radiates energy uniformly in all directions. At a distance of 3.0 m from source, the amplitude of vibration of air molecules is 1.0 X 10-7 m. Assuming that no sound energy is absorbed, calculate the amplitude of vibration at a distance of 5 m from source.
Answer is 6.0 x 10-8 m.
Cross multiply. :]
Post by: Tyserius on November 15, 2009, 04:36:17 pm
plz can u help me with this question?
A point source of sound radiates energy uniformly in all directions. At a distance of 3.0 m from source, the amplitude of vibration of air molecules is 1.0 X 10-7 m. Assuming that no sound energy is absorbed, calculate the amplitude of vibration at a distance of 5 m from source.
Answer is 6.0 x 10-8 m.
As I = ka2 and is directly proportional to 1/r2,
ka2 = m/r2 (m is the other constant)
And since r is increased from 3.0m to 5.0m the new r, r' is = 5/3 r
So to find your new amplitude, a' :
ka'2 = m/(5/3 r)2
ka'2 = m/(25/9 r2)
ka'2 = 9/25 m/r2
ka'2 = 9/25 (ka2) << Substitute from ka2 = m/r2
a' = 3/5 a
= 3/5 (1.0 x 10-7)
= 6.0 x 10-8m
Post by: falafail on November 15, 2009, 05:35:20 pm
QUESTIONSQUESTIONSQUESTIONS
get your past papers out, haha
june 05 question 6 (b) (ii)
nov 04 question 6 (b) (i)
nov 03 question 4 (a) how are you supposed to find the frequency from the graph(s)? :-\ and, same question, part (b) (iii) wtf
nov 03 question 5 (a) (i) how do you know which one's the positive plate and which one's the negative? also, same question part (b) (ii)
phew.
tell me how to solve theeeeeeeese D:
also, june 03 question 4 (i) 1, and (iii)
what affects the seperation/brightness of fringes and stuff? i never actually got that .__.
Nov 02 5b (iii),
june 02 4b(ii),
nov 01 6- all of it.
plzplzplzplzpzlpzlpz tell me how to do these? anyone? :(
Post by: saadiyah on November 15, 2009, 05:55:10 pm
As I = ka2 and is directly proportional to 1/r2,thx a lot!^^
ka2 = m/r2 (m is the other constant)
And since r is increased from 3.0m to 5.0m the new r, r' is = 5/3 r
So to find your new amplitude, a' :
ka'2 = m/(5/3 r)2
ka'2 = m/(25/9 r2)
ka'2 = 9/25 m/r2
ka'2 = 9/25 (ka2) << Substitute from ka2 = m/r2
a' = 3/5 a
= 3/5 (1.0 x 10-7)
= 6.0 x 10-8m
Post by: happy angel on November 15, 2009, 05:57:05 pm
tell me how to solve theeeeeeeese D:
also, june 03 question 4 (i) 1, and (iii)
what affects the seperation/brightness of fringes and stuff? i never actually got that .__.
Nov 02 5b (iii),
june 02 4b(ii),
nov 01 6- all of it.
plzplzplzplzpzlpzlpz tell me how to do these? anyone? :(
j03: a(i) the sources must have same frequency and wavelength and phase difference btwn the sources mustbe constant or zero..
and 4 (iii) u nid wich part? 1 2 or 3?
Post by: saadiyah on November 15, 2009, 06:09:32 pm
It is possible to use two separate oscillators feeding 2 loudspeakers to demonstrate interference of sound. It is not possible to use 2 filament lamps, however similar, to produce interference of light. explain this difference.
Post by: falafail on November 15, 2009, 06:13:05 pm
j03: a(i) the sources must have same frequency and wavelength and phase difference btwn the sources mustbe constant or zero..oh sorry, i meant 4 (b) (i) 1 not 4 (a) D:
and 4 (iii) u nid wich part? 1 2 or 3?
and um, all of it. i need someone to explain what affects separation/brightness of fringes etc
Post by: happy angel on November 15, 2009, 06:21:40 pm
plzz help me with this one..
