Physics Discussion HERE ONLY!

[hmh]

Erm, man the windmill question was a little depressing 

Anyway, what I did was.. erm

It's hard to recollect 

I guess there was a question before the one where we had to find the mass, where they asked us to find out the power... shwoing all your calculations
Using the efficiency percentage they gave as 10%, I calculated the Energy as 54,000 Joules.
THEN, the E=Pt P= E divided by T. 54000/1 = 54,000 W (watts)

Then, erm, I was really confused for the next one.
I thought about using the Energy formula itself like KE= 0.5 mv²
but then i thought.. if the velocity is halved, how would the mass increase  cuz technically if the velocity decreased, then the mass of air passing through the turbines should fall...
... So I just used a ratio and got an answer I can't seem to remember 

BUT I think I'm wrong. As they said earlier, probably a heavier mass would mean that speed has decreased 
BUT I DID get the fraction as 1/8... These two answers were really difficult   

most people got 1/8... i guess it the correct answer.. hopefully.. or maybe we all are wrong and examiners have something completely different to amaze us wen freeexampapers get the question paper and mark schemes lol

[MR.BooMBastiC]

nice...rep kill..

[care]

Erm, man the windmill question was a little depressing 

Anyway, what I did was.. erm

It's hard to recollect 

I guess there was a question before the one where we had to find the mass, where they asked us to find out the power... shwoing all your calculations
Using the efficiency percentage they gave as 10%, I calculated the Energy as 54,000 Joules.
THEN, the E=Pt P= E divided by T. 54000/1 = 54,000 W (watts)

Then, erm, I was really confused for the next one.
I thought about using the Energy formula itself like KE= 0.5 mv²
but then i thought.. if the velocity is halved, how would the mass increase  cuz technically if the velocity decreased, then the mass of air passing through the turbines should fall...
... So I just used a ratio and got an answer I can't seem to remember 

BUT I think I'm wrong. As they said earlier, probably a heavier mass would mean that speed has decreased 
BUT I DID get the fraction as 1/8... These two answers were really difficult   

why do you think that those wind mills (i can't remember the real name) are built in places with a lot of wind (with a high speed)? because, the faster the wind is, more air passes through the windmill... so, when the speed of wind is halved, than the mass of air is halved... so 1/8 is the correct answer!

[MR.BooMBastiC]

ok ppl its past and i think u should forget it

[care]

i agree

[sweetie]

just one last que.
in da diode que. was it given dat da diodes work in reverse bias???//
plzzzzzz reply dats my last que.

[hmh]

just one last que.
in da diode que. was it given dat da diodes work in reverse bias???//
plzzzzzz reply dats my last que.

I dont think it said it worked reverse or anything like tht.. it jst mentioned tht it shod go from red to black and its normal diode. They were very very trickly placed in diagrams.. I got D as answer.. many ppl put A and C.. no one did B so i guess B is definately wrong.. or possible we are all wrong and B is correct who knows.. lool.

[Bani]

just one last que.
in da diode que. was it given dat da diodes work in reverse bias???//
plzzzzzz reply dats my last que.

I dont think it said it worked reverse or anything like tht.. it jst mentioned tht it shod go from red to black and its normal diode. They were very very trickly placed in diagrams.. I got D as answer.. many ppl put A and C.. no one did B so i guess B is definately wrong.. or possible we are all wrong and B is correct who knows.. lool.

I put B ......I wonder....

[hmh]

just one last que.
in da diode que. was it given dat da diodes work in reverse bias???//
plzzzzzz reply dats my last que.

I dont think it said it worked reverse or anything like tht.. it jst mentioned tht it shod go from red to black and its normal diode. They were very very trickly placed in diagrams.. I got D as answer.. many ppl put A and C.. no one did B so i guess B is definately wrong.. or possible we are all wrong and B is correct who knows.. lool.

I put B ......I wonder....

oh lool.. i take my words back then.. B is definately not wrong... but it culd be wrong .

[Bani]

just one last que.
in da diode que. was it given dat da diodes work in reverse bias???//
plzzzzzz reply dats my last que.

I dont think it said it worked reverse or anything like tht.. it jst mentioned tht it shod go from red to black and its normal diode. They were very very trickly placed in diagrams.. I got D as answer.. many ppl put A and C.. no one did B so i guess B is definately wrong.. or possible we are all wrong and B is correct who knows.. lool.

I put B ......I wonder....

oh lool.. i take my words back then.. B is definately not wrong... but it culd be wrong .

[Muho]

the answer for the Diode is C. 2 diodes facing each other wouldn't make a current flow. C was from black to red, and D was from red to black. A and B would have no current because the whole point of the diode is to make the current flow one way, and if the two are facing each other then where the hell will the current flow? xD they say common sense is not common, i certainly agree. -.-

[Bani]

the answer for the Diode is C. 2 diodes facing each other wouldn't make a current flow. C was from black to red, and D was from red to black. A and B would have no current because the whole point of the diode is to make the current flow one way, and if the two are facing each other then where the hell will the current flow? xD they say common sense is not common, i certainly agree. -.-

Having a bad Physics teacher will lead students like me to give such answers.-.-
so I guess they also say that good teachers are not common, to which I certainly agree,-.-

[17]

hey guys


You know, in all year 9, we had the worst teacher ever he started the year WITH ELECTRICITY!! HAHA IMAGINE AND WE WERE LIKE WTH IS HE TALKING ABOUT!! Looool


So this year a real expereienced IGCSE physics teacher starting teaching us, we started from the begging and it took us only 4months to finish the whoooole thing, thats by feb!!, then we did past papers like 6 years and everybody was just amazing at physics


I found the exam very simple and straight forward, most of it was general physics, no motors no generators etc,


Guy what did u get for the diode?? was it A??

Thanks

[ADIN]

what is the answer to the metal question? i wrote aluminium - which i think is wrong (although i hope they condone it). its probably steel but do u think theyll pardon aluminium?

[karim]

da pressure will be da same, da guy is applying da same pressure but due to da difference in the areaz it pains him more but da guy is applying da same force.