Problem Solving Strategies

Anonymous

12:52 AM

@YashasSamaga Same here :P I'm getting around 250 in total

Anonymous

Me too getting about 100 in chem and phy

Anonymous

I too screwed up maths

Anonymous

Actually it was too lengthy...the maths paper

Yashas Samaga

3:57 AM

I got 30 in math lol

Madhuchhanda Mandal

4:14 AM

Done the 10GHz microwave question?

(Observer moving half the speed of light towards a source of stationary 10 GHz microwave source. Find the frequency recorded by the observer.)

Isn't it using Doppler effect?

Anonymous

@YashasSamaga How much are you getting in total?

Anonymous

@MadhuchhandaMandal It is.

Anonymous

Physics paper was damn easy :-P

Anonymous

Now the race for advanced begins =D

Yashas Samaga

@MadhuchhandaMandal nope

Doppler formula for sound won't work

The question says the velocity to be c/2

You need to consider relativistic effects

Anonymous

4:24 AM

@YashasSamaga Doppler's effect for light...

Yashas Samaga

the formula is

f = f*sqrt((1 + v/c)/(1 - v/c))

Anonymous

Obviously, at c/2 you need to consider relativistic effects

Anonymous

Relativistic Doppler effect

The relativistic Doppler effect is the change in frequency (and wavelength) of light, caused by the relative motion of the source and the observer (as in the classical Doppler effect), when taking into account effects described by the special theory of relativity. The relativistic Doppler effect is different from the non-relativistic Doppler effect as the equations include the time dilation effect of special relativity and do not involve the medium of propagation as a reference point. They describe the total difference in observed frequencies and possess the required Lorentz symmetry. == ...

Anonymous

That was easy :-P

Anonymous

I always advise people to remember the basic derivation rather than mugging up the formulas...

Anonymous

4:28 AM

The formula for sound uses many asssumptions

Anonymous

And people directly memorize that...lel

Anonymous

I guess someone from kota will get full marks in jee main :/

Madhuchhanda Mandal

And Cp-Cv=R?

Anonymous

Na^

Anonymous

LOL

Anonymous

4:30 AM

so many people made that mistake

Yashas Samaga

@MadhuchhandaMandal They are bad people :(

Madhuchhanda Mandal

Then?

Yashas Samaga

The question said specific heat

not molar specific heat

:(

Madhuchhanda Mandal

Oh!!!

Yashas Samaga

but they used the wrong notation

Madhuchhanda Mandal

4:31 AM

nR

Anonymous

They gave it to confuse us

Yashas Samaga

a capital C stands for molar

Anonymous

Cp is "specfic heat"

Yashas Samaga

>.<

Anonymous

not molar specfic heat

Yashas Samaga

4:31 AM

I got that wrong

Anonymous

you ? ^

Anonymous

lol

Anonymous

even i was going to

Yashas Samaga

I marked the answer as R after 3 seconds

Anonymous

it was just stupid

Yashas Samaga

4:32 AM

read the Q, marked the answer

Madhuchhanda Mandal

Absolutely... I always encountered Cp to be specific molar heat

Yashas Samaga

@MadhuchhandaMandal IT IS!

even wikipedia uses the capital C for molar specific heat

Anonymous

forget it...it was just stupid

Yashas Samaga

small c for specific heat

I marked two answers wrongly in the OMR in chem section

I mark the answers in Q paper first then copy them down to the OMR at once

to save few minutes

Anonymous

@YashasSamaga But you know, they would not ask Cp-Cv=R in jee mains...:-P

Yashas Samaga

4:33 AM

I had skipped a Q

I forgot to leave space in the OMR for that Q

Anonymous

That's common sense

Anonymous

But we were in a hurry

Yashas Samaga

@blue check last year's paper; you can expect stupid questions

Anonymous

@YashasSamaga like?

Madhuchhanda Mandal

And The man growing to giant?

Yashas Samaga

4:34 AM

relationship between alpha and beta for transistors

@MadhuchhandaMandal 9?