It is possible to use two separate oscillators feeding 2 loudspeakers to demonstrate interference of sound. It is not possible to use 2 filament lamps, however similar, to produce interference of light. explain this difference.
am not sure but abt the filaments la i fink its bcoz for interference to occur the sources must b monochromatic ie sme freq n wavelength wiv phase diff etc as i xplained above..
for the sound maybe the oscillators may be made to vibrate at the same freq so that interence occurs and the loudspeakers act as slits with d being the distance btwn the slits.. it will give the intensity of sound after interference ie soft or loud..wich rep the dark n bright fringes respectively..
i hope u und ;D :-[ ::) ??? 8)
Post by: happy angel on November 15, 2009, 06:31:03 pm
oh sorry, i meant 4 (b) (i) 1 not 4 (a) D:
and um, all of it. i need someone to explain what affects separation/brightness of fringes etc
ah sory,, it must be comparable to wavelength.. so smfing relatively small eg 1mm
abt separation of fringes use the eqn B=(D times lamda)/d
were D is distance btwn double slit arrangement and screen
d is separation of the 2 slits..
varying D and d ul see abt separation.
now intensity.
use I = k/r2
were r is the distance btwn 1st slit and the double slit..
wen r decreases I ie intensity increases.
ermm i managed to mk u und? a bit? ???
Post by: saadiyah on November 15, 2009, 06:45:23 pm
am not sure but abt the filaments la i fink its bcoz for interference to occur the sources must b monochromatic ie sme freq n wavelength wiv phase diff etc as i xplained above..
for the sound maybe the oscillators may be made to vibrate at the same freq so that interence occurs and the loudspeakers act as slits with d being the distance btwn the slits.. it will give the intensity of sound after interference ie soft or loud..wich rep the dark n bright fringes respectively..
i hope u und ;D :-[ ::) ??? 8)
thx happy angel..i think i get it :D
Post by: happy angel on November 15, 2009, 06:49:43 pm
thx happy angel..i think i get it :D
welcome dr... n thx u too 4 mking me revise.. hehe ;D
Post by: happy angel on November 15, 2009, 06:55:25 pm
welcome dr... n thx u too 4 mking me revise.. hehe ;D
hey tell me in june 09 p2 the 1st ans wen u calculate error its 0.18.
in marking scheme its 0.09
y shud we divide by 2??
plzz tl meee :'( :-[
Post by: Asif iqbal on November 15, 2009, 08:54:13 pm
Post by: MaNi_DaDuDe on November 15, 2009, 08:59:48 pm
Guys I've got this really cool list of all the definations really good for final revision will hardly take ten minutes to read all of them where do I post them here or should I make a new topic for it??
Hey :)
Just attach it here, thanks! :D
Post by: falafail on November 16, 2009, 04:07:38 am
ah sory,, it must be comparable to wavelength.. so smfing relatively small eg 1mmWait so in that first equation whats B?
abt separation of fringes use the eqn B=(D times lamda)/d
were D is distance btwn double slit arrangement and screen
d is separation of the 2 slits..
varying D and d ul see abt separation.
now intensity.
use I = k/r2
were r is the distance btwn 1st slit and the double slit..
wen r decreases I ie intensity increases.
ermm i managed to mk u und? a bit? ???
And the intensity is inversly proportonal to r2 then? Is that the only thing that a ffects the intensity?
Post by: falafail on November 16, 2009, 04:10:06 am
hey tell me in june 09 p2 the 1st ans wen u calculate error its 0.18.
in marking scheme its 0.09
y shud we divide by 2??
plzz tl meee :'( :-[
I cant download the past paper right now but if you post the question i can probably help..
Post by: falafail on November 16, 2009, 08:02:30 am
Post by: Hwa1 on November 16, 2009, 08:04:43 am
was quite easy, only think i lost 5 marks
the spring question drove me nuts though..could get 0.077
wat did u guys get for phase difference?
also the wave thing...speed is..?
(im tryin not to expose too much lol)
Post by: falafail on November 16, 2009, 08:08:31 am
I lost like, 12-20 marks, at least :(
Post by: MaNi_DaDuDe on November 16, 2009, 08:32:24 am
I dont know, dont remember.
I lost like, 12-20 marks, at least :(
Dude. You are not alone. I lost like 18 marks for sure.
