IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => IGCSE/ GCSE => Sciences => Topic started by: moon on October 31, 2009, 02:23:58 pm

Title: igcse physics ppr 6 DOUBT
Post by: moon on October 31, 2009, 02:23:58 pm: please can somebody help me Nov. 98 Q3. a
Title: Re: igcse physics ppr 6 DOUBT
Post by: nid404 on October 31, 2009, 02:35:36 pm: Quote from: moon on October 31, 2009, 02:23:58 pm
please can somebody help me Nov. 98 Q3. a

I don't hve the paper....can u upload it
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on October 31, 2009, 02:45:58 pm: here is the question.
Title: Re: igcse physics ppr 6 DOUBT
Post by: nid404 on October 31, 2009, 02:54:16 pm: R is proportional to l
if u take 5ohm/p, length will be 0.6m for 3ohms
like if u take 10ohm/m.....length for 3 ohms would be 3/10...0.3 m
and if u take 20ohm/m....length for 3ohms would be 3/20.. 0.15m....I think would be suitable.

For least resistance in the resistor in itself....a smaller length would be preferred.

If anyone has another answer and a reason to justify it....go ahead...m not a master in physics :P.....but from whatever knowledge i have...I would chose this
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on October 31, 2009, 03:00:51 pm: how did u calculated the length?
Title: Re: igcse physics ppr 6 DOUBT
Post by: nid404 on October 31, 2009, 03:02:03 pm: Quote from: moon on October 31, 2009, 03:00:51 pm
how did u calculated the length?

Just cross multiply.
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on October 31, 2009, 03:07:45 pm: thanks a lot.
Title: Re: igcse physics ppr 6 DOUBT
Post by: nid404 on October 31, 2009, 03:08:16 pm: Quote from: moon on October 31, 2009, 03:07:45 pm
thanks a lot.

ya sure...np
Title: Re: igcse physics ppr 6 DOUBT
Post by: holychalice on October 31, 2009, 03:11:25 pm: but i think u shud choose a wire with more length ... cuz if u choose short length wires it cannot be accurate
as u did 0.6, 0.3 nd 0.15 .... so d 5ohm/m shud be used ...
isnt it ?? i might be wrong ??
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on October 31, 2009, 03:16:17 pm: yes, M.@.N.B.i.R. I guess u r rite!!! thanks 4 ur help.
Title: Re: igcse physics ppr 6 DOUBT
Post by: holychalice on October 31, 2009, 03:16:58 pm: do u have d mark scheme for this ppr ???
can u check .. nd lemme noe ??
Title: Re: igcse physics ppr 6 DOUBT
Post by: Ghost Of Highbury on October 31, 2009, 03:21:26 pm: yes, it should be W1 as a 60cm wire can be measured more accurately.
Title: Re: igcse physics ppr 6 DOUBT
Post by: Ghost Of Highbury on October 31, 2009, 03:22:30 pm: Quote from: M.@.N.B.i.R. on October 31, 2009, 03:16:58 pm
do u have d mark scheme for this ppr ???
can u check .. nd lemme noe ??
nd can u temme hw will u identify d length of d wire to be used ?

the length can be found out be simple cross multiplication

5ohms - 1m

3ohms - 3/5m = 0.6m = 60cm
Title: Re: igcse physics ppr 6 DOUBT
Post by: holychalice on October 31, 2009, 03:23:19 pm: woooohooo .. got it rite ...
yaa ... understood dat Thanks ...
Title: Re: igcse physics ppr 6 DOUBT
Post by: xTremep on November 01, 2009, 08:13:33 pm: Quote from: A@di on October 31, 2009, 03:22:30 pm
the length can be found out be simple cross multiplication

5ohms - 1m

3ohms - 3/5m = 0.6m = 60cm

and what is the reason?
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on November 02, 2009, 09:17:54 am: please can u help in Jun.1999 ppr 6 Q.3 (a) & (b ii) ???
Title: Re: igcse physics ppr 6 DOUBT
Post by: holychalice on November 02, 2009, 09:20:35 am: can u put up d paper ?? or d question ??
Title: Re: igcse physics ppr 6 DOUBT
Post by: nid404 on November 02, 2009, 09:21:46 am: Quote from: moon on November 02, 2009, 09:17:54 am
please can u help in Jun.1999 ppr 6 Q.3 (a) & (b ii) ???

yes please...i don'y have da paper
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on November 02, 2009, 09:33:38 am: ok, I will try.
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on November 02, 2009, 09:40:02 am: here is the question ???
Title: Re: igcse physics ppr 6 DOUBT
Post by: holychalice on November 02, 2009, 09:49:57 am: ok
1. a - Avg = (26.8 + 26.8 + 27 + 26.9 + 27 + 27) / 6 = 26.9 ^OC
- 0.1 ^OC
The largest temperature difference is very low ... Less than even 5% or even 1% of d avg temperature .. so we can take it as constant
b - 0 cm3 as the volume remained 14 aall d tym
3.1 x 2 = 6.2 cm3 This is because d volumes given are h/cm but we have a 2cm3 of tube so double.
13.9 x 2 = 27.8 cm3
Avg u can do it = 27.8/5 = 5.6 cm3

I guess this is d way ...
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on November 02, 2009, 10:02:11 am: Avg = (26.8 + 26.8 + 27 + 26.9 + 27 + 27) / 6 = 26.9 OC

why did u divide it by 6???

Avg u can do it = 27.8/5 = 5.6 cm3

and here why did u divide it by 5???
Title: Re: igcse physics ppr 6 DOUBT
Post by: holychalice on November 02, 2009, 10:09:06 am: c d table noe :
dere six values for room temperature :
for avg temperature .. u hav 6 observations ..
at 0hr , 1hr, 2hr, 3hr, 4hr and 5hr ...

nd divided by 5 ... cuz we r checking d rate of water lost in 5 hrs ... dats d experiment ... so its kept for 5 hrs ... ... so for 5 hrs .. 27.8 divided by 5 ...nd u hav 5 hrs of observation for d water loss so divided by 5

got it ?
read this again ... ive modified it
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on November 02, 2009, 10:13:41 am: Why don't we take the initial time ??? ???
Title: Re: igcse physics ppr 6 DOUBT
Post by: Ghost Of Highbury on November 02, 2009, 11:50:35 am: Quote from: moon on November 02, 2009, 10:13:41 am
Why don't we take the initial time ??? ???

ok..its simple ratio

27.8cm³ of water lost in 5 hours

how much lost in 1 hour?

5 hours - 27.8

1 hours - 27.8/5 *1 = 5.56cm³/h
Title: Re: igcse physics ppr 6 DOUBT
Post by: moon on November 02, 2009, 12:02:05 pm: I've got it. Thank u both 4 helping me. :)
Title: Re: igcse physics ppr 6 DOUBT
Post by: Ghost Of Highbury on November 02, 2009, 12:03:58 pm: Quote from: moon on November 02, 2009, 12:02:05 pm
I've got it. Thank u both 4 helping me. :)
ur welcome..