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Physics: Post your doubts here!

goodluckayesha

goodluckayesha

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syed1995 said:
Extension is directly propotional to force..

let the Force needed to get extension x be F..

So horizontal component of S1 = Fcos60
same with S2 FCos60

FCos60+FCos60 = F .. so the extension of S3 would be x.. what's the answer?
Click to expand...
the answer is correct n thnq u soo much for the explanation but the mark scheme says
" same force F in both springs
resultant is 2F cos60 or scale drawing
resultant F so extension is x (maximum 1/3 marks if x is used alone without reference to kx)"
this red part wht wud b use of kx???
 
syed1995

syed1995

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goodluckayesha said:
the answer is correct n thnq u soo much for the explanation but the mark scheme says
" same force F in both springs
resultant is 2F cos60 or scale drawing
resultant F so extension is x (maximum 1/3 marks if x is used alone without reference to kx)"
this red part wht wud b use of kx???
Click to expand...

Yea.. you need to give the refrence.. that since F is directly proportional to extension .. the extension will be same... F=kx where k is constant... I just solved the question .. that depends on the marks of the question ...
 
goodluckayesha

goodluckayesha

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syed1995 said:
Yea.. you need to give the refrence.. that since F is directly proportional to extension .. the extension will be same... F=kx where k is constant... I just solved the question .. that depends on the marks of the question ...
Click to expand...
it was for 3 marks hmm I got it :)
thnq so much.....
 
Ariel Robert

Ariel Robert

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Warrior66 said:
i think the answer's D?? (obviously you need to write the actual answer as well in order for me to know if i have got it right and only then would it make sense that i explain how i got it..)
Click to expand...

Bro, The full question is wrong or one of the options are missing...
 
gary221

gary221

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Sapphires said:
I need help with Questions 4b and 4d, plz. Thank you.
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_41.pdf
Click to expand...

4b i) field strength is (negative of) potential gradient (see coursebk, pg 349)
ii) Field strength is proportional to force on Q --> as E = F/q
potential gradient proportional to gradient of (potential energy) graph ---> as potential = potential energy/mass
So, since field strength is (negative of) potential gradient
It implies that filed strength is also proportional to gradient of the graph.

Hope u gt it!!
:)
 
gary221

gary221

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4 d i) As v can see in the graph, when distance x increases, potential energy bcoms more positive ie potential energy also increases.
This implies that work is done in separating the charges ----> ie the 2 charges r actually attracting each other ---> so they both r oppositely charged!

ii) Doubling the charge on P will mean more work will need to be done to separate the 2 charges ie potential energy will also double.
So, the graph will be steeper n the gradient will increase..

Sapphires...Hope u gt it!
 
Sapphires

Sapphires

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gary221 said:
4 d i) As v can see in the graph, when distance x increases, potential energy bcoms more positive ie potential energy also increases.
This implies that work is done in separating the charges ----> ie the 2 charges r actually attracting each other ---> so they both r oppositely charged!

ii) Doubling the charge on P will mean more work will need to be done to separate the 2 charges ie potential energy will also double.
So, the graph will be steeper n the gradient will increase..

Sapphires...Hope u gt it!
Click to expand...
Thank you! This helped so much!
:)
 
ruler_of_the_world

ruler_of_the_world

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think abt it this way. As u increase the width u let in more light thus at the point previously where u had constructive interference, over there now more waves will coincide due to the widening of the gaps. Thus the brightness increase.
 
gary221

gary221

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minie23 said:
6(d)
Click to expand...

when m is 1st released, the strain energy in the spring (or the elastic potential energy) is converted to kinetic energy(so results in movement of M) + potential energy due 2 gravity, as M is pulled down due to gravity.
then it reaches S, stretching is max, after which the extension reduces ---> pulling up M again ie height increases.

Hope u gt it!
 
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