IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: [Spy] on May 20, 2010, 10:49:59 am

Title: Mechanics Paper 42 Solutions
Post by: [Spy] on May 20, 2010, 10:49:59 am
guys here are the solutions for the whole paper :) and im very sure of them :)

1) a=0.845

2) i) 0.09
    ii) 1.08
    iii) 0.72

3) i) 3.05
    ii) 1.62

4) 500N 38.9 to the x-direction

5) i) 3
    ii) 0.32

6) i) a=6 & v=3.95
    ii) i did a silly mistake here so i dont know the right answer. someone post it

7) i) A=4 & B=3375
    ii) -3375/t + k (though i did a silly mistake here i forgot to put K, GODDD!!! :@) so i dont know the value of K
    ii) DO YOU GUYS THINK I'D GET AN ECF? :( answer was something around 5.4

:)
Title: Re: Mechanics Paper 42 Solutions
Post by: XaM!! on May 20, 2010, 11:05:42 am
ur ans r same as mine... BUH I ****ed one part.. my acc came 6 but V wasnt coming 3.95. wat do u thnk how many marks will deduct??? it was of 7 marks... i got acc 6..

n my B was coming in negative... -377smthn...
Title: Re: Mechanics Paper 42 Solutions
Post by: neno on May 20, 2010, 11:07:37 am
how many marks was 5 ii) worth....how r u sure these r the ryt answers....i got all the same answers other than this part sumhow i got 0.13 as the height
dont u do 1.35-workdone against resistance=ke-pe
then PE =0.39 i think i dont remember
 
Title: Re: Mechanics Paper 42 Solutions
Post by: panther on May 20, 2010, 11:11:23 am
For question 4 it was 36.9 to the x-direction
Title: Re: Mechanics Paper 42 Solutions
Post by: neno on May 20, 2010, 11:13:23 am
For question 4 it was 36.9 to the x-direction

yea i think i got tht 2 cant remember the figures tht well
Title: Re: Mechanics Paper 42 Solutions
Post by: XaM!! on May 20, 2010, 11:15:17 am
how many marks was 5 ii) worth....how r u sure these r the ryt answers....i got all the same answers other than this part sumhow i got 0.13 as the height
dont u do 1.35-workdone against resistance=ke-pe
then PE =0.39 i think i dont remember
 

ya

P.E = K.E + (W.D)resistance...


evn i forgot my ans... but m sure they r rite... I MESSED THAT VELOCITY=3.95 PART!!! It was of 7 marks... m feeling HORRIBLE!!!
Title: Re: Mechanics Paper 42 Solutions
Post by: cockyxrocker on May 20, 2010, 11:32:20 am
for question 7(ii) didnt they ask you for the total distance travelled and not the displacement?...
i got k as zero and my expression was 225 + 3375/t
and i got 2.4 for 7(iii)
Title: Re: Mechanics Paper 42 Solutions
Post by: [Spy] on May 20, 2010, 11:49:16 am
yeah im sorry it was 36.9 :)

and yeah im sure of the rest :)

i hope i dont loose much due to silly mistakes :S
Title: Re: Mechanics Paper 42 Solutions
Post by: [Spy] on May 20, 2010, 11:59:34 am
how many marks was 5 ii) worth....how r u sure these r the ryt answers....i got all the same answers other than this part sumhow i got 0.13 as the height
dont u do 1.35-workdone against resistance=ke-pe
then PE =0.39 i think i dont remember
 


someone remind me of the particle's mass :S
Title: Re: Mechanics Paper 42 Solutions
Post by: cashem'up on May 20, 2010, 12:04:47 pm
yea i got the same answers whereas in
6 ii i got i think 3.29 because now the particle will be decelartng against friction
and for 7 ii i got k as 450
and the next part v as 5.4....yep just reassure 6 ii otherwise i m sure this is rite.....
Title: Re: Mechanics Paper 42 Solutions
Post by: [Spy] on May 20, 2010, 12:06:50 pm
yeah i did it wrong because i forgot to remove tension! GOD!! :S

but yeah k was something like that =D
Title: Re: Mechanics Paper 42 Solutions
Post by: vserian on May 20, 2010, 12:08:56 pm
hey for the 3rd question

