Author Topic: ALL CIE PHYSICS DOUBTS HERE !!!  (Read 172211 times)

Offline username

  • SF Geek
  • ****
  • Posts: 461
  • Reputation: 65535
  • Nobody is perfect.... I am Nobody.
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #780 on: June 07, 2011, 09:04:21 am »
how come the amplitude is times 2?
intensity= amplitude^2

Offline physichemaths

  • Newbie
  • *
  • Posts: 26
  • Reputation: 37
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #781 on: June 07, 2011, 09:09:49 am »
intensity= amplitude^2
yeah. I know. Then why is there 2 in Ip = 2kA^2?  Not the square one, i mean 2 in the front?

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #782 on: June 07, 2011, 10:23:45 am »
No, there are two different constants, k1 and k2. The "2" is not multiplied by A, it belongs to the constant k. k1 and k2
divine intervention!

Offline physichemaths

  • Newbie
  • *
  • Posts: 26
  • Reputation: 37
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #783 on: June 07, 2011, 10:41:33 am »
No, there are two different constants, k1 and k2. The "2" is not multiplied by A, it belongs to the constant k. k1 and k2
owh. I got it. Thanks a lot! :D

Offline JACKRABBIT

  • Newbie
  • *
  • Posts: 20
  • Reputation: 32
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #784 on: June 07, 2011, 12:11:43 pm »
Quote
8. XY - 40m - 12s
    XZ - 80m - 18s
80 = 18u + 0.5a*18^2
40 = 12u + 0.5a*12^2

Solve the simultaneous equations, by eliminating u and calculating a.

9. There's a little bit of guess work involved here.
Given it's inelastic, the rebound velocity won't be v. Say, 40% of energy is lost, say around 0.6v
Change = (-0.6v*2m) - 2mv = -3.2mv
SO the change is almost 3mv.
(Even if u take 0.7v, u won't get 4mv+)

15. Steady speed v, therefore weight is balanced by retarding force
mg = kv
v = mg/k
KE = 0.5mv^2 = 0.5m*(mg/k)^2 = m/2 * m^2g^2 /k^2 = m^3g^2 /2k^2

34. When x = 0, the voltage measured is across the whole of the wire, so it has to be V.
    when x decreases, and the pointer is moved at the right end of the part with resistivity p, the voltage is divided into 2 parts (p and 2p+3p)
   So the voltage across the length x is now, not V, but a lil less than V because some VOltage is lost in the remaining length of the wire.
Answer: B (note the graph is not a straight line because as x decreases, the resistance doesn't decrease proportionately)

---
23. frequency = 1/(time taken for 1 complete oscillation = 50m (check x-axis))
It covers 8m in 1 second (speed)
so 50m in 50/8 s = 6.25
That's its time period
Hence, frequency = 1/t = 1/6.25 = 0.16Hz
Speed = 2pi*a*f = 2pi*2*0.16 = 2.01m/s
KE = 0.5mv^2 = 4mJ
25. dsin45 = 3*lambda
d = 3lambda/sin 45 = 3sqrt(2)*lambda
maximum order of diffraction = dsin90 = n*lambda
n = d/lambda
n = (3sqrt(2)*lambda)/lambda = 3sqrt(2) = 4.24264.... ~ 4




WOW thanks man....ur good lol

AALSO...I know that a electric field with the positive plate earthed will still have a positive chargeon it...but what if a theres an electric field and the NEGATIVE plate is earthed??? will there still be a negative charge on it??? or will there be no charge on it...??

Offline wstrawberries

  • SF Immigrant
  • **
  • Posts: 54
  • Reputation: 66

Offline username

  • SF Geek
  • ****
  • Posts: 461
  • Reputation: 65535
  • Nobody is perfect.... I am Nobody.
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #786 on: June 07, 2011, 01:28:56 pm »
guys
do we have to learn the frequencies and wavelenghts of colrs of light?
like red, yellow... etc.?

Offline EMO123

  • I Don't Know What To Do
  • SF V.I.P
  • ********
  • Posts: 5818
  • Reputation: 65534
  • Gender: Male
  • Ficticious Boy
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #787 on: June 07, 2011, 01:37:54 pm »
guys
do we have to learn the frequencies and wavelenghts of colrs of light?
like red, yellow... etc.?

that is simple

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #788 on: June 07, 2011, 01:40:03 pm »
guys
do we have to learn the frequencies and wavelenghts of colrs of light?
like red, yellow... etc.?


It's better to know the whole EM spectrum.
divine intervention!

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #789 on: June 07, 2011, 01:43:02 pm »
Can someone please help me out with q 37
http://www.xtremepapers.me/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_s08_qp_1.pdf

COmbined resistance of VOltmeter and R2 = 50ohms
VOltage that part receives = 50/150 * 6 = 2V

Current = V/R = 2/100000 = 20*10^-6
divine intervention!

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #790 on: June 07, 2011, 01:43:43 pm »
Quote from: JACKRABBIT



WOW thanks man....ur good lol

AALSO...I know that a electric field with the positive plate earthed will still have a positive chargeon it...but what if a theres an electric field and the NEGATIVE plate is earthed??? will there still be a negative charge on it??? or will there be no charge on it...??

I'm not sure about this, but I think it won't have a charge on it if the -ve plate is earthed.
divine intervention!

Offline wstrawberries

  • SF Immigrant
  • **
  • Posts: 54
  • Reputation: 66
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #791 on: June 07, 2011, 02:35:48 pm »
COmbined resistance of VOltmeter and R2 = 50ohms
VOltage that part receives = 50/150 * 6 = 2V

Current = V/R = 2/100000 = 20*10^-6


Thank you :)

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #792 on: June 07, 2011, 03:19:41 pm »
w03_qp1 Question 16

Doubt : How is the force H at the hinge greater than the Weight?
divine intervention!

Offline EMO123

  • I Don't Know What To Do
  • SF V.I.P
  • ********
  • Posts: 5818
  • Reputation: 65534
  • Gender: Male
  • Ficticious Boy
Re: ALL CIE PHYSICS DOUBTS HERE !!!
« Reply #793 on: June 07, 2011, 03:32:54 pm »
w03_qp1 Question 16

Doubt : How is the force H at the hinge greater than the Weight?
in this see the forces applied

on W it is the least because it is simple to make it fall the door down

then it is H as to open the door from hinge needs more force

and the last is the T with the highest force because of the weight of the door
hope it helps