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

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: [Spy] on May 20, 2010, 08:43:14 am

Title: The Exam Defied The Laws Of Mechanics.
Post by: [Spy] on May 20, 2010, 08:43:14 am
guys in mechanics paper 42, the coefficient of friction was 1.62 right?

you cant possibly get a coefficient greater than 1 :S

Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: islu_jf on May 20, 2010, 08:47:21 am
hey i got the same number 2/... i was going to change it.. bt NO TIME>!!
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: [Spy] on May 20, 2010, 08:54:05 am
no it is im 100% sure, but theoretically its wronnggg :S
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: nid404 on May 20, 2010, 09:12:10 am
no it's not....where did you read that co-eff of friction can't be greater than 1...it can very well be

Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: [Spy] on May 20, 2010, 09:17:59 am
only 2 percent of all materials on earth have a coefficient of friction greater than one! and plus, not in the book or in any paper was there a coefficient greater than one! it was pissing off, i wasted time revising the question a million times! but thank god the rest was dead easy :)
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: nid404 on May 20, 2010, 09:21:14 am
a value above 1 merely implies that the force required to slide an object along the surface is greater than the normal force of the surface on the object.

stop bothering  :P
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: islu_jf on May 20, 2010, 09:22:08 am
What did u gt for Question 5 part (ii) ??
it was about the mgh and work done against friction???
what was the hight?
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: [Spy] on May 20, 2010, 09:22:36 am
hahaha okay okay im sorry :P
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: [Spy] on May 20, 2010, 09:23:15 am
What did u gt for Question 5 part (ii) ??
it was about the mgh and work done against friction???
what was the hight?

part i) the velocity was 3

and the height was 0.32 m
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: XaM!! on May 20, 2010, 09:23:17 am
i ****ed 1 part... i couldnt prove v=3.95... because of no time...
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: nid404 on May 20, 2010, 09:24:47 am
part i) the velocity was 3

and the height was 0.32 m

yup :)
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: islu_jf on May 20, 2010, 09:33:11 am
Ohh...  i got the hight as 0.13 and then the mgh is 0.31!! which is the same as the WD against frictional force!!!!!
i ddnt do gd in the last question.. no time man..
it was Ok .. bt very long//
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: [Spy] on May 20, 2010, 09:49:26 am
:)


don't worry, you'll do good :)
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: SAKS10111 on May 20, 2010, 10:37:37 am
i also got the co-eff as 1.62, and i know its right, because it wasn't even a very complicated question. hope its right
in the 5th question, instead of taking the height as .45 m, i took it as 45 m :( my working and method is totally right, but my figures are obviously wrong, do you think i'd get some consideration marks for that? that was 7 marks, the rest of the paper i think i did pretty good.
what was your last answer, the speed/velocity? i got 5.4 i think
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: @ce/AJ on May 20, 2010, 10:38:43 am
I was getting something above 1 as well so I'm like this isn't possible and changed my answer to 0.6.
Tht's 3 marks gone!  :'(
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: neno on May 20, 2010, 10:44:17 am
Ohh...  i got the hight as 0.13 and then the mgh is 0.31!! which is the same as the WD against frictional force!!!!!
i ddnt do gd in the last question.. no time man..
it was Ok .. bt very long//
i got the same thing as u but i duno which ones ryt many ppl got 0.32 sooo im not sure which one is correct....how many marks was tht 4??
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: sloe on May 20, 2010, 11:15:18 am
Silly question, but is this CIE or EDEXCEL mechanics we're talking about?
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: XaM!! on May 20, 2010, 11:17:26 am
ya Mew cant be greater thn 1... its always less thn 1... when my mew came 1.6 i was like what the hell!!!
i checked it again n again... loast 10 mins there... :'(
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: 7ananhere on May 22, 2010, 06:33:57 pm
My coeff of friction was more than 1 too , but im sure its the right answer cause all of the working out was right
does anyone remmeber what they got for the max speed of the cutting machine??? i got 0.72
and wat was the value of A for question 7 ....i got A=4 
also i couldnt prove that B= 3375:S
Title: Re: The Exam Defied The Laws Of Mechanics.
Post by: [Spy] on May 22, 2010, 06:50:51 pm
All What You Got Is Correct :)