Physics: Post your doubts here!

[Pasindu]

Assalamoalaikum wr wb!!

Nov 2003

· Q:5 b (ii) need explanation, I don’t get it... :s​

· Q:4 c Can you show, how is the less ripple represented, please.. :s​

· Q:2 b (ii) –ve sign?​

​

Q5 B ii - I think because Tesla is the magnetic flux density acting normal to the object in this case because they
are parallel if you try resolving MFD normal to the object then it is MFD x cos 90 , which is equal to zero
the answer is change is = 9.81 x 10 ^-5

Q 2 ii - acceleration and displacement are vectors therefore minus is used to show that accelaration is always opposite to the direction of the displacement and W is squared is to ensure that constant is always positive.

 

[Pasindu]

Assalamoalaikum wr wb!!

​

Nov 2006

· Q:3 c what to write? :s​

· Q:4 b ans. Is 5.99 x 10^24 how does ms say 6.00 :s​

· Q:5 a (ii) what’s eddy current?​

What is eddy current this was help full to me

It is the current induced in the conductor when there is a changing magnetic field

Hope This is helpful

 

[Pasindu]

Got a doubt in O/N 2010 paper 43, question 3a(i). how do we find the displacement??...i mean there's no value given for "t" in the given equation!!

O/N 2010 paper 43, question 3a(i)

d = -4.0 x cos ( 220 t)
W= 2 x pi x f and W=220
then f = 35
then f = 1/ t
then t = 1/35
Substitute and get the answer i think this is the way

 

[Pasindu]

and sorry it is modulus of elasticity

it's this in maths and not in physics

 

[Pasindu]

i have another doubt it is 4rm 2004 may/june paper 2 Q1_b
View attachment 4627

the drawing part is my weakness
i dont know where to draw the two lines can anyone draw the diagram and post it back thank you!

Resultant is = [ 8 cos 20 ] x [ 6 cos 20 ] = 13.2

 

[smzimran]

smart then...
i cant figure it out

Check the position of the piston at A, the piston cant go further down, so that is why it is max. displacement!
For the rest,
I see SkyPilotage already answered!

 

[smzimran]

Thanks A lot Bro

JazzakAllah

yup...I do it's easy....say you are taking log of x...

now x is suppose.. 83 +/- 5...
log 83 = 1.92
so Upper Limit (UL) = 83 + 5 = 88
and lower limit (LL) = 83 - 5 = 78
find log of (UL-LL)/2 = (88-78)/2 = 5
log 5 = 0.70 => This is the uncertainty...
so log(83 +/- 5) = 1.92 +/- 0.70
Hope this helped..!

There is a problem here
http://www.xtremepapers.com/community/threads/physics-paper-5-tips.12941/#post-190711
See here!

MODERATOR EDIT: Posts have been removed due to some error made in that...please check the link above to find out how to find uncertainty in log.

 

[hassanfarooq92]

need some help in winter 2010, paper 41 question # 2, help required in completing the table........

 

[Zishi]

need some help in winter 2010, paper 41 question # 2, help required in completing the table........

You'll get more and quick replies if you take a screen shot of the question and attach it over here. . .

 

[rodent123]

too many problems, and since THIS time I am attaching the questions please answer people!
M\J 2010 paper 42 Q5 part b part 2
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_42.pdf

 

[rodent123]

another one now
M\J 2010 42 Q7 part b part 3. I don't get it where does the frequency comes from and how?? and also question 10 of the same paper part b, explain the drawing please!
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s10_qp_42.pdf

 

[rodent123]

acha moving on O\N2010 Q1 part c part 2. Why don't we place "Re" in denominator of earths radius? why "x2"(the 2 over here means square since I don't know how to do that superscript thingy) please also check Q2 part b part2 of the same paper can somebody please explain me the table? I am unable to comprehend the markscheme and question
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_41.pdf

 

[rodent123]

O\N 2010 41 QUESTION 7 .Didn't get the whole question
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_w10_qp_41.pdf

 

[SkyPilotage]

too many problems, and since THIS time I am attaching the questions please answer people!
M\J 2010 paper 42 Q5 part b part 2
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_42.pdf

Capacitance Ratio is 1 : 2 and each capacitor can hold 6 volt max.
3 Volts 6 Volts
Total = 9 Volts maximum

another one now
M\J 2010 42 Q7 part b part 3. I don't get it where does the frequency comes from and how?? and also question 10 of the same paper part b, explain the drawing please!
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_42.pdf

formula is V= Vmaxsin(omega t)
omega= 2pie f
120pie = 2pie f
f = 120pie/2pie = 60Hz

will solve question 10 later and scan it for you

acha moving on O\N2010 Q1 part c part 2. Why don't we place "Re" in denominator of earths radius? why "x2"(the 2 over here means square since I don't know how to do that superscript thingy) please also check Q2 part b part2 of the same paper can somebody please explain me the table? I am unable to comprehend the markscheme and question
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_41.pdf

Because we are using graviatational fields in solving the question. We equate g of Earth = g of Moon with formula GM/x^2.
If you need help solving it tell me and Ill take a photo of it for you.

 

[Unicorn]

For question no. 15
Since the water will be equally divided in both the vessels after the tap is opened so vessel X will now have h/2 height of water and m/2 mass of water.
Due to which potential energy lost= (m/2)*(g)*(h/2).
So, final answer will be (mgh)/4. Hence no. B

ohhh i forgot about the mass that is why
thanks ^^

 

[JD REBORN]

Q 1 why is the answer C,it should be B?

 

[Unicorn]

Re: Physics Help here! Stuck somewhere?? Ask here!

I'm having a little doubt in vector components. Consider this: A trolley of weight, W, 600 N is going down a slope, which is at an angle of 30* to the horizontal. They say that the component of W down the slope is = W sin 30*. How is that? The way I'm thinking it should be W/sin 30*. I'm obviously wrong. Can anyone explain why?
Thank you.

whenever you have an inclined plane always resolve the weight like shown

now look at the angle theta between the weight and the resolved component this is corresponding to the angle of the plane which is 30

to get the horizontal component above the plane you use Wsin30 because if you re arrange the forces and take the horizontal one and place it above 600N force (which will be the hypnoteuse) and other component you get a triangle and to get that side of the triangle you have to use sin

hope it helped

 

[SkyPilotage]

Q 1 why is the answer C,it should be B?

Someone needs to revise his prefixes
nano is 10^-9 not ^-6
(3x10^8)/(600x10^-9) = C

 

[JD REBORN]

Someone needs to revise his prefixes
nano is 10^-9 not ^-6
(3x10^8)/(600x10^-9) = C

I dont understand what expression u have used,i mean u have divided speed of light with wavelength??

 

[JD REBORN]

In Q 15 why arent B and C correct,in Q30 why isnt B correct,in Q36 why cant A be correct and Q 39?