Physics: Post your doubts here!

[Hemdon]

Well here as I would have answered it : Consider a gas enclosed in a cylinder. The gas molecules move randomly throughout the cylinder and collide with the walls of the cylinder, thereby exerting a force on the cylinder. As pressure is defined as the force acting normally per unit area, upon collisions, the molecules exert a pressure on the walls of the cylinder.

Still, if anyone else has a suggestion, please notify. Hope this helps

Thanks, u made me relieved....o and if i referred the gas an ideal gas, would the statements be same??

 

[Minato112]

Thanks, u made me relieved....o and if i referred the gas an ideal gas, would the statements be same??

hmm I guess whether the gas is ideal or real is irrelevant here... Well thats my opinion at the very least...

 

[Hemdon]

Hi, im back with another doubt, keeping u guys bzy lol... , anyways here it is:
A young modulus of a wire is 0.17TPa. the cross-sectional area of a wire is 0.18mm^2. The wire is extended by a force F. This causes the wire to be increased by 0.095%.
Calculate stress and the forece F.

 

[Buzzkiller]

what is sound level room away from the speaker whose output is 120 W?
Help needed,fast!

 

[azhutosh]

I have problem with waves ( As level). Can anyone tell me how to sketch waves with phase difference 60, 90 etc..

 

[KWIKIW]

I need help with a few questions on simple harmonic motion.
(1)What happens to the amplitude of oscillation when resonant frequency,f0 is halved in a mass spring system?
(2)What is the difference between resonant frequency and angular frequency?
(3)Is there a difference between resonant frequency and natural frequency?

 

[Raiyan3]

Can someone please explain 7(c)
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s05_qp_2.pdf

 

[DumbIdiot]

check out physics p12 no 23 and p13 no 19. arent the two questions the same and yet the answers on the ms do not match. or am i missing something?

 

[Shaddy]

Hey.im stuck with waves...so pls help me out.has anybody got detailed notes for waves????and can anyone explain me the difference between path difference and phase difference???and what is coherent waves???(i know that it means waves having constant phase diference but then i dont get...what does it mean by constant phase??????)

 

[harishkum]

someone plzz help me
question no 5
here is the link : http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_43.pdf

im stuck in drawing the graph plzz help me
plzz give me examples

 

[Abdul Malik]

Help me with these questions guys. your help is much appreciated, God bless amin...!

 

[gary221]

someone plzz help me
question no 5
here is the link : http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_43.pdf

im stuck in drawing the graph plzz help me
plzz give me examples

i think this is how u do it.

 

[gary221]

Can someone please explain 7(c)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s05_qp_2.pdf

7 c) As we can see in the graph, power = 1.05 W at 2 values of V, when V = 1.12V, and when V = 1.9V.
V = the voltage across the resistor R.

So, when the voltage across R is higher → voltage across r will be smaller.
(becoz R and r are in series, and in series, voltage is divided between components according to the proportion of their resistances)

So, if voltage across r is smaller, and I is constant → P dissipated in r will be smaller.
(As P = VI)

So, the GREATER value of V → LESSER power being dissipated in r.

Hope you get it.

 

[Isaac CKR]

2012 Paper 1 Variant 1 : http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s12_qp_11.pdf
Answers : http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s12_ms_11.pdf

I need help in understanding :
Q8 - B. I keep getting 0.5T, a=(L/T)
Q10 - C. I understand that a=dV/dt and mass is a constant but why can't it be B, Force = mass x acceleration
Q12 - A. What equations do you use?

 

[johnjase0]

can anyone send me a level full physics revision notes and worksheet plzzzzzzz
i need it plzz some one help me if you have it send it to [email protected] and if you need any other help in AICT and maths i will help you
but plzzz send me notes guys

 

[Suchal Riaz]

Anyone please tell me which books are best for physics and why they are best.

 

[Jaspreet Dhaliwal]

can someone please help me with this question, the answer is B by the way

 

[salvatore]

http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_w05_qp_4.pdf
Could anyone please help me with qn no. 1 (b)? I don't understand what the marking scheme has d0ne..
Thanks

 

[adibshamsuddin]

E =-V/D .Why the minus sign?? book says V increases towards the right and F is in the opposite direction. What they do mean by V increases towards the right???

 

[snowbrood]

E =-V/D .Why the minus sign?? book says V increases towards the right and F is in the opposite direction. What they do mean by V increases towards the right???

The force on the charge is F = qE where E is the field pushing the charge q. So the work done on the charge is just Q = Fd = qEd = q(V/d)d = qV; where E = V/d is the field between the two plates with voltage V and distance d.
note if the object moves in the direction of applied force the work done is positive however if the object movers in opposite direction then work done is negative in this case force is from positive to negative plate while the electron moves from negative to positive