Physics: Post your doubts here!

[syed1995]

f=qe(1.2*10^-15*2*10^3)

I still don't get it. :\

 

[Tkp]

I still don't get it. :\

i hope u knw the formula
force=electric field strength multiplies charege
charge is given and we calculated the electric field strength
find out the force

 

[yousef]

for the sound at m to be zero that means destructive interference.so for destructive interference the path difference must be be a odd number of multiple wavelength
and for the second conditon if the amplitudes are same so there will be destructive interference as the two waves cancel out each other
so for the first 1 it would be the path difference must be be a odd number of multiple wavelength and 2 nd one amplitude amplitude of both the waves are same at m.
b)v=f lambda.so u put these values and u get 2 value of l(convert the unit in cm).that means the minima would be within the range.now find the path differnce.find the length of s2m by pythagoras theorem which is 128 cm.so the path difference for s2m-s1m is 28 cm.now apply the formula of path difference for destructive interference
28=(n+.5)l put the value of n to o,1,2,3,4.now u will get 2 values which are within the range.so 2 minima would be detected

thannsk bro ... i understood everything ... but my question is ... at the begining how did u now its (destructive interfernce ) and not constructive ???
and can u plz post the( formula _) for path difference of constructive and destrcutive interfernce separetly ?

 

[Tkp]

thannsk bro ... i understood everything ... but my question is ... at the begining how did u now its (destructive interfernce ) and not constructive ???
and can u plz post the( formula _) for path difference of constructive and destrcutive interfernce separetly ?

i think u didnt read the question properly.they told to determine the number of minima which is destructive intereference and maxima is constructive interference
Path difference of constructive interference =nlambda
Path difference of destructive intereference =(n+.5)lambda
hope u are clear

 

[snowbrood]

np mate! do it in a couple hours .. aaj hamaray yahan tu nai gayi light... (cuz of sunday) where you from?

i am from hyderabad

 

[aniroula]

may/ june 2012 paper 52 qno 2(b). How to find the uncertainty in the value of (1/L)..??

 

[Ahmad Zaeem]

M/J 2008 Q 14 and 16.....Concept plsssss!!!!!!!....

http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s08_qp_1.pdf

 

[Tkp]

M/J 2008 Q 14 and 16.....Concept plsssss!!!!!!!....

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s08_qp_1.pdf

for no. 14 anticlockwise moment equals to clockwise moment
so clockwise moment is wa +fh
anticlockwise moment is w*2a
so ans is wa+fh=2wa
for potential energy, vertical height is always taken, so distance would be s.
The field is towards the right side, so left is positive and the right negative, which means that the potential energy will decrease. energy = workdone, therefore, w.d. = F x s

 

[Silent Hunter]

Any useful notes for the applications part ... especially the last chapter (communications one) ?

JazakAllah

 

[syed1995]

Tkp , snowbrood and everyone else

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s11_qp_12.pdf

Question 7 .. why and how D.. why not C?

 

[Malik777]

http://papers.xtremepapers.com/CIE/...A and AS Level/Physics (9702)/9702_w12_gt.pdf How AS max marks 130? :O

 

[Malik777]

Tkp , snowbrood and everyone else

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_12.pdf

Question 7 .. why and how D.. why not C?

As this is velocity time graph, so according to Displacement time graph the amplitude has velosity zero m/s & in this graph at 0 m/s the displacement will be maximum

 

[Tkp]

Tkp , snowbrood and everyone else

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_12.pdf

Question 7 .. why and how D.. why not C?

maximum displacement means velocity 0.check velocity is point 0 at 5 and 15 and at point q the particle is stationary.so the accleration at q is zero

 

[Omar99]

plz helpme
http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w11_qp_42.pdf
can u tell me how to do question no. 3 part bii,
question on. 7 part c
an question no. 9 part c

 

[Omar99]

as we know that frequency of fundamental is f
frequency of second harmonic is 3f
and that of third harmonic is 5f
u have to memorize it
page no 237 chemistry coursebook cie

can u tell me why is this not an open pipe, so we can use the other
formula

 

[jsg]

http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_w06_qp_6.pdf

Question number 15 part b (i) where we have to find the bandwidth.

 

[Omar99]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_13.pdf
Question no. 40
And 11

 

[Tkp]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_13.pdf
Question no. 40
And 11

for no. 40 nucleus x is emitting an alpha particle so 84-2=82
then it gains two beta particles so 82+2=84

 

[farhan143]

Can anyone tell me what is Newton's Third Law..
The correct one..
Thanks in advance

 

[hino]

Can anyone tell me what is Newton's Third Law..
The correct one..
Thanks in advance

'When 2 bodies interact,force on one body is equal in magnitude but opposite in direction to the force on the other body'
Below are the points for a 3 marks definition of newtons 3rd law from the marking schemes
'force on body A is equal in magnitude to force on body B (from A)
forces are in oppositre directions
forces are of the same kind'