Physics: Post your doubts here!

[Ding Ding]

A capacitor of capacitance C1 is charged to a p.d. of V0. The charging battery is then removed. A second capacitor of capacitance C2 is now joined to C1. (C2 is initially uncharged.)
(a) What is the final p.d. across the combination?
(b) If C2 is now disconnected, discharged and then connected to C1 again, and the process is repeated as before, what id the charge remaining after the tenth disconnection?
Please help me! I 'm really dunno how to answer this question . T_T

 

[Thampi4]

this question is physics A2 p4 O/N 08

hello
can someone pls explain me question
1aiii),b)
7ci),ii)


thanks in advance.

 

[saadatrezvi]

Physics 9702/M/J/09....MAY JUNE 09 paper 1 question# 15....can please anyone tell me that why the answer to this MCQ is option B? The new height after water flows from X to Y would be h/2
.

 

[Muhamad Y]

does potential increase because of resistance as more work has to be done on the charge

 

[Syafiq]

any1 have the marking scheme for summer 2001? Thanks

 

[Prakhar]

Physics 9702/M/J/09....MAY JUNE 09 paper 1 question# 15....can please anyone tell me that why the answer to this MCQ is option B? The new height after water flows from X to Y would be h/2
.

that is because formula is MxGxH
the mass decreased is M/2 , height decreased is H/2 ,The G(gravity) remains the same...
so when you multiply them the answer will be MGH/4
hence the option B is correct

 

[Prakhar]

A car travels one complete lap around a circular track at a constant speed of 120 km/hr. Determine the magnitude of the displacement of the car in a time of 1.0 minute. (The circumference of a circle is 2πR where R is the radius of the circle.)

the displacement is zero because....
displacement=distance moved from one point to another OR you can also say it as the shortest distance between two points..
so when the car will move in a circular track the R(radius) remains the same..that means the distance between the center of the circular track and car is always same..
hence the displacement is zero

if you are asking for the distance covered...it is 2km in one minute

 

[scouserlfc]

does potential increase because of resistance as more work has to be done on the charge

It depends on what type of circuit you are using and what is happeneing to the current whether it is increasing or not ???

 

[scouserlfc]

This is an Edexcel question that I'm having trouble with. I'll write my answer and can someone please point out what's wrong with it (4 marks):
Newton's first law states than an object would continue with constant velocity or remain stationary if there;s no resultant force. When the train decelerates, there is a resultant force acting on each person in the direction that the train is travelling in. THis means that person A would fall and collide with person B as persons B and C would remain in their seats due to the fact that they have their backs on chairs which would absorb the force. Person A's motion is an example of a resultant force quoted in Newton's first law.

I'm pretty sure there's something wrong in there because not each point matches the mark scheme but that is how I would answer it, so does anyone know how they would go about correcting this?

It depends on how many of your points match if 4 are matching then its okay but if not then probably talk in detail and talk abt the inertia ! If u still have problem give the link of the question or state the points of ms because i cudnt find any other point !

 

[snowbrood]

This is an Edexcel question that I'm having trouble with. I'll write my answer and can someone please point out what's wrong with it (4 marks):
Newton's first law states than an object would continue with constant velocity or remain stationary if there;s no resultant force. When the train decelerates, there is a resultant force acting on each person in the direction that the train is travelling in. THis means that person A would fall and collide with person B as persons B and C would remain in their seats due to the fact that they have their backs on chairs which would absorb the force. Person A's motion is an example of a resultant force quoted in Newton's first law.

I'm pretty sure there's something wrong in there because not each point matches the mark scheme but that is how I would answer it, so does anyone know how they would go about correcting this?

here's my answer:
in order to counter balance the sudden deceleration of train A resultant force would act in direction opposite of the direction of deceleration. passengers at b and C therefore would stay at their seats. and due to change in velocity and no seat to hold on to the passenger A moves forward eventually clashing with B.

 

[yuliana95]

Hi Guys... I have problems solving this question, Please help me...

A pile driver supported by a crane is used to drive a vertical steel girder of mass 900kg into the ground. The pile driver has an 80g steel 'hammer' which is raised 4.0m above the top end of the girder then released to strike the end of the girder and drive it further into the ground. Each impact drives the end of the girder 0.4m further into the ground. Assuming the pile driver does not bounce, calculate:

1. the speed of the pile driver just before impact? ans: 8.94m/s
2. the speed just after impact? ans: 0.730m/s
3. the force of friction on the girder as it penetrates the ground? ans:653N

Thank youuu soo much for helping..

