Physics: Post your doubts here!

[Mohammed salik]

Gr8..! I actually Only needed this !
Thnx Man

Mohammed salik
Dont wanna explain.Yahin samjh jaogay

 

[usama321]

I'm sorry but I tried doing the first part ..
The thing I don't get is .. Why don't u take the ENTIRE area under the graph ... As in we took .5 *9*2.4 okhay understood ..
Then why not L *B ?
Y do we take 1/2 *6*1.6 only?
And lastly, why do we subtract them ? :$

It is a triangle not a square or a rectangle xD Area of triangle is 1/2 base * height. Once the velocity is in negative, the ball is coming back downwards. Now, the question asks the distance from the ground to the hill, where the ball is now resting. The ball reached its highest point (v = 0 here) then started coming back downwards (v in negative here) and stopped at a hill. Thus the areas are subtracted

 

[_Ahmad]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s13_qp_23.pdf

can anyone PLEASE explain Q5 b iii)

 

[usama321]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s13_qp_23.pdf

can anyone PLEASE explain Q5 b iii)

-__- Zepudee solved it for you on the previous page

 

[robinhoodmustafa]

Han kafi gand tha Kafi der lag gai thi solve kerte hue

Do u have the David Sang wali book?
I have to ask a small same question from it.

 

[usama321]

Do u have the David Sang wali book?
I have to ask a small same question from it.

Yup i have it

 

[robinhoodmustafa]

Please help me.
This a question from Mj 2004 and It says to draw a wave on the same diagram with double the intensity and 180 Phase difference but I am cofused with the (o.2,0.4) how can I know about the angles meaning Interpret these points on x axis as angles.. Hope you know what meant to say.
But do help me

 

[kathy nelson]

ASA
Can someone help me with this?
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_qp_2.pdf
Question 5 part b
Thanks in advance

 

[robinhoodmustafa]

Please help me.
This a question from Mj 2004 and It says to draw a wave on the same diagram with double the intensity and 180 Phase difference but I am cofused with the (o.2,0.4) how can I know about the angles meaning Interpret these points on x axis as angles.. Hope you know what meant to say.
But do help me
View attachment 42208

 

[robinhoodmustafa]

ASA
Can someone help me with this?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s09_qp_2.pdf
Question 5 part b
Thanks in advance

usama321
Hehe again this question

 

[robinhoodmustafa]

Yup i have it

Page 225
TestYourself Q12

 

[usama321]

Please help me.
This a question from Mj 2004 and It says to draw a wave on the same diagram with double the intensity and 180 Phase difference but I am cofused with the (o.2,0.4) how can I know about the angles meaning Interpret these points on x axis as angles.. Hope you know what meant to say.
But do help me
View attachment 42208

We know that a full wave has 360 degrees. 180 would be half of it. Furthermore, we also know that 180 means destructive interference which pretty much explains the whole question

 

[usama321]

Page 225
TestYourself Q12

For 12 a use d sin theeta = 2 lamda
for 12 b use d sin 90 = n lamda

 

[Haya Ahmed]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s06_qp_2.pdf

Q5 c can someone explain ! thanks ^^


and

Q7 (a) what do you mean by lamp is shortened

 

[Snow Angel]

t

at maximum point, the crest and crest meet: so displacement = 1.4+2=3.4 units
at minumum point crest and trough meet so displacement = 2-1.4=0.6
I is directly proportional to a²
so ratio of I = 3.4²:0.6² = 32.1
Snow Angel

thnx can u plz explain q 5 aii) from: papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_22.pdf

why is it I1R2/2 and I2R2/2???

THNX IN ADVANCE. if u don mind me askin, which variant r u writing for all ur papers?

 

[zem]

B (i)

You can calculate the area by Box Counting method.
Find the area of an individual box between the two curve. Highlight small size boxes and multiply the total with the area of 1 box.

or another method is to assume the curve to be straight and apply the triangle area formula but I am not sure in this whether they have given a range in MS.
edit:
I found a useful site which shows a similar problem and he has assumed the curve to triangle.
http://tap.iop.org/mechanics/materials/229/page_46534.html
scroll down . and read the heading "Energy stored in stretched material"
because it said as long the object obeys hookes law than it is considered as a triangle. because u see the unloading part on question shows that it returns back to its orignal length

thanks alot!

 

[robinhoodmustafa]

We know that a full wave has 360 degrees. 180 would be half of it. Furthermore, we also know that 180 means destructive interference which pretty much explains the whole question

i know that but How do I Interpret that at this point the second and first wave has a PD of 180.
Like Turn 0.2,0.3,0.4 etc in angles* So that i may find it easy to locate 180 on the graph. That is what i am trying to say

further more..
If intensity is doubles than It means that Amp is 4 times increased ..right? *read the question*

btw Hey! I see my Name *imFamous*

 

[robinhoodmustafa]

For 12 a use d sin theeta = 2 lamda
for 12 b use d sin 90 = n lamda

The Calculating no of minima and maxima wala.

How did do know it would be sin teeta = 2 lamda.. is it written anywhere

 

[usama321]

i know that but How do I Interpret that at this point the second and first wave has a PD of 180.
Like Turn 0.2,0.3,0.4 etc in angles* So that i may find it easy to locate 180 on the graph. That is what i am trying to say

further more..
If intensity is doubles than It means that Amp is 4 times increased ..right? *read the question*

btw Hey! I see my Name *imFamous*

180 Phase difference equals one half of a wave. Just for your convenience, start the other wave after the half of the first wave, and then extend it to either sides. You will understand.
I = A^2 Amplitude here is 5. Put in the values get the amplitude double it and underroot

The Calculating no of minima and maxima wala.

How did do know it would be sin teeta = 2 lamda.. is it written anywhere

It says the second order.... second means 2 And we put in sin 90 to calculate the maximum number of orders. The light can't diffract more than 90 of course (according to my knowledge ) and thus when we put in 90 we get a decimal value of something around 5.7... Thus our answer would be 5

 

[Autumngirl]

I am confused about significant figures in paper 2. I've always been told to give as many significant figures in the answer as the least number in the data provided e.g. If data has both 2 and 3 significant figures, the answer must have 2 as it's the number in the least precise data. However, in the papers the mark scheme doesn't always follow this rule. Check out MJ11p23 question 3. Can somebody please explain why the examiners do this and give me a perfect rule about significant figures? Thank you!