The paper was soooooooo easy. However, the time. omfg. I thought we had 1 hour 15 mins like the other p2s so I was taking it easy. I couldn't do the electricity OR the waves question (NO TIME LEFT)! :( I did radiation in the last 2 mins, easy sh*t.
bleh :(
Post by: Hwa1 on November 16, 2009, 08:35:20 am
waves question i think i lost 2-3 marks
spring question was the real problem..
and the 1st question i dno if my significant figures were correct or not for my answers =-S
Post by: josephwhite on November 16, 2009, 08:38:59 am
did not get the uncertainity question...so uncertain in my answer...then didnt get the 0.077 J spring.... good thing get 1 mark only..
CIE becomes scrooge mcduck in this paper...tighwad in givin marks... lol
Post by: MaNi_DaDuDe on November 16, 2009, 08:40:02 am
electricity was alryt, but there were a lot of calculations wich killed time
waves question i think i lost 2-3 marks
spring question was the real problem..
and the 1st question i dno if my significant figures were correct or not for my answers =-S
I just did em all in 2 dp.
I just wish I was quicker.. :(
Same thing happened to me in p1, easy paper, no time to finish. :( :(
Post by: Dhalia on November 16, 2009, 08:43:47 am
Post by: Dhalia on November 16, 2009, 08:45:37 am
Post by: josephwhite on November 16, 2009, 08:46:30 am
Post by: MaNi_DaDuDe on November 16, 2009, 08:51:55 am
same here....just finished a half of p1...then a li'll bit dawdlin...then suddenly the invigilator said "5 minutes left"....then I rushed in...completed all the questions by eenie meenie minie moe..... man....
Yeah I rushed through 25-30. (in 2 mins)
When he was snatching the scantron, I scribbled in the last 10. *random* :'(
Post by: falafail on November 16, 2009, 09:04:11 am
Dude. You are not alone. I lost like 18 marks for sure.
The paper was soooooooo easy. However, the time. omfg. I thought we had 1 hour 15 mins like the other p2s so I was taking it easy. I couldn't do the electricity OR the waves question (NO TIME LEFT)! :( I did radiation in the last 2 mins, easy sh*t.
bleh :(
Wtf no :|
I wouldve done the same ven if we had more time. I didnt know how to do the velocity or spring questions :'(
Post by: MaNi_DaDuDe on November 16, 2009, 09:21:35 am
Wtf no :|
I wouldve done the same ven if we had more time. I didnt know how to do the velocity or spring questions :'(
How's that possible?
I swear I didn't even do past papers.
v2=u2+2as was the equation to use mostly.
Then it was the s=ut+1/2at2
then it was the wtfness of doing a vector diagram. I had to borrow a compass (which had no pencil By the way, so I scribbled some lines along the nib). :S I got 3.20 or something :/
Spring questions, yes. I did mess up there myself. I forgot what was the relationship between force and extension (wtf?) lol.
Hope the gt is down down down, dowwwwwwwwwwnnnn. lawl. :(
Post by: happy angel on November 16, 2009, 09:33:51 am
How's that possible?
I swear I didn't even do past papers.
v2=u2+2as was the equation to use mostly.
Then it was the s=ut+1/2at2
then it was the wtfness of doing a vector diagram. I had to borrow a compass (which had no pencil By the way, so I scribbled some lines along the nib). :S I got 3.20 or something :/
Spring questions, yes. I did mess up there myself. I forgot what was the relationship between force and extension (wtf?) lol.
Hope the gt is down down down, dowwwwwwwwwwnnnn. lawl. :(
hey i didnt gt thoz ques u discussing 4 xam physics p2 2d!
n p5 was horrible... the worst p5 iv wrked...
hw u found it??
Post by: yuedidi on November 16, 2009, 09:46:42 am
Post by: happy angel on November 16, 2009, 09:49:32 am
izzit important about the significant figure?... because i got quite a number of question which the number showing 2 significant but the answer got 3 significant or watever .... ==... if significant not correct we lost the accuracy marks?
u talking abt wich paper??
Post by: Dooraven on November 16, 2009, 09:50:15 am
Post by: yuedidi on November 16, 2009, 09:51:31 am
Post by: happy angel on November 16, 2009, 09:52:21 am
p2 v2 I think.
ah! we got 1st variant i fink...
hw u found p5??
Post by: MaNi_DaDuDe on November 16, 2009, 09:53:39 am
How was your paper?
Did you finish?
Post by: happy angel on November 16, 2009, 09:55:06 am
Yeah happy angel, you did variant 1.
How was your paper?
