Author Topic: ALL PHYSICS DOUBTS - POST HERE !!  (Read 225310 times)

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2175 on: May 26, 2010, 08:19:27 pm »
Sorry, here it is: http://www.freeexampapers.us/IGCSE/Physics/CIE/2009%20Nov/0625_w09_qp_31.pdf

I don't understand how it is worked out.

10ai) Step up transformer obviously.

    aii) Less current, less electrical energy lost, less heat energy given out

    b) P = V*I, I = 55k/22k = 2.5

    c) Rate of loss formula, P = I^2R = 2.5^2*3  = 18.75

    d) The overall voltage reduced from 22K Volts due to the resistance of the wire, till it reaches the receiving end.

I know this is confusing sh*t, it had appeared in my paper! nov 09! V = 2.5*3 = 7.5

from wiki "For example, an electric space heater may very well have a resistance of ten ohms, and the wires which supply it may have a resistance of 0.2 ohms, about 2% of the total circuit resistance. This means that 2% of the supplied voltage is actually being lost by the wire itself."

       e) 22000 - 7.5 -7.5 = 21985 (2 times 7.5 because there are two wires, each voltage dorp = 7.5)
divine intervention!

Offline Naruto123

  • SF Immigrant
  • **
  • Posts: 71
  • Reputation: 86
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2176 on: May 26, 2010, 08:20:34 pm »
GUYZ do we have to change da temperature to kelvin or not ??? thx

Offline Vin

  • SF V.I.P
  • ********
  • Posts: 7914
  • Reputation: 52609
  • Gender: Male
    • Theory of Life - A new skew.
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2177 on: May 26, 2010, 08:22:38 pm »
guys i need help in q8 May / JUne 2007 Paper 3 Part B
PLEASE

b) i)

P =I V
I = P/V

=36/1

=3A

ii) V = IR

R = V/I

=12/3

= 4 ohm

iii) 1/R = 1/R1 + 1/R

1/R = 1/4 + 1/4

1/R = 2/4 = 1/2

so, R = inverse of 1/2 = 2 ohm


iv) E = P t

= 36 * 30

=1080 J



Offline Malak

  • Honorary Member
  • SF Farseer
  • *****
  • Posts: 4454
  • Reputation: 65534
  • A warm smile is the universal language of kindness
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2178 on: May 26, 2010, 08:23:06 pm »
If you are a man who degrades women then allow me to respectfully remind you that you came from ONE

Reminder to myself: Stop worrying and start working

SF magazine 2012 - Download here

Offline Adzel

  • SF Citizen
  • ***
  • Posts: 230
  • Reputation: 272
  • ALLAH IS THE GREATEST
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2179 on: May 26, 2010, 08:23:21 pm »
guys i need help in q8 May / JUne 2007 Paper 3 Part B
PLEASE

Offline mdwael

  • SF Immigrant
  • **
  • Posts: 115
  • Reputation: 144
  • Gender: Male
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2180 on: May 26, 2010, 08:23:31 pm »
Thanks a lot VIN your the best!!! :) :D
"We all want to be different, which makes us all the same"

Offline Vin

  • SF V.I.P
  • ********
  • Posts: 7914
  • Reputation: 52609
  • Gender: Male
    • Theory of Life - A new skew.
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2181 on: May 26, 2010, 08:23:43 pm »
GUYZ do we have to change da temperature to kelvin or not ??? thx

yes while using the formula ..

p1V1      p2V2
------ = -----
T1           T2

Offline Adzel

  • SF Citizen
  • ***
  • Posts: 230
  • Reputation: 272
  • ALLAH IS THE GREATEST
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2182 on: May 26, 2010, 08:26:22 pm »
yes while using the formula ..

p1V1      p2V2
------ = -----
T1           T2

only this one???

Offline Weaam

  • Mad Alice
  • SF Geek
  • ****
  • Posts: 411
  • Reputation: 2264
  • Gender: Female
  • What if I spoke alien, fluently? O.o
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2183 on: May 26, 2010, 08:26:35 pm »
Can anyone please please tell me the answer and draw the diagram of Q4 b in o/n 08 second varient?
Please and thank you!
- The man who smiles when things go wrong has thought of someone to blame it on. - Robert Bloch.
-I saw weird stuff in that place last night. Weird, strange, sick, twisted, eerie, godless, evil stuff... and I went in. - Homer
+ Rep me if i have been of any assistance to you ;D

Offline 33oomar

  • Newbie
  • *
  • Posts: 27
  • Reputation: 45
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2184 on: May 26, 2010, 08:27:06 pm »
b) i)

P =I V
I = P/V

=36/1

=3A

ii) V = IR

R = V/I

=12/3

= 4 ohm

iii) 1/R = 1/R1 + 1/R

1/R = 1/4 + 1/4

1/R = 2/4 = 1/2

so, R = inverse of 1/2 = 2 ohm


iv) E = P t

= 36 * 30

=1080 J



Oh thanks a lot dude ......... r u takin' paper 3 tomorrow

Offline Ashe

  • Newbie
  • *
  • Posts: 5
  • Reputation: 26
  • Gender: Female
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2185 on: May 26, 2010, 08:27:40 pm »
I don't really understand why we use a relay in circuits. When they ask why a relay is used in a circuit? what's the full answer to that?

And another question, i saw this in a past paper but couldnt find it again =S
When someone is driving in a car, and the car suddenly crashes. What's the energy change of the driver?
I know its from kinetic, but into what?


Offline eastrimx

  • Newbie
  • *
  • Posts: 3
  • Reputation: 13
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2186 on: May 26, 2010, 08:27:56 pm »
can someone help me with the question 4 in october/nov 2008 paper 3 first variant?

http://www.freeexampapers.us/IGCSE/Physics/CIE/2008%20Nov/0625_w08_ms_3.pdf
« Last Edit: May 26, 2010, 08:34:32 pm by eastrimx »

Offline dodi23

  • Before you meet your prince you have to kiss a lot of toads.
  • SF Master
  • ******
  • Posts: 1418
  • Reputation: 2963
  • Gender: Female
  • MAN made beer, GOD made weed. Who do you trust?
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2187 on: May 26, 2010, 08:29:12 pm »
I don't really understand why we use a relay in circuits. When they ask why a relay is used in a circuit? what's the full answer to that?

And another question, i saw this in a past paper but couldnt find it again =S
When someone is driving in a car, and the car suddenly crashes. What's the energy change of the driver?
I know its from kinetic, but into what?



into sound, heat nd potential energy :P
_________________________________
l__l__l__l__l__ll__ll__ll__ll__ll__l__l\_?_\___
l__dodi23's_ limousine___________________l=
""(@)@)''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''(@)

Offline Adzel

  • SF Citizen
  • ***
  • Posts: 230
  • Reputation: 272
  • ALLAH IS THE GREATEST
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2188 on: May 26, 2010, 08:29:43 pm »
Can anyone please please tell me the answer and draw the diagram of Q4 b in o/n 08 second varient?
Please and thank you!

Rondom Jerky Motion

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2189 on: May 26, 2010, 08:30:38 pm »
GUYZ , WHEN YOU ASK DOUBTS, PLEASE PROVIDE THE LINK TO THE PAPER, IT IS MUCH EASIER FOR THE PERSON TO ANSWER. PLEASE!

THANK YOU :D


@master math - Variant one says its micrometer.
divine intervention!