i got the coefficient as 1.62 but coefficient of friction is not suppose to be more than 1!
i think they made an error with the qustion, i wrote 0.62 insted of 1.62

overall it was a ok paper!
Title: Re: Mechanics Paper 42 Solutions
Post by: [Spy] on May 20, 2010, 12:13:01 pm
no its not impossible to have a coefficient more than 1 but its very rare! like for all the years is always less than one and not many meterials on earth have a coefficient more than 1

but it is perfectly fine :) and its 1.62
Title: Re: Mechanics Paper 42 Solutions
Post by: cashem'up on May 20, 2010, 12:23:10 pm
no its not impossible to have a coefficient more than 1 but its very rare! like for all the years is always less than one and not many meterials on earth have a coefficient more than 1

but it is perfectly fine :) and its 1.62
yea exaclty its like on average practically it might not even be possible bt theoretically....its diferent :P
Title: Re: Mechanics Paper 42 Solutions
Post by: vserian on May 20, 2010, 01:06:32 pm
yea exaclty its like on average practically it might not even be possible bt theoretically....its diferent :P

Well every question i did about coefficients, the answer is below 1 and even theoretically its wrong
all my teaches said it shuld be under 1 and i think CIE did mistake with the paper cause if the tension in the strig is less than the weight then practically it cant move so there wont move so friction is more then the force that agaist the friction and if the cooeffficent of firction is more then 1 then friction will make objects move! thats impossible!
Title: Re: Mechanics Paper 42 Solutions
Post by: [Spy] on May 20, 2010, 01:16:06 pm
lets say there was amistake, you should have done it with the correct method F/R and whatever answer put it
not assume its wrong! even if it is, im telling you your loosing on it :)
Title: Re: Mechanics Paper 42 Solutions
Post by: Twinkle Charms on May 20, 2010, 01:20:39 pm
this paper was so freakin easy....buh i messed up in 5th (ii) part and 7th(iii) part :|
Title: Re: Mechanics Paper 42 Solutions
Post by: [Spy] on May 20, 2010, 01:23:32 pm
yeah i know yeah me too i messed in 6 part 2 and 7 part 3
Title: Re: Mechanics Paper 42 Solutions
Post by: ilmarien on May 20, 2010, 01:34:14 pm
I'm so glad I didn't study much for the exam. It was extremely easy.  :D
Title: Re: Mechanics Paper 42 Solutions
Post by: Twinkle Charms on May 20, 2010, 01:37:53 pm
I'm so glad I didn't study much for the exam. It was extremely easy.  :D
cool smarty pants =P
u take p3 n p6? if so, hows it for you?
Title: Re: Mechanics Paper 42 Solutions
Post by: cashem'up on May 20, 2010, 02:33:09 pm
hey but is neone sure of the answer in part 6ii
Title: Re: Mechanics Paper 42 Solutions
Post by: MAF on May 20, 2010, 03:18:43 pm
man, i dont yth i did this but i messed up question 4..:S
i squared the horizontal and vertical components of the vectors given before finding the resultants horizontal and vertical components....
how many marks are they gonna cut for this.....it was a mistake in one step i guess...   :-[ :-[
Title: Re: Mechanics Paper 42 Solutions
Post by: immortal on May 20, 2010, 04:18:33 pm
No use crying over split milk :P
Hope p6 & p3 goes well...
Title: Re: Mechanics Paper 42 Solutions
Post by: MAF on May 20, 2010, 05:24:38 pm
haha....i've just got AS this time....  :P
and it would have been better if you would have told me how many marks would i lose...::)
Title: Re: Mechanics Paper 42 Solutions
Post by: falafail on May 21, 2010, 06:39:54 am
   ii) -3375/t + k (though i did a silly mistake here i forgot to put K, GODDD!!! :@) so i dont know the value of K
450 :)

hey but is neone sure of the answer in part 6ii
what was the question?
Title: Re: Mechanics Paper 42 Solutions
Post by: cockyxrocker on May 21, 2010, 09:22:23 am
falafail what did u subsitute to get k ?
Title: Re: Mechanics Paper 42 Solutions
Post by: falafail on May 21, 2010, 10:21:16 am
falafail what did u subsitute to get k ?
s=225 when t=0. Then you had to add 225 for the distance covered before t=15.