Did you finish?
yaa was pretty cul vry easy..
bt i lost 3 marks!! the waves ques...
pffff :'(
Post by: yuedidi on November 16, 2009, 09:55:47 am
can anyone answer me , izzit significant figure important in scoring thos accuracy marks
Post by: MaNi_DaDuDe on November 16, 2009, 09:58:11 am
Sucks the threshold is high. We do not get enough time. :(
Post by: Dooraven on November 16, 2009, 09:58:35 am
Post by: MaNi_DaDuDe on November 16, 2009, 09:59:40 am
I reckon 2 or 3 sf should be fine
Dunno bout sf's. ( I suck at math :D )
I made em all 2 dp
Post by: happy angel on November 16, 2009, 10:01:08 am
exam was very easy i think this year the grade threshold will be very high....it depends it can vary bt tell me hw u found p5? 1st ques
can anyone answer me , izzit significant figure important in scoring thos accuracy marks
Post by: falafail on November 16, 2009, 10:01:27 am
How's that possible?
I swear I didn't even do past papers.
v2=u2+2as was the equation to use mostly.
Then it was the s=ut+1/2at2
then it was the wtfness of doing a vector diagram. I had to borrow a compass (which had no pencil By the way, so I scribbled some lines along the nib). :S I got 3.20 or something :/
Spring questions, yes. I did mess up there myself. I forgot what was the relationship between force and extension (wtf?) lol.
Hope the gt is down down down, dowwwwwwwwwwnnnn. lawl. :(
Hah
Shaddap i tried that equation but i didnt get the answer so i just gave up :(
Post by: MaNi_DaDuDe on November 16, 2009, 10:02:59 am
Hah
Shaddap i tried that equation but i didnt get the answer so i just gave up :(
Wtf. How could you not get that? >:|
Soooooooo, crying club building ? :o
Post by: ilmarien on November 16, 2009, 10:43:28 am
I think I'll get worse than C... :-[
Post by: falafail on November 16, 2009, 10:54:59 am
Wtf. How could you not get that? >:|
Soooooooo, crying club building ? :o
Shuttuppppp idkkk :'(
S'okay, my friend hugged me :(
Also, im not completelyy bummed out as today was my last exam! IM DONEEE ;D
Post by: MaNi_DaDuDe on November 16, 2009, 11:12:47 am
Shuttuppppp idkkk :'(
S'okay, my friend hugged me :(
Also, im not completelyy bummed out as today was my last exam! IM DONEEE ;D
I have bio p2 tomorrow.
Join your penguin
Post by: Tyserius on November 16, 2009, 11:37:26 am
Post by: Tyserius on November 16, 2009, 11:54:12 am
Just did it
was quite easy, only think i lost 5 marks
the spring question drove me nuts though..could get 0.077
wat did u guys get for phase difference?
also the wave thing...speed is..?
(im tryin not to expose too much lol)
The phase difference is 1.5
The incident wave from the oscillator would travel along the string to the other end, P and would be reflected at the same frequency, amplitude and wavelength. The two waves would then experience superposition to form the stationary wave. The speed above is actually the speed of either the incident wave or the reflected wave.
And for your spring question. To get the energy it's actually done the following way :
k = 1.8 N cm-1 = 180 N m-1
First : The extension of the spring with the load is 2.1cm, so energy for the extension is 1/2 kx2 = 1/2 (180)(0.021)2 = EP1
Second : The extension of the spring after added with the force, F is 1.5cm + 2.1cm = 3.6cm, so energy for the extension is 1/2 (180)(0.015+0.021)2 = EP2
Use EP2 - EP1 to get the change in elastic potential energy :)
By the way, most of the values were 2 significant figures D:
Quote from: falafail
Wtf no :|
I wouldve done the same ven if we had more time. I didnt know how to do the velocity or spring questions
The velocity question was actually to just use your ruler to draw the lines D: And you can actually double check by using the following formula :
Let vR be the resultant velocity, vx be the horizontal velocity and vy be the vertical velocity.
vR = Square root of (vx2 + vy2)
Then the horizontal angle can be found by tan
The vertical angle then can be obtained by 90 -
Post by: Tyserius on November 16, 2009, 12:00:21 pm
exam was very easy i think this year the grade threshold will be very high....
can anyone answer me , izzit significant figure important in scoring thos accuracy marks
You have to have consistent significant figures. If not, your answers might not score you marks. So let's say your working is all correct but your answer is in wrong number of significant figures, you don't score the mark for Answer, A1. That's what I heard..
