physics november 2012

[arshadphysics]

which answer have you got for section B number 11 part a ??

 

[ni2005]

which answer have you got for section B number 11 part a ??

i got 2.5 A
there was another question about charge, what is the number of particles?

 

[arshadphysics]

i got 2.5 A
there was another question about charge, what is the number of particles?

the last question in the paper ?

 

[ni2005]

no of particles related to thermionic emission question ?? it was question 6
as One electron has charge of 1.6*10^-19 columb ,
6.25*10^18 electrons would have made one coloumb ..
1 Ampere is 1 Coloumb of charge in 1 second

since current was 0.0058 A ,
so electrons were
0.0058 * 6.25*10^18

and part A was 2.5 Ampere

yeeaahh!!! but i got it wrong!anyways, what about the energy changes, the bungee jumping one?

 

[Nerdz]

How did you do the last question of section b? About the relay thing?

 

[Nerdz]

yeeaahh!!! but i got it wrong!anyways, what about the energy changes, the bungee jumping one?

The energy changes are kinetic energy increases, potential enery decreases, elastic potential energy increases as the spring is stretched and some enery is lost as heat energy

 

[jatin]

in that question of bungee what was the speed we should get

 

[aneeq247]

i wrote potential to kinetic, and then to elastic potential and kinetic again

 

[aneeq247]

did anyone attempt the pressure question? if so, what did u write for the question that asked why a greater pressure was exerted under water

 

[Nerdz]

u could make both Reed Switch or Magnetic Relay .... i drew both , and explained both ...
and how did u do that question in which Filament """ named X " had to be Reflected ...
and that question said .....Draw RAYS ...not a Ray ,,and form image of X ...and label it I this question was of 3 mark ..
one no. was of , labelling " I " , one was , drawing ray from X to Mirror , and ...where the other ray had to be drawn ..i made a straight ray , opposite to mirror ..

I didn't Learn that topic so I just wrote rubbish there! :'(
I didn't do that question! Sorry!

 

[Nerdz]

did anyone attempt the pressure question? if so, what did u write for the question that asked why a greater pressure was exerted under water

There was a greater pressure under water as the volume was less underwater. In the previous part of the question we found out the volume for the balloon while it was underwater and at the surface. In the calculation you would get a greater volume for when the balloon is on the surface. as there is more volume there would be less particles per unit area so less pressure

 

[Nerdz]

what did u write in ...that pressure question in section A .....what was the rise in temprature ???
and the question related to heat capacity ???

I don't remember the pressure question in Section A. The temperature rise is 2.7 degree Celsius and I don't think there was a question to find the heat capacity. Did you do the 21 or 22 paper?

 

[Nerdz]

and how did u find 2.7 degree C

You have to use the equation E= mc(temperature difference) and substitute the values. You would have found the 2300N in the previous part of the question for the force applied or something, so you have to change that force to mass and use it in the equation

 

[Nerdz]

i suppose u are mistaken here ....E represents ENERGY ..not Force ....temprature rise was ...not 2.7
While i got the answer using same formula ....i used the Work done ..which was found earlier as Energy and then used in to find rise in Temprature

That might be correct too! I think we should stop discussing this question now and just hope for the best

 

[aneeq247]

I think the formula was C=Q/Temperature Rise. Correct me if Im wrong. And for the pressure question, I wrote that the air molecules in the ballon had to strike the walls at a greater pressure to keep the balloon inflated, and vice versa on the surface, will that get me some marks?

 

[aneeq247]

Could someone please remind me of the relay question, I attempted the last question but did not see anything related to reed switches or relays.

 

[aneeq247]

Oh and one more question, how did you draw the graph for the question where you had to end the graph at 15 m, it was a curve at first and then a straight line, right?

 

[ni2005]

it was a question related to heat capacity it said that .....
heat capacity is 0.027 g / k , ...find the rise in temprature .....
i am talking of the question of Piston one ???? remember ?

i got 630.something degree celsius

 

[Nerdz]

Oh and one more question, how did you draw the graph for the question where you had to end the graph at 15 m, it was a curve at first and then a straight line, right?

yes!

 

[aneeq247]

Thank God