Physics: Post your doubts here!

[unique111]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s13_qp_22.pdf

Question 5b iii

 

[doremon]

but I am not getting the answer

change in gravitational potential energy = 3.8*1.5*10^-2(because extension is in centimetre)

 

[Haya Ahmed]

now use the cosine rule. angle is 90+45. scale drawing will not give accurate result because the velocity of wind gives 1.8cm only if i took 1 cm = 20 m/s

But the question didn't ask for drawing such diagrams ! I did this way and got the answer ! but I'm not sure did this answer 1 e (i) or not ! please someone correct me If I'm wrong !

Suchal Riaz

 

[_Ahmad]

change in gravitational potential energy = 3.8*1.5

What about the second part (2.)

 

[Snow Angel]

srry

Snow Angel
question number 4 (b) (iv)
current = 0.24 A
(a) p.d = IR = 0.24*5.5=1.32V
(b) terminal p.d = emf - lost volts = 4.4 V - (0.24 A * 2.3 ohm) = 0.552 V
(c) terminal p.d = emf - lost volts = 2.1 V - (1.8 ohm * 0.24 A) = 1.67 V

can u plz explain

why do they add the emf and the lost volts to find the terminal pd of cell B the answer is 2.1+(1.8*0.24)=2.53

 

[Suchal Riaz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_23.pdf
Q 1 e both i and ii
and Question 2 a ii

acceleration = gsin15
AB = 0.26/sin15=1.0
s=ut + 1/2 at² as u=0, s=1/2 at²
√(2s/a)=t
t= √( ( 2*1 )/ gsin15) = 0.89s

 

[Suchal Riaz]

IS THIS OK?

yes

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s13_qp_22.pdf

Question 5b iii

if you see the the fig 5.2 you will realize the total wave produce are 3/2
so length 3/2 lamda

 

[doremon]

What about the second part (2.)

use the formula E=1/2*k*(x^2)

 

[_Ahmad]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w09_qp_22.pdf
Can anyone PLEASE explain Q4 c ii) full

 

[Suchal Riaz]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s13_qp_22.pdf

guys how are we suppose to do q 5part b iii i dont get how we r suppose to draw the new wave

new wave will be straight line.
Haya Ahmed please give him the pictures and animation which i gave you yesterday and explain it to him how i explained it to you. i have to solve many other doubts.

 

[doremon]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_22.pdf
Can anyone PLEASE explain Q4 c ii) full

I just did fag -_-

 

[_Ahmad]

use the formula E=1/2*k*(x^2)

sorry dude if I am bothering you too much
can you please explain it

 

[doremon]

sorry dude if I am bothering you too much
can you please explain it

you do know the formula for elastic potential energy, right?

 

[Suchal Riaz]

c

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_22.pdf
Can anyone PLEASE explain Q4 c ii) full

Change in U = mgh = 2.8N * 0.015 m = 0.057J
change in e.pe = e.p.e in 16.3 cm extension - e.p.e in 17.8 extension
=1/2k(e1²-e2²)
the k we found was in N/cm not in N/m we we will convert it. we get k=180N/M
1/2 * 180 * (0.036²-0.021²)=0.077J

 

[kitkat <3 :P]

M sorry for my terrible writing JAVERIA INAM DANISH

 

[Haya Ahmed]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_23.pdf

Q1 e is the asnwer right ??????????? for part e i and eii together ??

 

[IGCSE13]

I

Here you need to draw labelled diagram of source of light, apparatus to diffract/interfere and how to observe it.
To observe the diffraction the light must be perpendicular to the slit and the screen must be long distance from slit
to observe. we will decrease slit separation(in (ii) ) and slit width in (i) part.
(i) when we will decrease it, the the spot will start to spread into geometric shadows. along the bright big spot a few fringes will also be observed but they will be dim.
(ii) the fringe seperation will increase. alternate bright and dark fringes will be produced.

Idon't get how does this represent diffraction

 

[Suchal Riaz]

But the question didn't ask for drawing such diagrams ! I did this way and got the answer ! but I'm not sure did this answer 1 e (i) or not ! please someone correct me If I'm wrong !

Suchal Riaz

correct. but i drew it to make it easy for you to understand. i always use cosine rule or Pythagoras theorem unless examiner himself says to draw scale drawing.
i also said at the end to use cosine rule. that diagram was for concept.

 

[Suchal Riaz]

I

Idon't get how does this represent diffraction

the laser is normal to a slit and that difracted light goes to screen. right click that image and open it in new tab because the image is rotated in this website.