How's that possible?
I swear I didn't even do past papers.
v2=u2+2as was the equation to use mostly.
Then it was the s=ut+1/2at2
then it was the wtfness of doing a vector diagram. I had to borrow a compass (which had no pencil By the way, so I scribbled some lines along the nib). :S I got 3.20 or something :/
Spring questions, yes. I did mess up there myself. I forgot what was the relationship between force and extension (wtf?) lol.
Hope the gt is down down down, dowwwwwwwwwwnnnn. lawl. :(
How did you get 3.20? I got 7.4 m s-1. The angle I got was 33 I think. Can't remember much. But this paper was easier than past years... Just hope I do well >_< What a silly paper this time.. But the good thing is at least they balanced it out as P1 and P3 were rather difficult..
Post by: Tumble Bug on November 16, 2009, 12:15:14 pm
[/quote]
i got the same values!! :)...but the paper was okay..i was out of time..i missed the table with the resistors and every thing in that question after that!! >:( :( :'(
hope we all do well...InshALLAH!!! :)
Post by: ilmarien on November 16, 2009, 12:17:31 pm
How did you get 3.20? I got 7.4 m s-1. The angle I got was 33 I think. Can't remember much. But this paper was easier than past years... Just hope I do well >_< What a silly paper this time.. But the good thing is at least they balanced it out as P1 and P3 were rather difficult..WHAT?! How could you get 33 for the angle? ???
I got the 7.4 m/s, but when I calculated with sin (Theta) = 4/6.2, I got 40 degree for the angle.
Don't tell me I got the sin formula wrong...
OH MY GOD!!!! i JUST REALIZED IT'S WRONG!!!!! SHOULD'VE BEEN TAN THETA!!!!!!!
I AM SO DEPRESSED RIGHT NOW!! I'VE ALREADY LOST SO MANY MARKS BY NOT HAVING THE TIME TO DO SOME QUESTIONS!
Sorry for the Caps, I would like to ask forgiveness from all of you.
Post by: Tyserius on November 16, 2009, 12:33:23 pm
WHAT?! How could you get 33 for the angle? ???
I got the 7.4 m/s, but when I calculated with sin (Theta) = 4/6.2, I got 40 degree for the angle.
Don't tell me I got the sin formula wrong...
OH MY GOD!!!! i JUST REALIZED IT'S WRONG!!!!! SHOULD'VE BEEN TAN THETA!!!!!!!
I AM SO DEPRESSED RIGHT NOW!! I'VE ALREADY LOST SO MANY MARKS BY NOT HAVING THE TIME TO DO SOME QUESTIONS!
Sorry for the Caps, I would like to ask forgiveness from all of you.
Nah, it's alright about the caps :) What's done is done! Don't regret on the past. Study more when A2 begins then! :)
@Tumble Bug : OMG! The resistance table was the easiest and fastest to score...
Post by: Tumble Bug on November 16, 2009, 12:42:59 pm
@Tumble Bug : OMG! The resistance table was the easiest and fastest to score...
that makes me feel ALOT better!!!
i didnt have time...the woman was like 5 mins and i still had 3 questions to go!! :( :'(
Post by: Tyserius on November 16, 2009, 12:45:48 pm
that makes me feel ALOT better!!!
i didnt have time...the woman was like 5 mins and i still had 3 questions to go!! :( :'(
You should have skipped the questions that were taking more time first... But oh well, what's done is done! No use thinking back! Look on the bright side, another paper is done! :D
Post by: Tumble Bug on November 16, 2009, 12:48:41 pm
You should have skipped the questions that were taking more time first... But oh well, what's done is done! No use thinking back! Look on the bright side, another paper is done! :D
yea..InshALLAH all will go well..
2day was my last!! :) *dances*
Post by: Tyserius on November 16, 2009, 12:49:40 pm
yea..InshALLAH all will go well..
