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jellybeans:

--- Quote from: Navthep on May 25, 2010, 01:13:58 pm ---Um, can anyone explain convection currents? I'm somewhat confused :S
Thankss :D

pS - Thanks to all who explained me thermal capacity. Really mean it. :)


--- End quote ---

hot air rises and cold air falls. this is cuz when something is hot, it has more energy to move around hence it moves further apart and become less dense.. so it rises ... and cold air is closer together hence denser.. so it falls... :)

Moonlyte:
I have problems with the following questions of june 2009:

#30:C
#31:A
#34:C
#37:A

Those are the answers but I dont know why. Please help!

Link for the paper:

http://www.freeexampapers.com/FreeExamPapers.com_.php?__lo=SUdDU0UvUGh5c2ljcy9DSUUvMjAwOSBKdW4vMDYyNV9zMDlfcXBfMS5wZGY=

Snake:
Ok gimme 5 mins I'll explain

8T:
For # 30 take say 5 for each resistor and remember that in C it is connected in parallel and that u use the equation R=R1*r2 over(divided by)R1+R2
I will check the rest and come back to yew dear :)

holtadit:

--- Quote from: 8T on May 25, 2010, 01:29:03 pm ---Anyone cares to explain to me q 14 o/n 04 p1 ofc .. why is it B i thought it would be A more force per unit are ??


--- End quote ---

Only a temperature INCREASE would give the molecules more KINETIC ENRGY and cause GREATER/HARDER  collisions.

BUT the question says the TEMPERATURE WAS CONSTANT.

But the VOLUME DECREASED. So there are more air molecules per unit area and hence more FREQUENT collisions with the walls of the pistons.

This causes a pressure INCREAsE.

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