Physics: Post your doubts here!

[RAMEEZA]

http://lightandmatter.com/html_books/lm/ch13/ch13.html

thanks for the link....it helped a lot

 

[Dr Death]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s12_qp_12.pdf
And in question 22, why don't we find the denisty of a single atom?

It is not required. Just get the volume (of whole square) and cube root it.

 

[princess Anu]

J13,P21
Q1(a), why does the marking scheme say' The wire returns to its original length and not shape.. Why not shape?
5 a Why is it important for the waves to be unpolarised or have same direction of polarisation?
5d what will be the difference in the effect of reducing the gap between the slits and making them narrower?
3a Why can't we mention here about the ball reachint terminal velocity and then the conversion of GPE to Thermal energy only?
4c how do we know if the temperature is kept constant for the gas? :/ ( this is the answer given in the Marking scheme)


Please Do answer!
Jazak Allah

 

[amal sharkawi]

 

[princess Anu]

X and Y have equal amplitude and displacement no? :/

 

[The Godfather]

X and Y have equal amplitude and displacement no? :/View attachment 51330

Amplutidue = Maxm displacement. Here x and y are not at its maxm displacemets so it is not the same amplitudes but the same displacements. And answer should be B because wavelengeth is the smallest distance b/w two consecutive crest or through.
Do temme if m wrong.

 

[The Godfather]

J13,P21
Q1(a), why does the marking scheme say' The wire returns to its original length and not shape.. Why not shape?
5 a Why is it important for the waves to be unpolarised or have same direction of polarisation?
5d what will be the difference in the effect of reducing the gap between the slits and making them narrower?
3a Why can't we mention here about the ball reachint terminal velocity and then the conversion of GPE to Thermal energy only?
4c how do we know if the temperature is kept constant for the gas? :/ ( this is the answer given in the Marking scheme)


Please Do answer!
Jazak Allah

1a) You should prefer the word length instead shape. As its defination says extended elasctisity is when the load is removed the material should gain its orignal length.
5) Yet not done in our syllabus. Sorry.
3a)Question asks for energy conversions, "State and explain the energy conversions that occur as the object falls."
4c)K.E is directly proportional to the temprature.

 

[Mahnoorfatima]

It is not required. Just get the volume (of whole square) and cube root it.

But why not? I don't get that we are supposed to find the value of a single atom so why do we conside rthe density of the whole crystal??

 

[Mahnoorfatima]

check at
http://physics-ref.blogspot.com/2014/06/9702-june-2012-paper-12-worked.html

There's no paper of MJ11 paper 13??

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w11_qp_12.pdf
I don't get this question!!! question 14. WHY are we taking the back wheel specifically as the pivot? Why can't we take X as the pivot since the weight is hitched to the cab at X????

 

[The Godfather]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_12.pdf
I don't get this question!!! question 14. WHY are we taking the back wheel specifically as the pivot? Why can't we take X as the pivot since the weight is hitched to the cab at X????

You can consider about any point unles they have asked you to consider any point as pivot.
Read the question "What is the upward force exerted by the cab on the trailer at X?"
Pivot is taken as the end of trailor and then since resultant moment =0,y is taken as the force we need to find
anticlockwise=clockwise
y x 20m=30000N x 20
so y(force)=15000N

 

[Mahnoorfatima]

You can consider about any point unles they have asked you to consider any point as pivot.
Read the question "What is the upward force exerted by the cab on the trailer at X?"
Pivot is taken as the end of trailor and then since resultant moment =0,y is taken as the force we need to find
anticlockwise=clockwise
y x 20m=30000N x 20
so y(force)=15000N

Of the same paper can you check question 38? I don't get why do we use the potential divider equ and WHEN do we need to use it??

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w11_qp_11.pdf
Question 6 ,20, 38 any one? ;/

 

[manya]

can someone explain y the right answer is not C instead of B

 

[Dr Death]

can someone explain y the right answer is not C instead of B

No Kinetic energy is lost in a perfectly elastic collision

Therefore Speed of approach = Speed of projection

Momentum AND total energy is ALWAYS conserved

 

[Mahnoorfatima]

check at
http://physics-ref.blogspot.com/2014/06/9702-june-2012-paper-12-worked.html

Why don't you have the paper 11's or 13's of 2012 and backwards? :/ Where am i supposed to find those?

 

[Dr Death]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_11.pdf
Question 6 ,20, 38 any one? ;/

When ball is sliding down the slope then as there is acceleration, velocity is increasing (first part of graph).
When ball is going on horizontal surface, constant velocity.
When ball collides with wall then direction of velocity is changed.
As inelastic K.E is lost.
Velocity is lost.
Ball slides a small way up before stopping

 

[Mahnoorfatima]

When ball is sliding down the slope then as there is acceleration, velocity is increasing (first part of graph).
When ball is going on horizontal surface, constant velocity.
When ball collides with wall then direction of velocity is changed.
As inelastic K.E is lost.
Velocity is lost.
Ball slides a small way up before stopping
View attachment 51353

Then what's the difference in the other options?

 

[Mahnoorfatima]

check at
http://physics-ref.blogspot.com/2014/08/9702-november-2011-paper-12-worked.html

I did but what i don't get is when do we need to use this equation. Is there a specific cricuit in which this potential divider equ is used ?

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_11.pdf
In q 24 why is A wrong???
And I DONT get question 28!