His size increases by 9 in all dimensions.

Madhuchhanda Mandal

Like CE config Phase dufferencw

Yashas Samaga

180

Therefore, his volume increases by 9^3

His area increases by 9^2

Madhuchhanda Mandal

Yeah that was (CE config) was a stupid question

Yashas Samaga

stress = F/A = mg/A = density * V * g/A

stress = density *g * V_original * 9^3/A_original * 9^2

Anonymous

Just consider the man as a block

Anonymous

4:35 AM

With cylindrical legs

Yashas Samaga

it does not matter

Madhuchhanda Mandal

I considered that

Yashas Samaga

needn't be a block

can be anything

Anonymous

You can consider him to be a sphere also

Anonymous

Fat man

Anonymous

4:36 AM

:-D

Anonymous

Or a rod

Anonymous

Lol

Madhuchhanda Mandal

The upper part of the man's weight remains constant

Yashas Samaga

I am still sad becaz of math section

30 marks

Anonymous

maths was easy toh

Anonymous

4:36 AM

why 30?

Yashas Samaga

how the hell

@blue Everything was lengthy. I was jumping b/w questions.

Anonymous

i got around 60

Yashas Samaga

If you give me 1 extra hour, I wud get 100 :P

Anonymous

hmm

Yashas Samaga

I was in panic mode

Anonymous

4:37 AM

1 extra hour? The guy beside me finished the paper in 2 hours..he is gonna be in top 10 this year

Yashas Samaga

so I solved few questions to ensure that I get minimum cutoff marks for that section

@blue what?! impossible

Anonymous

@YashasSamaga Not at all...the paper was too easy and the guy beside me is superhuman

Yashas Samaga

I am going to write JEE Main again next year :D

Anonymous

he is from my coaching center

Anonymous

and he won all the three olympiads

Yashas Samaga

4:39 AM

I would take 5 mins on average for each question.

in math section

Madhuchhanda Mandal

Ohhhhhhh.... They have said density constant :|

Yashas Samaga

I am getting 270 in B Arch

Anonymous

BArch?

Anonymous

gonna be an architect?

Yashas Samaga

paper 2

nope

Anonymous

4:40 AM

ow

Anonymous

:-)

Anonymous

Why did you give that?

Yashas Samaga

270/290

*270/390

Anonymous

Barch paper is always easy :-P

Yashas Samaga

more ranks :P

@blue becaz I want more numbers

Anonymous

4:40 AM

I have seen dumb students who fail in jee mains getting 250 in barch

Yashas Samaga

@blue Time is the problem in B Arch.

Anonymous

lol

Anonymous

It is that easy

Yashas Samaga

you can get 90 marks in drawing

Anonymous

i see

Yashas Samaga

4:41 AM

40 in GK

160 in GMAT

Anonymous

@YashasSamaga anyhow, iit bombay cse pakka toh ? :D

Anonymous

good luck

Yashas Samaga

60 in GK

Anonymous

for advanced

Yashas Samaga

@blue :| nope

I had 300+ in mock tests

idk how did I end up with 220-250 in the actual exam

Anonymous

4:42 AM

How much was your rank last year?

Anonymous

in advanced?

Yashas Samaga

I'll tell after we get this year's rank

Anonymous

ok

Yashas Samaga

becaz I don't want this to happen: Rank X last year, Rank Y this year and Y > X

I got 959 in KVPY :(

I moved from 358 to 959 lol

Anonymous

Oh, i didn't appear for kvpy as it had biology

Yashas Samaga

4:44 AM

I got worse after dropping :D

@blue Biology is optional; you need to attempt 3 subjects out of 4.

Anonymous

@YashasSamaga Oh! I am talking about class 11

Yashas Samaga

I would estimate that there are around 350 biology students in top 500 ranks

but biology students have advantage

Anonymous

In class 12 I was too busy

Madhuchhanda Mandal

@YashasSamaga "I got worse after dropping " why?

Yashas Samaga

When I was in class 11, NTSE was two weeks before KVPY

Anonymous

4:45 AM

class 1?

