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Author Topic: ALL PHYSICS DOUBTS - POST HERE !!  (Read 230675 times)

Offline igext

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1485 on: May 25, 2010, 07:50:40 pm »
Quote from: 33oomar on May 25, 2010, 07:48:29 pm
Guys.. I need help in
question 39   may/june 2007 paper 1
Please help meeeeee :(
20 hours means 4 half lives so double the value present now 4 times ( x2 x2 x2 x2 )
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Offline Vin

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1486 on: May 25, 2010, 07:51:25 pm »
Quote from: Adzel on May 25, 2010, 07:45:24 pm
see attached...

ok so density = mass/volume

in the diag . the initial volume if 100 cc after pouring the liquid its 140 to mass of water = 140 - 100 = 40 cc

volume on diag is 60 cc

density = mass/volume

=40/60
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Offline Vin

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1487 on: May 25, 2010, 07:52:10 pm »
Quote from: igext on May 25, 2010, 07:44:17 pm
my teacher said the current is directly induced in the 2ndry coil with out the help of the core

nop .. not possible ..
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Offline igext

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1488 on: May 25, 2010, 07:53:18 pm »
Quote from: ~VIN1094~ on May 25, 2010, 07:52:10 pm
nop .. not possible ..
now there is an alternating field due to the 2ndry coil? why duznt this affect the current in primary coil?
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Offline Shazizzzle

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1489 on: May 25, 2010, 07:54:02 pm »
Quote from: 33oomar on May 25, 2010, 07:48:29 pm
Guys.. I need help in
question 39   may/june 2007 paper 1
Please help meeeeee :(

The half-life is 5 hours. That means it takes 5 hours for half the sample to decay.

They are asking about 20 hours before.
After the 20 hours, it was 0.48 g.
How much was it 5 hours before? It would be double, as 5 hours is the half life.
So, 0.48 X 2= 0.96.
0.96 was 5 hours before.
What about ten hours before the initial?
That would be double of the 5 hours before one. i.e 0.96 X 2 = 1.92.

So, 10 hours ago, it was 1.92.
What about 15 hours before? That would be 5 more behind the 10 hours one.
So, 1.92 X 2 = 3.84

And thus for 20, 3.84 X 2 = 7.68

See, in every 5 hours, it doubles.
You can't just multiply 0.48 by 4.
It DOUBLES every 5 HOURS.
So, you have to double it, in each step, when going backwards.
« Last Edit: May 25, 2010, 08:13:41 pm by Shazizzzle »
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Offline haris94

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1490 on: May 25, 2010, 07:54:24 pm »
Quote from: igext on May 25, 2010, 07:44:17 pm
my teacher said the current is directly induced in the 2ndry coil with out the help of the core

thats not true
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Offline CatAly$t

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1491 on: May 25, 2010, 07:54:44 pm »
does anybody have a list of formulas for physics??

and any tips....
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Offline the_grim_reaper

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1492 on: May 25, 2010, 07:55:49 pm »
Quote from: Shazizzzle on May 25, 2010, 07:54:02 pm
The half-life is 5 hours. That means it takes 5 hours for half the sample to decay.

They are asking about 20 hours before.
After the 20 hours, it was 0.48 g.
How much was it 5 hours before? It would be double, as 5 hours is the half life.
So, 0.48 X 2= 0.96.
0.96 was 5 hours before.
What about ten hours before the initial?
That would be double of the 5 hours before one. i.e 0.96 X 2 = 1.92.

So, 10 hours ago, it was 1.92.



Shaz don't get mad but the answer is 7.68 g :D
What about 15 hours before? That would be 5 more behind the 10 hours one.
So, 1.92 X 2 = 3.84

And thus for 20, 1.92 X 2 = 3.84

See, in every 5 hours, it doubles.
You can't just multiply 0.48 by 4.
It DOUBLES every 5 HOURS.
So, you have to double it, in each step, when going backwards.

Shaz don't get mad but it's 7.68 g :D.
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Offline Malak

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1493 on: May 25, 2010, 07:56:07 pm »
Do we need to know the logic gates stuff for ppr 1?
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Offline igext

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1494 on: May 25, 2010, 07:56:45 pm »
Quote from: haris94 on May 25, 2010, 07:54:24 pm
thats not true
aryt... so if they ask about the function of the core worth 2 marks wat will u write down?
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Offline omair

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1495 on: May 25, 2010, 07:56:56 pm »
any one can u tell me how to find the needle compss deflection when place near stright conductor
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Offline Adzel

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1496 on: May 25, 2010, 07:57:24 pm »
Quote from: ~VIN1094~ on May 25, 2010, 07:51:25 pm
ok so density = mass/volume

in the diag . the initial volume if 100 cc after pouring the liquid its 140 to mass of water = 140 - 100 = 40 cc

volume on diag is 60 cc

density = mass/volume

=40/60

Ohh I thought it was a + sign, and I didn't relize that it is a / sign...lol
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Offline the_grim_reaper

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1497 on: May 25, 2010, 07:57:37 pm »
Quote from: igext on May 25, 2010, 07:56:45 pm
aryt... so if they ask about the function of the core worth 2 marks wat will u write down?

They won't cause it's paper 1 tomorrow :D :D.
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Offline diva_sparkles

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1498 on: May 25, 2010, 07:58:13 pm »
Quote from: ang3l on May 25, 2010, 07:56:07 pm
Do we need to know the logic gates stuff for ppr 1?

nvr saw thm but just learn it in case it appears!!
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Offline 8T

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1499 on: May 25, 2010, 07:58:54 pm »
Folks..Anyone could assist me withMay 07 q 27 ??
Ans is B but i chose A .. Why is it the way it is?
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