 

[Oliveme]

Can someone please help me with this question?

I just can't seem to get the right answer

A particle moves with SHM (simple harmonic motion) of period 4 seconds and amplitude 4 metres. its displacement from the equilibrium position is x. find the time taken for it to travel -

a) from x= 4m to x= 3m
b) from x= -4m to x= 3m


Thank you very very much.

JazakAllahu Khairan

 

[nightrider1993]

Can someone please help me with this question?

I just can't seem to get the right answer

A particle moves with SHM (simple harmonic motion) of period 4 seconds and amplitude 4 metres. its displacement from the equilibrium position is x. find the time taken for it to travel -

a) from x= 4m to x= 3m
b) from x= -4m to x= 3m


Thank you very very much.

JazakAllahu Khairan

a)
Angular velocity=w= 1.5708 rad/s

Time it takes for quarter oscillation(ie from 0m to 4m)= 4/4 = 1s
or the technical way

x= xo sin(wt)​

4=4 sin(1.5708 * t)​

t = 1s​

Time it takes to reach 3m from zero(starting position):

x= xo sin(wt)​

sin(1.5708*t) = 3/4​

t= 0.5399​

therefore, time from 4m to 3m= 1-0.5399 = 0.46s

b) Time it takes from -4m to 3m = 1+ 0.5399 = 1.54s

Let me knw if u want a picture to help u visualize.

 

[nightrider1993]

This is an Edexcel question that I'm having trouble with. I'll write my answer and can someone please point out what's wrong with it (4 marks):
Newton's first law states than an object would continue with constant velocity or remain stationary if there;s no resultant force. When the train decelerates, there is a resultant force acting on each person in the direction that the train is travelling in. THis means that person A would fall and collide with person B as persons B and C would remain in their seats due to the fact that they have their backs on chairs which would absorb the force. Person A's motion is an example of a resultant force quoted in Newton's first law.

I'm pretty sure there's something wrong in there because not each point matches the mark scheme but that is how I would answer it, so does anyone know how they would go about correcting this?

Newtons first law states that a object would continue in its state of motion unless a external force is applied. As the train decelerate, all the three people would continue to move at the original acceleration of the train. Person B and C would be stopped by the seats as the seats absorb the momentum of the people. Whereas, person A would move forward due to inertia causing him to collide with the person B. Therefore, person C's seat would be the safest.

I dont know if my one is gud enuf.

 

[Adil Bhatti]

please can anyone help me with a link for topic wise pastpapers for p2 and p4??? thnks in advance

 

[daredevil]

please can anyone help me with a link for topic wise pastpapers for p2 and p4??? thnks in advance

http://www.xtremepapers.com/community/threads/physics-p1-p2-p4-past-papers-chapter-wise-d.13931/


u're welcum

 

[daredevil]

Heyya guys
FRom amongst the three graphs of electricity... the last one 'velocity against distance travelled by a charged particle initially at rest in a uniform electric field' :

why do we use the formula:-
2as = v^2 - u^2
??
and then make the graph?? i don't get it! :/

 

[Oliveme]

a)
Angular velocity=w= 1.5708 rad/s

Time it takes for quarter oscillation(ie from 0m to 4m)= 4/4 = 1s
or the technical way

x= xo sin(wt)​

4=4 sin(1.5708 * t)​

t = 1s​

Time it takes to reach 3m from zero(starting position):

x= xo sin(wt)​

sin(1.5708*t) = 3/4​

t= 0.5399​

therefore, time from 4m to 3m= 1-0.5399 = 0.46s

b) Time it takes from -4m to 3m = 1+ 0.5399 = 1.54s

Let me knw if u want a picture to help u visualize.

Thank you so much!
It helped a lot.

 

[Tabi Sheikh]

please can anyone help me with a link for topic wise pastpapers for p2 and p4??? thnks in advance

http://www.xtremepapers.com/community/threads/some-different-notes-website-are-available.10423/
follow the link there are different links including topic wise pastpapers

 

[soul]

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.

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

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)

thnanks a lot for these notes man
but the mediafire link for paper 2 and paper 4 is not working
whenever i click on it i get a message that the link is valid or the files have been deleted