Anonymous

lele

Yashas Samaga

@MadhuchhandaMandal becaz I am scoring less than what I did last year

You can perform this action again in 22 seconds.

Madhuchhanda Mandal

959>358

Isn't it?

Yashas Samaga

bigger rank is bad lol

Madhuchhanda Mandal

Oh... Rank

Anonymous

4:46 AM

Okay, go back to your studies guys

Yashas Samaga

kvpy.iisc.ernet.in/main/results-2016.htm

Anonymous

All the best

Anonymous

For jee advanced

Anonymous

:-)

Yashas Samaga

ty s2u

Anonymous

4:47 AM

We meet next at the IITs :-)

Anonymous

cya

Yashas Samaga

@MadhuchhandaMandal how much are you scoring in math section?

Madhuchhanda Mandal

6:16 AM

52

Anonymous

7:31 AM

0

Q: How to find the least count of Vernier Calipers when Vernier Scale Divisions are greater than Main Scale Divisions?

When Vernier Scale Divisions are smaller than Main Scale Divisions, the least count is given by $1 \text{MSD} - 1 \text{VSD}$. But what if say, $3 \text{VSD}=5 \text{MSD}$ ? Do we write the least count as $1 \text{VSD} - 1 \text{MSD}$ ?I am having difficulty in visualizing the situation. Can so...

Anonymous

Someone try to answer this ^

Madhuchhanda Mandal

7:59 AM

does question come from magnetic dip inclination or curie temperature in jee advanced

?

Anonymous

@MadhuchhandaMandal na

Anonymous

bogus questions are not asked in advanced

Madhuchhanda Mandal

Yeah... Jee main is a bit of memory tester I am feeling now

And calculation skill checker

Anonymous

@MadhuchhandaMandal Obviously

Anonymous

Jee main tests your basic knowledge

Madhuchhanda Mandal

9:00 AM

In the 10GHz question, what is the apparent velocity of microwave noted by the observer?

Anonymous

12:23 PM

@MadhuchhandaMandal 17...

Madhuchhanda Mandal

1:01 PM

"17..." Means?

Anonymous

1:13 PM

Man, go and check the solutions

Anonymous

allen.ac.in/jee-main-2017/…

Anonymous

@MadhuchhandaMandal

Madhuchhanda Mandal

3:10 PM

@blue "velocity" Please re-read the question I asked.

Anonymous

3:54 PM

19. Physics | Dopler's Effect | Doppler's Effect in Light | by Ashish Arora

►

Anonymous

Apparent velocity will be just relative velocity...

Anonymous

But that doesn't even matter here

Anonymous

What matters is apparent wavelength of the wave received

Anonymous

@MadhuchhandaMandal

Madhuchhanda Mandal

@blue I am not talking about the question nor am I interested in its solution (I could solve it finally when you told that relativistic considerations should be taken into account, actually, I never knew Special Theory of Relativity is in JEE syllabus.). Anyway, I am speaking with reference to the question not about the question.

Anonymous

5:22 PM

@MadhuchhandaMandal So, is it clear now?

Anonymous

Or you have some confusion?

Anonymous

Apparent velocity of the the microwave will be $c$.

Anonymous

Light's velocity is independent of frame...

Madhuchhanda Mandal

5:57 PM

And apparent velocity of the source of microwave?

@blue "is it clear now?" - what?

Sakazuki Akainu

6:09 PM

what's up?

damn, so dead

Madhuchhanda Mandal

@SakazukiAkainu Whats up?

Expected jee score?

Madhuchhanda Mandal

7:29 PM

@blue ok let's go back to our good old sound. Let there be a source s emitting 300 Hz sound travelling through air at 300 m/sec. Let's suppose two cases : case 1) Vsource =150 m/sec and observer is stationary. Case 2) Vobserver = 300 m/sec and source is stationary. Will the nature of sound received by the observer from the source be same in both the cases?

(In both the cases, its assumed that separation between observer and source decreases)

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Problem Solving Strategies