Physics, Chemistry and Biology: Post your doubts here!

[kboss]

PLZ HEEEEELLPP

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_qp_03.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_ms_3.pdf
q 1 d ii) my answer was 0.72 but it was wrong although i used speed=dist/time the correct answer was 0.36 WHYYYY why did u divide by 2??????????

q 5 c) how do we get the answer????? WE SHOULD ADD THE MINUTES (4) AND ADD THE MASSES why did we subtract 16.3 - 2.1 and why did we use 2 minutes not 4 minutes?????? plzzzzz help me

ok...its quite simple.

for 1 d ii)
the speed that u used was 0.6..correct?
now that speed is actually its maximum speed so it won't be travelling at that speed for the whole 1.2 sec.
thus u divide by 2 to get an average speed = 0.3.
then multiplying 0.3 and 1.2 give 0.36.

for 5 c )
the specific latent heat of fusion is found by how much ice was melted by the heater.
so in order to do that u must know hw much ice was melted by the surroundings.
that amount is given as 2.1...which is the amount which was melted by the surroundings, after the heater was off.
hence even while the heater was on 2.1 g of ice would have been melted by the surroundings.
thus u hv to subtract 2.1 from 16.3, to find out how much ice was melted by the heater.
and since u only hv to find the amount of ice melted by the heater the time is 2min.
hope i helped!!!!

 

[za Shadow]

ok...its quite simple.

for 1 d ii)
the speed that u used was 0.6..correct?
now that speed is actually its maximum speed so it won't be travelling at that speed for the whole 1.2 sec.
thus u divide by 2 to get an average speed = 0.3.
then multiplying 0.3 and 1.2 give 0.36.

for 5 c )
the specific latent heat of fusion is found by how much ice was melted by the heater.
so in order to do that u must know hw much ice was melted by the surroundings.
that amount is given as 2.1...which is the amount which was melted by the surroundings, after the heater was off.
hence even while the heater was on 2.1 g of ice would have been melted by the surroundings.
thus u hv to subtract 2.1 from 16.3, to find out how much ice was melted by the heater.
and since u only hv to find the amount of ice melted by the heater the time is 2min.
hope i helped!!!!

milllllllliioon thankss u r great.....thanks again

 

[thats_me]

ok...its quite simple.

for 1 d ii)
the speed that u used was 0.6..correct?
now that speed is actually its maximum speed so it won't be travelling at that speed for the whole 1.2 sec.
thus u divide by 2 to get an average speed = 0.3.
then multiplying 0.3 and 1.2 give 0.36.

for 5 c )
the specific latent heat of fusion is found by how much ice was melted by the heater.
so in order to do that u must know hw much ice was melted by the surroundings.
that amount is given as 2.1...which is the amount which was melted by the surroundings, after the heater was off.
hence even while the heater was on 2.1 g of ice would have been melted by the surroundings.
thus u hv to subtract 2.1 from 16.3, to find out how much ice was melted by the heater.
and since u only hv to find the amount of ice melted by the heater the time is 2min.
hope i helped!!!!

for the first one can't we use the formula s=ut+1/2at2??

 

[za Shadow]

for the first one can't we use the formula s=ut+1/2at2??

what is this formula?????? do we have to know it????????

 

[kboss]

what is this formula?????? do we have to know it????????

no...
its not in da syllabus

 

[thats_me]

OMG thank you soooo much !! Now i got the whole thing and understood it !! Thx soo much.. any link for how the AC Generator work ?? Thx again so much

http://www.hk-phy.org/energy/power/elect_phy/flash/ac_generator_e.html

 

[thats_me]

what is this formula?????? do we have to know it????????

i don really knw but its in my notes so learned it

 

[thats_me]

no...
its not in da syllabus

so we cant use it? :\ but i got 0.36 using it

 

[kboss]

so we cant use it? :\ but i got 0.36 using it

you can.
its just more complicated

 

[thats_me]

you can.
its just more complicated

oh kk

 

[ZainH]

Small question, how can we tell when to use n = sin i/sin r and when to use n= sin r/sin i ? :S

 

[kboss]

Small question, how can we tell when to use n = sin i/sin r and when to use n= sin r/sin i ? :S

as far as i know its always sin i / sin r

 

[MERIHAN]

Small question, how can we tell when to use n = sin i/sin r and when to use n= sin r/sin i ? :S

ALWAYS KEEP THE ANGLE IN RARER MEDIUM IN NUMERATOR AND THE DENSER MEDIUM IN DENOMINATOR .....IF THE LIGHT IS TRAVELLING FROM GLASS TO AIR THIS MEANS ANGLE OF INCIDENCE IS IN GLASS AND ANGLE OF REFRACTION IS IN AIR SO FOLLOWING THE RULE IT WILL BE SIN R /SIN I

THAT IS WHAT OUR TEACHER TOLD US

 

[za Shadow]

guys help another question
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s08_qp_3.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s08_ms_31+32.pdf
first variant
q 9 c ii) i used the right hand grip rule and the 2 currents were cutting each other in opposite direction so i wrote the the wire moves to the left but the correct answer is exactly opposite WHY????? plzzz help

 

[za Shadow]

ALWAYS KEEP THE ANGLE IN RARER MEDIUM IN NUMERATOR AND THE DENSER MEDIUM IN DENOMINATOR .....IF THE LIGHT IS TRAVELLING FROM GLASS TO AIR THIS MEANS ANGLE OF INCIDENCE IS IN GLASS AND ANGLE OF REFRACTION IS IN AIR SO FOLLOWING THE RULE IT WILL BE SIN R /SIN I

THAT IS WHAT OUR TEACHER TOLD US

thanks that helped me 2

 

[thats_me]

n

Small question, how can we tell when to use n = sin i/sin r and when to use n= sin r/sin i ? :S

it depends ,,if the refractive index of medium is given then its sin in air / sin in medium
and if ref index of air is given then sin in medium / sin in air ....its better if u learn in this way instead of i and r

 

[kboss]

guys help another question
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s08_qp_3.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s08_ms_31 32.pdf
first variant
q 9 c ii) i used the right hand grip rule and the 2 currents were cutting each other in opposite direction so i wrote the the wire moves to the left but the correct answer is exactly opposite WHY????? plzzz help

use the left hand rule...thats it

 

[thats_me]

guyz mj 11 31 2c ..? :S http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s11_qp_31.pdf

 

[za Shadow]

use the left hand rule...thats it

but there is no magnetic field

 

[ThatReallyReallyWeirdDude]

I have my own questions for once.
a) How do you calibrate a CRO?
b) How was the change in velocity found in question 2)c)ii) of the attached past papers?