Physics: Post your doubts here!

[Rockstar RK]

Ek aur doubt hai: From the formula in electrostats F=(1/4pi E0 K)(q1q2/r^2) me metal ka dielectric constant(K) infinite hota hai to fir electron circuit me kyu move kar te hai???????????????????

Jab ke us ke upar force zero hota hai

 

[Zepudee]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_42.pdf

Hey guys, can help me with 2(b) (iii) R to P that column, work done on gas? Why?

 

[Thought blocker]

internal energy = (heat supplied) + workdone
for P-Q u find wd in part1
so just add
for Q-R workdone = 0 so U= 720
for R-P
u know sum of all IE are 0
now calc third IE
put in formula IE = q + WD
and get the wd

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_42.pdf

Hey guys, can help me with 2(b) (iii) R to P that column, work done on gas? Why?

 

[Ionisation]

AsalamoAlikum
Im new in AS level , so which books shall I read in order to get A* in Physics

 

[Thought blocker]

AsalamoAlikum
Im new in AS level , so which books shall I read in order to get A* in Physics

Use David Sang course book. Wait for someone else reply.

 

[Wolfgangs]

Guys for the practicals in Q1, there is a table drawing and taking the readings and adding it to it. Well, what if the table is correct, units and significant figures, but only the trend of readings is wrong. How much will I lose from that table question. Will they then subtract marks from my graph and gradient, even though they are correct with my results>?

 

[Thought blocker]

Rockstar RK
I am sorry, I dont know.

 

[Thought blocker]

Guys for the practicals in Q1, there is a table drawing and taking the readings and adding it to it. Well, what if the table is correct, units and significant figures, but only the trend of readings is wrong. How much will I lose from that table question. Will they then subtract marks from my graph and gradient, even though they are correct with my results>?

Which variant ?

 

[Wolfgangs]

Which variant ?

Variant 1

 

[Thought blocker]

Variant 1

Oh I gave variant 4

 

[Muskan Achhpilia]

I have doubt please can someone help,

A non-uniform plank of wood XY is 2.50m long and weighs 950N. Force-meters (spring balances) A and B are attached to the plank at a distance of 0.40m from each end, as illustrated in the Figure below

When the plank is horizontal, force-meter A records 570N

(i) Calculate the reading on force-meter B
(ii) Determine the distance of the center of gravity from the end X of the plank.
Summer 2002 Paper 2 Q3 (9702)

I got first part as it is 380N however in the second part I am getting-
Clockwise moment=Anticlockwise moment
Let distance be x
570*1.7=950x+380*1.7
So the distance is coming as 0.34m

However in the marking scheme the answer given is 1.08m,Can someone please explain how?

Thanks a lot

 

[Thought blocker]

I have doubt please can someone help,

A non-uniform plank of wood XY is 2.50m long and weighs 950N. Force-meters (spring balances) A and B are attached to the plank at a distance of 0.40m from each end, as illustrated in the Figure below

When the plank is horizontal, force-meter A records 570N

(i) Calculate the reading on force-meter B
(ii) Determine the distance of the center of gravity from the end X of the plank.
Summer 2002 Paper 2 Q3 (9702)

I got first part as it is 380N however in the second part I am getting-
Clockwise moment=Anticlockwise moment
Let distance be x
570*1.7=950x+380*1.7
So the distance is coming as 0.34m

However in the marking scheme the answer given is 1.08m,Can someone please explain how?

Thanks a lot

Here :¬

 

[Thought blocker]

Jab ke us ke upar force zero hota hai

Well this was easy one wo isiliye to move karta hain.. LOL

 

[Thought blocker]

Jab ke us ke upar force zero hota hai

Will solve your other doubt as soon as I get it. Wait.

 

[Zepudee]

Explain why external work is done by boiling water
MS: volume increases on evaporation ( what does this mean? )
so work done pushing back against atmosphere. Can someone clear my doubt please?

 

[Thought blocker]

Explain why external work is done by boiling water
MS: volume increases on evaporation ( what does this mean? )
so work done pushing back against atmosphere. Can someone clear my doubt please?

Thermodynamics deals with closed systems, you are talking about an open system where the steam escapes (and you say does some work).

The steam is composed of molecules with the most energy, therefore you are always losing the higher energy ones, and are left with the average heat energy going down.

Hence, Volume of gas in much greater than volume of liquid.

 

[Zepudee]

Thought blocker When do i know is work done by system or work done on system? You leaving? You wont be on community anymore?

 

[Zepudee]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_42.pdf

How to do 2(b) (iii) ? helpppp, just to help with the third column, i cant get the answer. Well, i got 840 but i got it as +, why is it -?

 

[Thought blocker]

Thought blocker When do i know is work done by system or work done on system? You leaving? You wont be on community anymore?

Yes I wont be.

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_42.pdf

How to do 2(b) (iii) ? helpppp, just to help with the third column, i cant get the answer. Well, i got 840 but i got it as +, why is it -?

Look I explained you previously as well.
The third IE = -360, If you don't know how ? Then have a look again to my previous post. If still its not clear here you go :¬
WE KNOW THAT SUM OF ALL IE IS ZERO.
SO -360 + 720 + x = 0 ; x = - 360. Hence Our third IE is -360.
Now simply use the formula as we used to get the other two answers, that is "internal energy = (heat supplied) + workdone" So to find workdone, "WD = IE - q"
Using it, we get WD = -360 - 480 = -840J.

Hope you got it.

 

[Zepudee]

Yes I wont be.

Look I explained you previously as well.
The third IE = -360, If you don't know how ? Then have a look again to my previous post. If still its not clear here you go :¬
WE KNOW THAT SUM OF ALL IE IS ZERO.
SO -360 + 720 + x = 0 ; x = - 360. Hence Our third IE is -360.
Now simply use the formula as we used to get the other two answers, that is "internal energy = (heat supplied) + workdone" So to find workdone, "WD = IE - q"
Using it, we get WD = -360 - 480 = -840J.

Hope you got it.

Thank you so much, I get it now Take care