M1 Jan 2012 Edexcel Post-Exam discussion - Solutions and Paper in first post

OP

Original post by Parthenon93

In 8c, when weight is the only force acting on the body, should friction be working AGAINST this accelerating force?

no, friction opposes the direction of movement.

Reply 21

SirYusufXXV

Original post by Arsey

No one will know until the boundaries are released.

Apart from the last question, I thought it was very easy, so I am expecting fairly high boundaries.

Can U give some approx. figures PLEEEEASE?? Im soo anxiousss..,.

Reply 22

vishcr7

Original post by Arsey

no

we the force is removed it will continue moving up the plane, but it will be decelerating.

It will come to rest and then begin to slide back down the plane.

Once the force is removed, it doesn't immediately stop and move in the opposite direction, that is like saying when you throw a ball, the second it leaves your hand it, instead of moving away from you, it immediately moves towards you and smacks you in the face.

but from what uve calculated, u just calculated till it stops up the plane. what about the distance it traves after stopping up and then coming down?

Reply 23

SirYusufXXV

Original post by Arsey

No one will know until the boundaries are released.

Apart from the last question, I thought it was very easy, so I am expecting fairly high boundaries.

Can u give some approx. figures please? Thanx... and is there ecf??

Reply 24

vishcr7

Original post by Arsey

yep

no mark for it at all?

Reply 25

vishcr7

and also arsey, question 5c, i first found the final velocity of the object at s=30/5, and then that was my initial velocity for the length of time that i would be above 30/5 metres. used 2u/g to get a different answer, 2.32. do i get any marks for that?

Reply 26

OP

Original post by vishcr7

but from what uve calculated, u just calculated till it stops up the plane. what about the distance it traves after stopping up and then coming down?

yes, but that isn't what the question asks for....

it is travelling at a speed of 16 up the plane

the force is removed, causing it to slow down from a speed of 16 to a speed of zero (when it stops) whllst moving up the plane.

the question, wants the distance it travels between the time the force is removed until the time it comes to rest.

Also, it will not slide down the plane anyway, since Fmax is greater than the component of the weight down the plane. Once it stops, friction will hold it in place on the plane.

Reply 27

OP

Original post by vishcr7

no mark for it at all?

no, it is wrong

Reply 28

OP

Original post by vishcr7

and also arsey, question 5c, i first found the final velocity of the object at s=30/5, and then that was my initial velocity for the length of time that i would be above 30/5 metres. used 2u/g to get a different answer, 2.32. do i get any marks for that?

no, it is wrong.

Reply 29

Darkarium

9

For question 2A I considered both particles, and found T then substituted it in to find R. I then realised 2B was asking for T and just wrote a/b. at the start of my answer. Am i likely to lose marks for this?

Also personally although I found it quite easy and got all of those answers (probably minus a few marks for accuracy here or there), I did find it an incredibly long and tedious paper - it took me almost exactly 1hr 30 to finish. I'm hoping this means the grade boundaries won't be quite so high. In my opinion previous papers have been just as easy but only 7 questions.

Reply 30

t_star

Original post by Arsey

Very easy I thought

Thankss for taking your time to post this!! :smile:

Reply 31

Mathematix

2

Merked it. Only thing different is i used -11.1 not -11.06...... In last part stupidly -.- so I think I got 11.5 not 11.6 as I took away 22.2 not 21.2, will I lose only 1 mark for this?

Reply 32

Mr.cool

Original post by Arsey

Very easy I thought

for question 5(c) you used g so shouldn't anwsers as fractions be penalised. I wrote 2.71. will that still be accepeted if fractions are allowed.

Reply 33

Alpha5

2

Grade boundaries? Maybe 75- 100 ums, 69 - 90ums, 64- 80 ums (a).... What do you think?
I think there was a few tricky questions along the way, many were thrown by the moments questions, parts of the vectors one and the last one. It felt like an average paper.

(edited 12 years ago)

Reply 34

-Illmatic-

11

15 marks dropped...not good, not good at all

edit: any chance its around 58/59/60 for 80 UMS?

(edited 12 years ago)

Reply 35

Mr.cool

Original post by Alpha5

Grade boundaries? Maybe 75- 100 ums, 69 - 90ums, 64- 80 ums (a).... What do you think?

i didn't think it was that easy even though from what i have seen of aresy mark scheme i seem to have gotten all the questions correct.
There could be lots of slips ups. 5(c), 7(c) and 8(c) will provide some discrimination at the top grades. Even the bearings question i have seen examiner reports say have been poorly done recently.

Reply 36

Mr.cool