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Physics: Post your doubts here!

ahmed abdulla

ahmed abdulla

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1__Two springs P and Q both obey Hooke’s law. They have spring constants 2k and k respectively.
The springs are stretched, separately, by a force that is gradually increased from zero up to a
certain maximum value, the same for each spring. The work done in stretching spring P is WP,
and the work done in stretching spring Q is WQ.
How is WP related to WQ?
A WP =  1/4 WQ B WP =1/2  WQ C WP = 2WQ D WP = 4WQ
i get C ... but the answer is B


2___A wave of amplitude a has an intensity of 3.0Wm–2.
What is the intensity of a wave of the same frequency that has an amplitude 2a
A_12 .. i used I>A^2 and still not coming​
 
Tkp

Tkp

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adibshamsuddin said:
M/J/12 paper 12 questrion no 30. If anyone can help, I would be very obliged.
Click to expand...
see the cro rises to a maximum at a position X, falls to a minimum and then rises once again to a maximum at a
position Y. so the distance between the adjacent antinodes is .5lambda
so 33*2/100=lambda
v=flambda
and f is 500
so the time base for 1 div is .5ms
so it takes 4 div to complete a wave that means 4*.5
=2 ms
2/1000=1/500
and f=1/t
so it matches and the ans is B
Hope ur clear nw
 
B

beeloooo

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XPFMember said:
Hi everyone, AsSalamoAlaikum Wr Wb...

To get things organized in a better way, I am making this thread. As othewise, some queries remain unanswered!

So post your PHYSICS doubts in this thread. InshaAllah other people here will help me and you all. :D ;)

NOTE: If any doubts in the pastpapers, please post the link! You can find links here!

Any Physics related notes and links will be added here in this post. Feel free to provide the links to your notes around the forum, or any other websites! :)
Thanks!
Jazak Allah Khair!

Physics Notes:

Some links & Notes - by destined007

As physics p1 MCQS YEARLY Solved [explaination]
Physics Practical Tips - by arlery

Notes for A2 Direct Sensing (Applications) - shared by sweetiepie

Physics Summarised Notes (Click to download)

AS and A-Level Physics Definitions

A2: Physics Revision notes - by smzimran

Paper:5 Finding uncerainty in log - by XPFMember

Physics Paper 5 tips - by arlery

Physics Compiled Pastpapers: <Credits to CaptainDanger for sharing this..>

Here are the compiled A level topical Physics questions in PDF form...

Paper 1 : http://www.mediafire.com/?tocg6ha6ihkwd

Paper 2 & Paper 4 : http://www.mediafire.com/?g65j51stacmy33c

(Source : http://www.alevelforum.com/viewtopic.php?f=15&t=14)
Click to expand...
The physics p1 topical dont they have the answers with them ? please be kind to reply.
 
R

raamish

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Tkp said:
see the cro rises to a maximum at a position X, falls to a minimum and then rises once again to a maximum at a
position Y. so the distance between the adjacent antinodes is .5lambda
so 33*2/100=lambda
v=flambda
and f is 500
so the time base for 1 div is .5ms
so it takes 4 div to complete a wave that means 4*.5
=2 ms
2/1000=1/500
and f=1/t
so it matches and the ans is B
Hope ur clear nw
Click to expand...

hey in n07 to measure pressure we are using pressure gauge. it's saying not allow pressure meter or barometer. so in calculating pressure do we always use pressure gauge or sometimes pressure meter or barometer can be used. and in mark scheme there is a pt written difficulty in measuring amplitudes at small pressures. Use a large incident source. So i wrote that use high values of p so that a could be measures easily. So can u explain this mark scheme point. And another point that the window should be perpendicular to source. Should we write this point whenever something is being transmitted through a substance? And what is the purpose of the pt. these are a lot of questions sorry but plzz help :)
 
Y

Yousif Mukkhtar

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h4rriet said:
7. The component of acceleration is the acceleration due to gravity and that's the same always anywhere on Earth.
20. Choose a point and find the pressure due to P & Q at that same point. For example, any point on the second dotted line. The pressure due to Q will be = density of Q x g x h. The pressure due to P will be = density of Q x g x 2h. Cancel out g for both, you'll get density of Q = pressure/h, and density of P = pressure/2h.
25. Points on a wave vibrate up and down, and don't move to the right. A trough is travelling towards P, so P is going down.
Click to expand...

THank you alot for the help.
 
gary221

gary221

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gary221

gary221

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Yousif Mukkhtar said:
Can some one please help

Q37,40
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s07_qp_1.pdf
Click to expand...


40) It is the q/m ratio that is important, and this has the lowest value for the lithium nucleus. ← given in the examiner report.
So, u have to calculate the charge to mass ratio, whichever is the lowest will have the least acceleration.
q/m ratio of hydrogen = 1/1 = 1
q/m ratio of helium = 2/4 = 0.5
q/m ratio of lithium = 3/7 = 0.42
q/m ratio of beryllium = 4/9 = 0.44

lowest ratio is that of lithium, hence that will have the lowest acceleration.

37) Not sure about this, but i think that since the volume of the two pieces are equal, their resistances will also be equal.

Hope u gt it!
All credit to Nibz
 
syed1995

syed1995

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zackle09 said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s09_qp_1.pdf

in questions like the one in number 6...how are you supposed to know when to convert voltage to V or leave it as mV? sometimes they do it and sometimes they dont :/
Click to expand...

What's the formula for Power? P=IV

you need to work in the same units.. so convert the V reading from mV to V (THAT'S the best thing to do in every question).

they should be both in their standard form which will give you power in terms of standard watts... (As the final answer is in watts)

SO ALWAYS CONVERT IT INTO STANDARD UNITS before doing the calculations..

1200mV = 1.2V
0.48A

P=IV
P=1.2*0.48
P=0.576

so answer is B.
 
Z

zackle09

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syed1995 said:
What's the formula for Power? P=IV

you need to work in the same units.. so convert the V reading from mV to V (THAT'S the best thing to do in every question).

they should be both in their standard form which will give you power in terms of standard watts... (As the final answer is in watts)

SO ALWAYS CONVERT IT INTO STANDARD UNITS before doing the calculations..

1200mV = 1.2V
0.48A

P=IV
P=1.2*0.48
P=0.576

so answer is B.
Click to expand...

Okayy got it! thanks alotttt :D
 
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