Physics paper 31 , (a death call)

[Jisu]

but Jisu bro, how do we know the expansion of the flask has an effect so much so that the level of the liquid in it falls

ok,
so..
theres definitely a drop since da solid receives heat first, it expands
comprendez??
movin on, da increase wont be too large or too small
but hello we r talkin abt physics here
anythin dat happens counts
hav a lk at da extract from wiki...pay attention to da highlighted part
i'm a 100% sure abt dis cuz i've asked ma teacher to go thru these small areas...
all in all, we cant satisfy ourselves until we get our hands on da markin schemes
hehe
heres da extract:
For example, a flask, that has been constructed with a long narrow stem filled with enough liquid that the stem itself is partially filled, when placed in a heat bath will initially show the column of liquid in the stem to drop followed by the immediate increase of that column until the flask/liquid/heat bath system has thermalized. The initial observation of the column of liquid dropping is not due to an initial contraction of the liquid but rather the expansion of the flask as it contacts the heat bath first. Soon after, the liquid in the flask is heated by the flask itself and begins to expand. Since liquids typically have a greater expansion over solids the liquid in the flask eventually exceeds that of the flask causing the column of liquid in the flask to rise.
hope i helped

 

[IGCSE O/L student]

ok,
so..
theres definitely a drop since da solid receives heat first, it expands
comprendez??
movin on, da increase wont be too large or too small
but hello we r talkin abt physics here
anythin dat happens counts
hav a lk at da extract from wiki...pay attention to da highlighted part
i'm a 100% sure abt dis cuz i've asked ma teacher to go thru these small areas...
all in all, we cant satisfy ourselves until we get our hands on da markin schemes
hehe
heres da extract:
For example, a flask, that has been constructed with a long narrow stem filled with enough liquid that the stem itself is partially filled, when placed in a heat bath will initially show the column of liquid in the stem to drop followed by the immediate increase of that column until the flask/liquid/heat bath system has thermalized. The initial observation of the column of liquid dropping is not due to an initial contraction of the liquid but rather the expansion of the flask as it contacts the heat bath first. Soon after, the liquid in the flask is heated by the flask itself and begins to expand. Since liquids typically have a greater expansion over solids the liquid in the flask eventually exceeds that of the flask causing the column of liquid in the flask to rise.
hope i helped

thnx.
this proves my brain is stupid!
my answer is wrong!

 

[19loko97]

what about the question about charge and thunderstorms

 

[IGCSE O/L student]

what about the question about charge and thunderstorms

what about it?

 

[19loko97]

was the second question 375000 or something like that

 

[IGCSE O/L student]

was the second question 375000 or something like that

u mean the value of I?

 

[Abu mota]

thnx.
this proves my brain is stupid!
my answer is wrong!

no it doesnt, it just proves that his answer is right, but he didnt say why is evaporation wrong

 

[IGCSE O/L student]

no it doesnt, it just proves that his answer is right, but he didnt say why is evaporation wrong

heheheh...LOL!

 

[19loko97]

u mean the value of I?

no how much energy was lost

 

[IGCSE O/L student]

no how much energy was lost

i got that answer for some question, but i don't remember for which!

 

[19loko97]

i got that answer for some question, but i don't remember for which!

i think I was a 0.25, because the charge was 30c and the time interval was 2 min so 30/120 is 0.25, i think :s

 

[IGCSE O/L student]

i think I was a 0.25, because the charge was 30c and the time interval was 2 min so 30/120 is 0.25, i think :s

I don't remember the value!

 

[19loko97]

ok what about the first question of the paper, i got the average instead of getting the most common one, is this right?

 

[IGCSE O/L student]

ok what about the first question of the paper, i got the average instead of getting the most common one, is this right?

that's what I did.

 

[19loko97]

that's what I did.

great!!! thnx

 

[IGCSE O/L student]

great!!! thnx

don't mention it

 

[kim anika]

but Jisu bro, how do we know the expansion of the flask has an effect so much so that the level of the liquid in it falls

to show the level of water decrease they used used a narrow glass tube where a little increase or decrease in water level is clearly visible

 

[bluefa1con]

IT ISNOT WRONG, the glass expanding is impossible because expansion of solids cant be noticed!!!!!!!!! i dont know why u guys say the expansion of the flask, it just doesnt make sense, also why is evaporation wrong, evaporation can happen at any temperature and rapidly too, so think about it it can never be expansion of the flask. maybe both are right but im 100% sure that evaporation is right and nobody can prove otherwise, ty

you are 100% wrong
someone posted an actual experiment on this thread that proves expansion is the answer

you guys are missing the point
water has a high heat capacity
plus glass is an insulator
so the heat supplied is not enough to raise water's temperature at 1st so the glass expands
evaporation wont happen in that think tube
why? because the tube has thin area
thin area = very slow evaporation = no obvious change

 

[bluefa1con]

i think I was a 0.25, because the charge was 30c and the time interval was 2 min so 30/120 is 0.25, i think :s

yes and the next one was 45000000 i think since W= V * C

 

[Omar Hosny]

LDR WAS AT A !!!!!! 1st gap sureeee...in light R dec. V inc. V around transistor increase positive at the battery was towards A