2day was my last!! :) *dances*
Hahaha! Same here! I already had my celebration :P
Post by: Q80BOY on November 16, 2009, 12:51:28 pm
u finished discussing the paper and are about to leave now :P
Post by: Tumble Bug on November 16, 2009, 12:53:34 pm
i think its too late to remind u guys that exam discussion only takes place 24 hours AFTER the exam!!
u finished discussing the paper and are about to leave now :P
loooooooollllllllll
my bad!! :P ;D
Post by: Tyserius on November 16, 2009, 12:54:20 pm
i think its too late to remind u guys that exam discussion only takes place 24 hours AFTER the exam!!
u finished discussing the paper and are about to leave now :P
Well.. It was already started lol. So, I thought it is already allowed for discussion? >_<
Post by: ilmarien on November 16, 2009, 01:01:35 pm
Whoops, sorry. I also thought that it's already okay to discuss it.
Post by: Q80BOY on November 16, 2009, 01:08:49 pm
Post by: falafail on November 16, 2009, 01:32:14 pm
The velocity question was actually to just use your ruler to draw the lines D: And you can actually double check by using the following formula :
Let vR be the resultant velocity, vx be the horizontal velocity and vy be the vertical velocity.
vR = Square root of (vx2 + vy2)
Then the horizontal angle can be found by tan= vy/vx
The vertical angle then can be obtained by 90 -
nono, not the vector diagram thing. the one before, the second part. i tried using the v2 = u2 blahblahblah formula but i didn't get it right :(
oh well.
Post by: Tyserius on November 16, 2009, 02:27:57 pm
Post by: falafail on November 16, 2009, 02:37:59 pm
It's because the vertical component begins with 0. So v =
yessss i knowwwww i'm saying i couldn't get the answer right (6.22 or whatever it was)
i left that though so i'll prolly get marks for it.
Post by: MaNi_DaDuDe on November 16, 2009, 05:47:22 pm
I made sure.
Post by: vince_24 on November 16, 2009, 07:27:55 pm
Post by: Hwa1 on November 16, 2009, 07:42:13 pm
and the phase difrnce was 180 degree or pi/2 (antiphase)
and the amplitude was just A, same as the other point o.O
Post by: Dooraven on November 16, 2009, 10:54:04 pm
Post by: vince_24 on November 17, 2009, 01:40:14 am
Post by: kratos009 on November 17, 2009, 01:52:58 am
Hey tyserius, i was wondering which variant paper you did?
Post by: vince_24 on November 17, 2009, 02:42:42 am
I am talking variant 2 here.
Post by: kratos009 on November 17, 2009, 03:41:43 am
Post by: Tyserius on November 17, 2009, 04:45:53 am
Yeah variant 2. I'm not exactly sure but i put 180 degrees, now that i think about it i think it is 270, cause the first particle is around 45 degrees from the start and the second particle is 45 degrees from the end. so together that's 90 degrees and 360-90= 270 degrees between them. But i'm pretty sure that the amplitude is -A because it has the same amplitude as the first particle but in a different direction, opposite direction so -A.
Erm in a wave particles will still oscillate back up? So why negative A? The particles will still have maximum positive displacement so shouldn't the amplitude be A? And aren't they asking for the amplitude of the wave?
Post by: kratos009 on November 17, 2009, 05:05:51 am
Plus I don't really want to think too much into the physics paper, what's done is done. I still got my Chemistry to go :(. Lucky you tyserius you've finished :).
Post by: Dooraven on November 17, 2009, 07:40:32 am
Amplitude is the maximum displacement. Antinode is place of maximum displacement. The point wasn't at an antinode so how exactly would the amplitude be A? Please enlighten me. Thanks.
The Question said the Amplitude of X is a A, not the maximum displacement. Y has the same magnitude of X but in a different direction so its A or -A. An amplitude is the maximum displacement of a particle in a wave, in a stationary wave the position of the particle does not change as it is not moving (hence stationary wave) therefore the displacement of the particle is the same as its amplitude.
The phase difference between the two points is 180 degrees. 270 would be correct if this was a progressive wave. However as this is a stationary wave the points can only vibrate with a 180 or 0 degrees phase difference because the phase difference between of any two points between any 2 nodes is zero. See here: http://www.btinternet.com/~melee3d/revision/physics/wavebehaviour.pdf under "Standing Waves"
Post by: MaNi_DaDuDe on November 17, 2009, 10:31:29 am
http://www.btinternet.com/~melee3d/revision/physics/wavebehaviour.pdf under "Standing Waves"
Nice link.
