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Qualification => Subject Doubts => IGCSE/ GCSE => Sciences => Topic started by: Got Tech? GO TECH on May 25, 2010, 12:25:18 pm

Title: Physics paper 1 doubt
Post by: Got Tech? GO TECH on May 25, 2010, 12:25:18 pm
I'm doing summer 2000, and I came across question 13. Can you please explain the solution? Thanks!
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 12:26:18 pm
Please take a screen shot of the question.

I dont have the paper :)
Title: Re: Physics paper 1 doubt
Post by: Got Tech? GO TECH on May 25, 2010, 12:29:35 pm
Here's the link:
http://www.freeexampapers.us/IGCSE/Physics/CIE/2000%20Jun/0625_s00_qp_01.pdf

page 6, q13..Thx!
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 12:34:52 pm
hang on
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 12:37:15 pm
It would be D.

The dam wall needs to be thicker at the bottom. WHY U ask ?

Because pressure INCREASES with depth thus the pressure UNDERWATER is larger than at the surface.

So thicker wall at the bottom to resist the pressure.

GOT IT ?   ;)
Title: Re: Physics paper 1 doubt
Post by: Got Tech? GO TECH on May 25, 2010, 12:38:43 pm
It would be D.

The dam wall needs to be thicker at the bottom. WHY U ask ?

Because pressure INCREASES with depth thus the pressure UNDERWATER is larger than at the surface.

So thicker wall at the bottom to resist the pressure.

GOT IT ?   ;)

Ahh, I see, Thanks a lot!!!
+1 for the quick answer :D
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 12:40:46 pm
No problem ;)
Title: Re: Physics paper 1 doubt
Post by: Weaam on May 25, 2010, 02:45:41 pm
Ive a question, its question37 and 19 in oct/nov 08, and i cant understand them.
Could anyone help me? :-\
Title: Re: Physics paper 1 doubt
Post by: dsiddiqi11 on May 25, 2010, 03:07:04 pm
Ive a question, its question37 and 19 in oct/nov 08, and i cant understand them.
Could anyone help me? :-\

 
37.this is a property of a thermistor:AS TEMP ACROSS THERMISTOR INCREASES THE RESISTANCE DECREASES. so in the question, it says, temp across thermistor increases, so resistance decreases, and when resistance decreases, more current can flow towards the lamp (current and resistance are inversely proportional) , and therefore it gets brighter. ANSWER IS C.

19.hot air always rises and cold air moves down, so the gap is down, so from the heater the hot air goes up and cold air goes down.

   GET IT!!!! ;)
Title: Re: Physics paper 1 doubt
Post by: Snake on May 25, 2010, 03:14:03 pm
Ive a question, its question37 and 19 in oct/nov 08, and i cant understand them.
Could anyone help me? :-\

Q37=C: This is because the Thermistor gets heated, so Voltage decreases and remember R=V/I, if V decreases then R decreases allowing a stronger current hence brighter lamp!
Q19=B: This is to do with Convection Currents, remember Hot rises, Cold sinks. When the heater heats the hot air rises above the cupboard while the cold air would normally have to go under the cupboard and towards the heater. See the attached picture!

Hope I helped :)
Title: Re: Physics paper 1 doubt
Post by: Weaam on May 25, 2010, 03:40:30 pm
Thanks you guys, i get it now, and thanks snake for the picture, that really helped me understand, ill +1 u guys.
Thanks again  ;)
Also from the same year could you please explain Q12 please, sorry for the trouble  :-\
Title: Re: Physics paper 1 doubt
Post by: J.Darren on May 25, 2010, 03:50:15 pm
Thanks you guys, i get it now, and thanks snake for the picture, that really helped me understand, ill +1 u guys.
Thanks again  ;)
Also from the same year could you please explain Q12 please, sorry for the trouble  :-\
Atmospheric pressure in the case of a barometer is when the reading of the mercury height on the tube reads 760 mm. Inside the tube the atmospheric pressure at the reservoir supports the arrangement, thus sustaining P at the 760 mm point. It essentially pushes up the mercury to that height. Hence the pressure at the reservoir would be the heaviest, whereas the pressure at the top would be the lowest.
Title: Re: Physics paper 1 doubt
Post by: Weaam on May 25, 2010, 03:59:26 pm
Atmospheric pressure in the case of a barometer is when the reading of the mercury height on the tube reads 760 mm. Inside the tube the atmospheric pressure at the reservoir supports the arrangement, thus sustaining P at the 760 mm point. It essentially pushes up the mercury to that height. Hence the pressure at the reservoir would be the heaviest, whereas the pressure at the top would be the lowest.
Im sorry, I dont get it, simpler explanation please, like REALLY simple. thanks
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 04:06:14 pm
Im sorry, I dont get it, simpler explanation please, like REALLY simple. thanks

Which year ?
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 04:10:48 pm
Check the picture.
Title: Re: Physics paper 1 doubt
Post by: Weaam on May 25, 2010, 04:13:07 pm
Thanks dude! i get it now! thanks.  ;D
Title: Re: Physics paper 1 doubt
Post by: Weaam on May 25, 2010, 04:21:22 pm
Ummm, anuther question, Q37 May/June 08 page 17, i thought the answer is B but ms says C. I dunt get it.
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 04:24:04 pm
Ummm, anuther question, Q37 May/June 08 page 17, i thought the answer is B but ms says C. I dunt get it.

Wait.
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 04:26:48 pm
say the voltage is 6V

first diagram the 100 ohms (connected to Voltmeter) gets 100/200 * 6 = 3

for the second diagram the 100 ohms gets 100/190 * 6 = 3.15

thus increases a little
Title: Re: Physics paper 1 doubt
Post by: Weaam on May 25, 2010, 04:39:38 pm
say the voltage is 6V

first diagram the 100 ohms (connected to Voltmeter) gets 100/200 * 6 = 3

for the second diagram the 100 ohms gets 100/190 * 6 = 3.15

thus increases a little

Thanks SO MUCH! I owe you one!  ;)
Title: Re: Physics paper 1 doubt
Post by: Snake on May 25, 2010, 04:45:03 pm
Sorry for not replying was in another thread helping out :)
Title: Re: Physics paper 1 doubt
Post by: holtadit on May 25, 2010, 04:58:52 pm
@weaam

We can help you out FASTER and BETTER if you post your doubts here :

https://studentforums.biz/index.php/topic,6468.msg224536/boardseen.html#new
Title: Re: Physics paper 1 doubt
Post by: Weaam on May 25, 2010, 05:09:39 pm
@weaam

We can help you out FASTER and BETTER if you post your doubts here :

https://studentforums.biz/index.php/topic,6468.msg224536/boardseen.html#new
Will do! ;) thanks