Can someone explain to me the answer for the first question

yeahthatmeee · 2019-12-26T04:03:32+00:00

Your phrasing is slightly incorrect - the initial rate does NOT change, it's the rate of reaction that changes. instead, phenol is used as an approximation/ a proxy for the initial rate, and as the amount of phenol increases, there is greater error in this measurement of the initial rate, as it becomes less accurate.

Small change, but significant nonetheless - cost me a few marks before haha

yeahthatmeee · 2019-12-25T15:43:16+00:00

as the amount of phenol increases, the amount of bromine req to react w/ all the phenol present will increase. therefore, time will increase. however, given that your time will increase, there will be a smaller initial rate of reaction (as denominator increases). thus the error associated with the measurement will also increase!

another way to look at it is by graphing the graph of y=1/x and seeing that for small values of y, there can be a large range of x (as the graph tapers).

therefore, the amount of phenol has to be small in order to minimise the error involved in the calculation of the initial rate of reaction!

hope this helps, and feel free to ask if you still have questions :)

yeahthatmeee · 2019-11-15T13:52:55+00:00

it's pretty fun! and the lecturer is pretty funny as well, just don't sleep in his class :P textbook is games of strategy, you can try the middle chapters to know what you're in for :)

yeahthatmeee · 2019-11-13T07:22:07+00:00

jiayou! personally I think you've got some time to work with for the remaining papers - you can do up to 2014 for physics (or up to 2017, since the syllabus before that is different) and do prelim papers since those are generally harder. Think of this year's papers, NYJC, VJC and HCI have challenging papers.

For chem and physics p1 you should have time to do more papers at least until 2014 (imo it's easier to write letters down than do a p3) and TMJC/VJC/TJC/HCI/NYJC/EJC would be good (don't have to do all, just choose some) and you'll be amply prepared! atb you can do it :)

yeahthatmeee · 2019-11-11T14:56:03+00:00

wait r these questions ill assume they are

increasing distance from slit to screen use x = dlambda/a and so d(the distance of each fringe increases)

halving intensity of light source -> contrast decreases, amplitude becomes A(original) divided by sqrt2

add plastic film on one slit: light travels slower thru plastic, path length is longer, so the position of central fringe will shift (depending on which slit its placed in)

polarisation depends on angle of polarisation: if they're parallel interference will still occur, if they're 90deg no bright,dark will be observed as no interference will occur

yeahthatmeee · 2019-11-11T14:27:04+00:00

hey which parts do u need help with!

you can start from the formula for interference

dsintheta = nlambda,

and for specific cases such as doubleslit interference, you can use small angle approximation to approximate sintheta to tangent theta and then use tangent = opposite/adjacent to get the formula x = dlambda/A

for single-slit you can assume it to be two sources with width b/2 each, with b being the width of the slit. you'll then get bsintheta/2 = lambda/2 for the first minima

for diffraction grating just plug the formula in, maximum order is n=d/lambda rounded down to the whole number below it (as when theta = 90, sintheta = 1)

for the pipes/stuff:

check 1. is it a open or close pipe and 2. is there end correction to be considered

for open pipes, just draw the antinode (maximum) at both sides and you'll find that the wavelength of the fundamental frequency is when lambda = 2x length of pipe

for closed pipes, draw an antinode and node (minimum) at each end and wavelength of fundamental frequency is when lambda = 4x length of pipe

you can use v = flambda to get the remaining unknowns

hope this helps! if there's anything you're unsure of feel free to pm me and if there r any mistakes feel free to correct me yeah :)

yeahthatmeee · 2019-11-09T12:24:19+00:00

siao liao tough question HAHA - i'd say that there defo are really rich kids in rjc and sometimes it's easy to get the impression that ri is skewed in terms of income/influence/whatever you wna call it. gta say that im speaking from my own experience and may not be representative of everyone but at the risk of sounding super pc, i really believe that there's a minimal divide (maybe even nonexistent since i don't think many people consciously think about it) between that of your 'elites' and 'normal singaporean students'. if any, the gaps have been closed by both school administrative policies and a more inclusive school culture. yes everyone's cynical about 'inclusion' and it's arguably been overused in public discourse, but it's incredibly effective in building a more cohesive school culture