Wish I had seen that article before the exam. . . > . <
Post by: AndrewCedric on November 17, 2009, 11:01:17 am
And so the phase difference is 180 degrees?? if it is.. YEAHHHHHH.. Cause 270 degrees would be too vague. They only say state and there
is only 1 mark.. so i thought its 180 degrees..ahahah
Post by: astarmathsandphysics on November 17, 2009, 12:37:24 pm
Post by: astarmathsandphysics on November 17, 2009, 12:41:14 pm
Post by: MaNi_DaDuDe on November 17, 2009, 12:46:42 pm
I didnt realise this was about the paper just sat
What do you mean?
Post by: josephwhite on November 17, 2009, 01:26:44 pm
Post by: Tyserius on November 17, 2009, 02:24:20 pm
I remembered that in a past exam they had asked the amplitude on a part of the wave which was in the 'negative zone' and they had answered it as negative amplitude. I think the question was asking the displacement of that particle at that instant, and considering displacement is a vector quantity it was necessary to give the it as negative amplitude. I'm not 100% certain but i'm pretty sure that's what you have to do.
Plus I don't really want to think too much into the physics paper, what's done is done. I still got my Chemistry to go :(. Lucky you tyserius you've finished :).
Haha yes yes I'm a lucky man. :D But in this case it's amplitude, I think it's just A. Bah who cares, it's already over xD Err I did the variant where the wave question had like L and the points are like 1/8L from respective ends.
Post by: highly_ambitious on November 17, 2009, 02:52:39 pm
Haha yes yes I'm a lucky man. But in this case it's amplitude, I think it's just A. Bah who cares, it's already over xD Err I did the variant where the wave question had like L and the points are like 1/8L from respective ends.
what was the frequency and phase difference for that question? I wrote 'f' for frequency and 45 deg. for phase diff. Is it correct?
Post by: AndrewCedric on November 17, 2009, 03:33:46 pm
Post by: efafa on November 17, 2009, 04:06:15 pm
Hey, Tyserius even i did the same variant which u are talking aboutfrequency was f and phase difference i think was 1/2pi.
Haha yes yes I'm a lucky man. But in this case it's amplitude, I think it's just A. Bah who cares, it's already over xD Err I did the variant where the wave question had like L and the points are like 1/8L from respective ends.
what was the frequency and phase difference for that question? I wrote 'f' for frequency and 45 deg. for phase diff. Is it correct?
Post by: Tyserius on November 17, 2009, 05:19:21 pm
Yea.. its f for the frequency.. But not sure for the phase. I wrote 180 degrees which is supposed to be the correct one. No 45 is wrong. The possible options are 180 / 270 degrees. Of course only 1 answer is correct. Not sure which one it is.
The answer is 1.5
Post by: AndrewCedric on November 18, 2009, 03:21:28 pm
Post by: lonelyboy on November 18, 2009, 04:43:04 pm
The answer is 1.5/ 270 degrees lol that's because you use the distance between the points / wavelength multiplied by 2
Hi Tyserius,
You seem really smart :D
What was the answer to what could be deduced about the formation of the stationary waves by the speed or something?
It was in the same question.
Thanks mate, cheers.
Post by: Tyserius on November 20, 2009, 07:02:05 am
Hi Tyserius,
You seem really smart :D
What was the answer to what could be deduced about the formation of the stationary waves by the speed or something?
It was in the same question.
Thanks mate, cheers.
Lol, I'm not that. Well, the answer is :
A wave is incident from the oscillator and travels towards the other end P and then reflected back towards the oscillator. The oscillator would also be causing more waves. As the two waves travel in opposite directions, they happen to experience superposition and form a stationary wave. The speed calculated is the speed of the incident wave or the reflected wave.
Post by: lonelyboy on November 21, 2009, 06:49:56 pm
Lol, I'm not that. Well, the answer is :
A wave is incident from the oscillator and travels towards the other end P and then reflected back towards the oscillator. The oscillator would also be causing more waves. As the two waves travel in opposite directions, they happen to experience superposition and form a stationary wave. The speed calculated is the speed of the incident wave or the reflected wave.
Thanks mate ;)
Post by: ilmarien on November 23, 2009, 08:53:55 am
Post by: falafail on November 23, 2009, 12:14:36 pm
Dang. I wish I didn't re-take Physics. I was trying to get a higher score and I think I'll end up with a far lower one and I've wasted a few poundsterling for it.
me too. :-\
Post by: Tyserius on November 25, 2009, 07:00:44 pm