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Author Topic: Physics Help HERE ONLY !!  (Read 81564 times)

Offline astarmathsandphysics

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Re: phy pap 1 here
« Reply #810 on: June 09, 2009, 08:03:29 pm »
If it from a battery it is a straight horizontal line
If it is from a rectifier it is like hills next to each other
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Offline goin4dakill

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Re: phy pap 1 here
« Reply #811 on: June 09, 2009, 08:05:07 pm »
Quote from: astarmathsandphysics on June 09, 2009, 08:03:29 pm
If it from a battery it is a straight horizontal line
If it is from a rectifier it is like hills next to each other

Thanks Astar! So no gaps?? Why did my teacher tell me that -.-
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Offline samin6n

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Re: phy pap 1 here
« Reply #812 on: June 09, 2009, 08:08:15 pm »
MJ 2003 ques.2...why is it B and not C??
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Offline samin6n

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Re: phy pap 1 here
« Reply #813 on: June 09, 2009, 08:10:34 pm »
also ques.9...why is it B?
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Offline bball92

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Re: phy pap 1 here
« Reply #814 on: June 09, 2009, 08:15:26 pm »
i think 2 is a markscheme error because like u sed its c, or at least i got it 2 be c as well.

however 9 is b because its the most stable arrangement. the clamp is steady and the jar or w/e it is is closest to the surface so incase the clamp opens the jar wouldnt smash or anything.
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Offline samin6n

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Re: phy pap 1 here
« Reply #815 on: June 09, 2009, 08:19:39 pm »
ok then...Thanks!...and thnk god!!i thought ppl are dead here!!!!
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Offline bball92

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Re: phy pap 1 here
« Reply #816 on: June 09, 2009, 08:21:06 pm »
lol im sure ppl r revising atm, i am doing past papers from 2002 till 2008 rite now :P and just tooka short break to post here =)
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Offline lana

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Re: Physics Help HERE ONLY !!
« Reply #817 on: June 09, 2009, 09:44:13 pm »
hi ... !! ok i have two questions it's from past papers June and November 03 :

1- the mass of a full bottle of cooking oil is 1.3 kg when exactly half the oil is used  the mass of the bottle and the remaining oil is 0.9 kg what is the mass of the bottle ? now i know it's ''B'' but how ??

2- the half life of a radioactive substance is 5 hours a sample is tested and found to contain 0.48 g of the substance how much of the substance was present in the sample 20 hours before the sample was tested ?? i also know its ''D'' but again how ??

thanks and +rep for anyone who answers =]
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Offline hmh

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Re: Physics Help HERE ONLY !!
« Reply #818 on: June 09, 2009, 09:49:15 pm »
Quote from: lana on June 09, 2009, 09:44:13 pm
hi ... !! ok i have two questions it's from past papers June and November 03 :

1- the mass of a full bottle of cooking oil is 1.3 kg when exactly half the oil is used  the mass of the bottle and the remaining oil is 0.9 kg what is the mass of the bottle ? now i know it's ''B'' but how ??

2- the half life of a radioactive substance is 5 hours a sample is tested and found to contain 0.48 g of the substance how much of the substance was present in the sample 20 hours before the sample was tested ?? i also know its ''D'' but again how ??

thanks and +rep for anyone who answers =]

OK so 1 is B i dnt knw the value  1.3- 0.9 = 0.4 * 2 = 0.8 ... we got 1.3 - 0.8 = 0.5 kg as  0.5 kg mass of bottle.

2 .. again didnt look at the paper.. but guessesing tht answer shd be 7.68g... as 4 half lives reversed as of 5 hrs 1 time.. so 0.48*2*2*2*2 = 7.68.
« Last Edit: June 09, 2009, 09:56:29 pm by hmh »
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Offline MR.BooMBastiC

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Re: Physics Help HERE ONLY !!
« Reply #819 on: June 09, 2009, 09:51:42 pm »
da ist ans is .50kg

the second is 7.68
« Last Edit: June 09, 2009, 09:53:32 pm by MR.BooMBastiC »
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Offline lana

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Re: Physics Help HERE ONLY !!
« Reply #820 on: June 09, 2009, 09:53:44 pm »
exactly 1 - is 0.5 and 2- is 7.68 i'm sorry your work is not right but + rep for u anyway thanks
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Offline hmh

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Re: Physics Help HERE ONLY !!
« Reply #821 on: June 09, 2009, 09:54:49 pm »
Quote from: lana on June 09, 2009, 09:53:44 pm
exactly 1 - is 0.5 and 2- is 7.68 i'm sorry your work is not right but + rep for u anyway thanks

i dnt want +reps lol.. i want to help. srry i misunderstood them.. now i jst corrected... u can check bak :)
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Offline MR.BooMBastiC

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Re: Physics Help HERE ONLY !!
« Reply #822 on: June 09, 2009, 09:55:18 pm »
u want me 2 explain!!!!

i wrote da value wring by mistake!

i hav corrected it

best of luck mate!!
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Offline lana

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Re: Physics Help HERE ONLY !!
« Reply #823 on: June 09, 2009, 09:56:52 pm »
ooh thanks both of you ur both so sweet =]
+ rep 4 u  =p
and best of luck for u 2 !!! =]
« Last Edit: June 09, 2009, 09:59:16 pm by lana »
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Offline Bani

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Re: Physics Help HERE ONLY !!
« Reply #824 on: June 09, 2009, 09:57:18 pm »
Quote from: hmh on June 09, 2009, 09:49:15 pm
Quote from: lana on June 09, 2009, 09:44:13 pm
hi ... !! ok i have two questions it's from past papers June and November 03 :

1- the mass of a full bottle of cooking oil is 1.3 kg when exactly half the oil is used  the mass of the bottle and the remaining oil is 0.9 kg what is the mass of the bottle ? now i know it's ''B'' but how ??

2- the half life of a radioactive substance is 5 hours a sample is tested and found to contain 0.48 g of the substance how much of the substance was present in the sample 20 hours before the sample was tested ?? i also know its ''D'' but again how ??

thanks and +rep for anyone who answers =]

For no.1 : first find the mass of the half of oil( 1.3-0.9=0.4), then u know that other half is 0.4 too. So, subtract the whole mass of oil (0.4*2) from the mass of bottle and oil (1.3) to get 0.5kg
For no. 2: Half life(time for value to half) is 5 hours, and there are 4  5s in 20(meaning you'll have to multiply 0.48 by 2  4 times to get the value 20 hours before decay
so, finally, you'll get 7.68g

I hope this helped

OK so 1 is B i dnt knw the value because i didnt look at exam but shud be 0.25kg becuz.. 1.3/2 = 0.65 half left... but we got 0.9 kg as mass so 0.9-0.65 = 0.25 kg mass of bottle.

2 .. again didnt look at the paper.. but guessesing tht answer shd be 1.92g... as 4 half lives reversed as of 5 hrs 1 time.. so 0.48*4 = 1.92.
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