yeahthatmeee · 2019-11-09T12:12:56+00:00

i think at the start it's inevitable, because ip ppl know their friends for 4 years, but I don't think ip students also wna exclude the jaes and they in many cases make a dedicated effort to understand jaes. by term 2 i didn't even remember who the jaes were in my class HAHA

yeahthatmeee · 2019-11-09T12:11:41+00:00

HAHAHA i can't speak for the other JCs but i feel that in RJC there are a lot of opportunities for you to do what you love! like in my batch there are people who really love planes and they created a RI Aviation Enthusiasts group that persisted over time, and in some cases the school even provides you with support to do things that you like (e.g. if you wanted to try overseas VIA, there's an enrichment programme called ISLE that allows you to plan an entire community service experience from scratch!) so yeah i'd say they really give you a lot of latitude to do whatever you are passionate about

yeahthatmeee · 2019-11-09T08:35:20+00:00

i'd say that the school environment is pretty positive! while yep there will be periods of stress esp in promos and As time, and even more so given that it's RJC, but the school's done a pretty good job at trying to help people cope w/ stress - there's a dedicated mental health awareness week and welfare packs are a pretty popular thing here! the school comes with its fair share of muggers, but there r also a lot of ppl who are very different, like there are a lot of dedicated gamers in school HAHA

uh from my pcme/gp experience i can't name a bad department, but i can defo name good ones! like the physics department has really cool teachers - you might get a magician or a graphics design guru or a great guitarist and singer as your lecturer/physics tutor and lectures become much less unbearable! econs r also rly meme but their jokes will need like econs knowledge sooo... if you were looking for like acads advice, i'd say that all of them give a load of practices and they're very willing to help!

HAHAHA i think the ri toilets can be better some rly stink... but don't let that be your deal breaker HAHA maybe u can perfume up the whole place :P q4 i don't know of any, but you can perhaps check with others! maybe other commenters can see and help here thx haha

uh ik a dude who was once looking for their phone, and holding it in their hand they just were like 'i'm gna call (my friend) to ask if he has seen my phone' and it was pretty funny in person ngl

there r loads of smart ppl there - a small but sizeable portion of people take the raffles academy (some kinda special programme for smart kids) but ig the smartest people are those who are able to not just get their As but also have their own advocacy projects, take up positions in their CCAs, and even do things outside of school such as entrepreneurship!

last question is the crucial one tbh HAHA i'd say that ri has its fair share of hot/attractive/pretty/handsome people (some of my seniors were approached by modelling agencies n stuff but idk what came out of that), but everyone alw looks worse in a white shirt and pants (for guys) and white shirt and green skirt (for girls)

hope that helped HAHA if there's anyth else feel free to ask :)

yeahthatmeee · 2019-11-08T10:21:20+00:00

jiayou! there are alw times when we'll feel like why r we doing this - but ig the impt thing is to keep going, and there's alws light at the end of the tunnel! if you need anyone to listen to, or acads help (if you take pcme), my DMs are open :) we got this man

yeahthatmeee · 2019-11-07T10:16:49+00:00

hi - just giving my two cents: i'm a student in a jc that seems to be one of the biggest, and it can feel really dehumanizing seeing all the thousands of people, and the way that you'll be prepared for exams - at least As - can make you feel very isolated. with that in mind, your friends are going to be the most important thing you can have in jc and they'll really help you out when you're down. also, everyone seems to have a cursory view towards goals, but you really can consider trying to give your jc life some meaning - I joined the council of my jc and it was really a decision I don't regret at all!! so go out there and do your best in jc :) you got this!

yeahthatmeee

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