Physics: Post your doubts here!

[RadzMau]

Hi! I need help pls!
My question is:
'Assuming that the Moon travels at a a constant speed around the Earth at the centre of the circle, calculate the acceleration of the Moon.'

 

[Pradeep Adhikari]

Friend, Read this, it may be more than useful to you.....
http://www.physicsclassroom.com/Class/vectors/

 

[Pradeep Adhikari]

Please Help GUYS............................................How can uranium exist in many isotopes?

 

[Minato112]

Hi! I need help pls!
The question is: "Why does the moon not fall and hit the earth?"

The gravitational force of the earth provides the centripetal force for the circular motion of the earth. Thus the moon continues in its state to motion instead of colliding with the earth

 

[Hemdon]

hi guys, question is " use kinetic model to explain the pressure exerted by a gas"...4 marks....and I wrote" A gas exerts pressure on any surface that comes into contact. There are 2 factors that must be taken into consideration, the force of the particle or atom at which it exerts the walls of the container, and the mass of the particle. The kinetic model states that the rate of the fore applied on the wall of the container, and the particle must be equal, resulting in a constant pressure throughout." is this correct, because i feel something is irrelevant and im missing some details, if u can help me out I'll be very grateful. fell free to tell me and correct me thanks

 

[Minato112]

hi guys, question is " use kinetic model to explain the pressure exerted by a gas"...4 marks....and I wrote" A gas exerts pressure on any surface that comes into contact. There are 2 factors that must be taken into consideration, the force of the particle or atom at which it exerts the walls of the container, and the mass of the particle. The kinetic model states that the rate of the fore applied on the wall of the container, and the particle must be equal, resulting in a constant pressure throughout." is this correct, because i feel something is irrelevant and im missing some details, if u can help me out I'll be very grateful. fell free to tell me and correct me thanks

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

 

[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?