Physics Help HERE ONLY !!

[hmh]

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.

yea lol.. i corrected myself thanks anyway

[MR.BooMBastiC]

anything else lana

i will be more than happy to help u...

[lana]

thank uuu sooo much =]

[Petrol]

heyy november 2003 question 3 it doesnt make sense are u sure the mark scheme is correct i think it should be D but it says A :s

[MR.BooMBastiC]

no problem

it was nice talking to u!!

[lana]

ya it's A because the car starts to accelerates so it's slowest at the start then the speed increases until it reaches pole 4 and stays at the same speed !! hope u got it

and MR.BooMBastiC ! it was great talking to u 2 =]

[hmh]

heyy november 2003 question 3 it doesnt make sense are u sure the mark scheme is correct i think it should be D but it says A :s

It should be A.. as it asks for the most/ greatest time to pass throught poles.. so tht is 1 and 2 wen the car is slowly accelerating to high speed.

[astarmathsandphysics]

heyy november 2003 question 3 it doesnt make sense are u sure the mark scheme is correct i think it should be D but it says A :s

it is a

it takes longest when it is travelling slowest ie between the first 2 poles

[MR.BooMBastiC]

U R  right!!  astarmathsandphysics

[nid404]

U are so unkind u swine...

People need to get into university, and i am helping people with it!!!

if ur so confident of ur answers, keep them to urslf, or contribute like me!

By the way crudity is not tolerated..

u have been reported..the moderator will decide ur fate

[esso]

thats wat he deserves......kicked out of this forum....

i saw this answers bt they r wrong...most of dm,,,,,

u know i just came from the exam....its easy .... does not require cheating at all....

nd with this cheated answers u ll get less marks then u coud have got....

[nid404]

thats wat he deserves......kicked out of this forum....

i saw this answers bt they r wrong...most of dm,,,,,

u know i just came from the exam....its easy .... does not require cheating at all....

nd with this cheated answers u ll get less marks then u coud have got....

Thanks for the support

[Friends]

His most the answers are wrong. Definitely last 2 are wrong.



And plzzz moderater dont ban me for this:

ANSWERS GO F**K URSELF.

[esso]

+rep for u all for keeping the forum clean.....

[nid404]

+rep for u all for keeping the forum clean.....

for u too...but the forum is not clean cuz the site is still in many threads and circulating. I hope the moderator reviews this and takes action